Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →California coast redwoods can survive dry summers and short heat events, but drought and extreme heat put pressure on the trees in different, interacting ways. Drought reduces the water available for transpiration and cooling; heat can raise leaf temperatures far above the surrounding air and suppress photosynthesis even when a leaf has water and its stomata remain open.
The result is measurable physiological stress, slower carbon gain, and greater risk to seedlings and regeneration. It is not possible to name a temperature at which every redwood dies: the upper thresholds for redwood photosynthesis and mortality remain unknown, and conditions vary among groves, elevations, life stages and years.
As an Amazon Associate I earn from qualifying purchases.
How drought changes a redwood’s water balance
Stomata close to conserve water
Redwood leaves exchange carbon dioxide and water vapor through microscopic pores called stomata. When soil moisture falls, the tree can partially close those pores. That response slows water loss, but it also restricts carbon dioxide entry, so photosynthesis and growth can decline.
Free tools Windows power users keep installed
One-click scans. No signup required.
Closing stomata also reduces transpiration. Transpiration is a major way a leaf sheds heat: water moving from the leaf to the air carries energy away. A drought-stressed redwood therefore loses part of its evaporative-cooling capacity at the same time that the atmosphere may be unusually hot and dry. The tree is not simply “running out of water”; it is balancing water conservation against cooling and carbon uptake.
#1 Best Overall
- [Ultra-Lightweight Ear Buds Designed for Small Ears] Each earbud weighs only 3.7g and features a compact, ergonomic in-ear design made especially for small ears. Secure, low-profile, and comfortable for workouts, all-day wear or overnight sleeping.The ultra-slim profile sits flush in your ear with no hard edges poking or rubbing, so you can even sleep on your side without discomfort.
- [Immersive Stereo Sound with TOZO OrigX Technology] TOZO OrigX tuning delivers clear vocals, balanced mids, and natural stereo sound for music, podcasts, and videos.
- [Long Battery Life for Daily Use] Get up to 7 hours of playtime on a single charge, with up to 32 hours total using the charging case—ideal for workdays, commuting, and extended listening sessions.
- [Bluetooth 5.3 & Stable Connection] Bluetooth 5.3 provides fast pairing, stable wireless performance, and reduced dropouts as you move around home or office.
- [Deep Bass with Clear Vocals] High-performance drivers produce punchy bass while keeping vocals clean and detailed for everyday listening.
Water stress can appear before visible damage
A tree may continue to look green while stomatal regulation, sap flow and photosynthesis have already changed. This is especially important for large, established redwoods, whose crowns can contain leaves at different heights and exposures. A shaded, fog-wetted branch and a sun-exposed upper crown do not experience the same combination of leaf temperature and water demand.
The University of California Agriculture and Natural Resources describes coast redwoods as not drought-tolerant and warns that longer, more extreme dry periods can stress them. That characterization describes vulnerability at the ecosystem level; it does not mean every drought kills mature trees or that all groves respond identically.
Extreme heat adds a direct photosynthesis problem
Leaves can be much hotter than the air
Measurements summarized by the University of California, Davis, followed a Mendocino County redwood forest over three summers. During summers that included temperatures above 86°F, some leaves were nearly 20°F warmer than the surrounding air. The observation matters because weather-station air temperature is not the same as the temperature experienced by a sunlit leaf.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsA leaf absorbs radiation and normally offsets some of that heating through transpiration. If water is scarce or stomata close, cooling becomes less effective. UC Davis described the finding as consistent with leaves being unable to cool themselves effectively and possibly restricting stomatal opening to conserve water.
Heat reduced photosynthesis even when water was available
The same account described laboratory tests at temperatures up to 110°F. Photosynthesis declined in leaf samples even when water was available and stomata remained open. That result separates a direct heat effect from the secondary effect of drought-driven stomatal closure: heat itself can impair the photosynthetic machinery under the tested conditions.
Rank #2
- 【IP68 Waterproof Multifunctinal Smart Watch】Torjalph fitness activity tracker smart watch is IP68 waterproof technology ,you can wear it when swimming,handwashing,it's rain-proof which means that you perform multiple exercise modes outside without worrying about sweat or rain corroding your fitness smart watch,and this watch equipped with a 230 mAh large capacity battery magnetic charging ,and this sports activity tracker watch can be used 5-7 days If fully charged.
- 【Larger 1.83'' Full Screen Watch & Multi-dial Selection】1.83 inch full HD color touch screen smart watch for men / women provides excellent 240*284 resolution image quality ,This Bluetooth smart watch offers a better touch experience and remarkable immersion and ,more than 200 watch faces for you to choose from App"Da Fit ", you can change the dial style according to your mood to wear keeping the world on your wrist
- 【Accurate Activity Tracker Smart Watch 】sports watch activity tracker uses sweat and dust resistant breathable silicone strap, our Fitness Tracker Smart Watch for Android iOS Phones supports 12 sports modes,walking,running,bicycle,swimming,badminton,basketball,football,rope skipping. This bluetooth calls smart watch for men women is lightweight and stylish, bringing more convenient and relaxing sports experience while also providing more protection.
- 【Your 24 Hour Personal Daily Health Monitor】Fitness watch for women men full touch screen IP67 waterproof bluetooth smartwatch for Android iOS Phones with heart rate blood pressure monitor multifunction Andriod smart watch with steps counter sleep monitor sports fitness watch, monitoring blood oxygen saturation allows you to understand your physical condition in real time to track fitness progress ,to know your health status in time.
- 【More Functions Bluetooth Call Smart Watch】This fitness activity smart watch full screen for iPhone and Android phones includes a bunch of new features including:The bluetooth smart watch can hang up the phone, receive and display WhatsAPP /Text /Facebook /Twitter /Messenger reminder.Support sedentary reminder, alarm clock, stopwatch, timer,weather information,music control, remote camera control compatible with Android 5.0 and above or iOS 9.0 and above smartphones.
Lily Klinek, the study’s lead author and a Ph.D. candidate in the UC Davis Plant Optics Lab when the report was issued, said, “With this work, we see there’s a significant impact of heat on photosynthesis and physiology.” She also cautioned, “We don’t know what the upper temperature thresholds are for redwood photosynthesis and mortality.” The laboratory maximum of 110°F is a test condition, not a forest-wide mortality threshold.
Why drought and heat reinforce each other
Drought and heat create two pathways to stress:
- Water-limitation pathway: dry soil or limited water supply encourages stomatal closure, reducing transpiration and evaporative cooling.
- Temperature pathway: high leaf temperatures can reduce photosynthesis even with water in the tissue and stomata open, as the laboratory tests indicated.
When both occur, a redwood may be less able to cool a leaf and may also suffer heat-related impairment of photosynthesis. That interaction is why “drought stress” alone is an incomplete explanation for what happens during a hot, dry spell. Conversely, a hot day does not prove that drought caused every physiological response; the UC Davis tests demonstrate a heat effect under adequately watered conditions.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Fog is part of the dry-season environment
Fog can wet foliage and ease atmospheric demand
Summer fog is a defining feature of the coast redwood climate. It can wet leaves directly, raise local humidity and reduce the drying power of the air. Those effects can matter during the otherwise dry season, when rainfall is limited. Fog should be understood as part of a grove’s water-and-temperature context, not as a guaranteed replacement for rain or soil moisture.
Caspar Creek measurements show strong topographic variation
A 2025 U.S. Forest Service study monitored fog, climate, soil moisture, sap flow and streamflow at the Caspar Creek Experimental Watersheds in northwestern California. Observations covered the 2020, 2021 and 2022 fog seasons, with each season defined as May 1 through September 30. The study compared hillslope shoulder and ridge positions in harvested and unharvested third-growth forest.
Fog-related leaf wetness was higher on the hillslope shoulder than at the ridge. Fog events generally produced small increases in soil moisture or reduced the rate at which soil moisture was withdrawn, although the size and direction of the response varied through the season. All monitored sites showed lower transpiration during fog periods.
Rank #3
- [Low Noise High Fidelity] New bee guitar cord with 22AWG oxygen-free-copper center conductors provides enhanced signal transfer, the PVC insulation material and the high-density stranded copper double shield provide noise rejection for quiet operation
- [Ideal for Choice] New bee 1/4 straight and right angle metal connectors, ensures a secure connection in any instrument, pedal, or amp jack. L shape great fro on stage guitar stands
- [Wide Compatible] Suitable for mixer, power amplifier, microphone, effector, decoder, equalizer, electoronic organ, electric guitar, electric bass and other electronic equipments. Widely used in the installation of smart home, karaoke speaker, professional stage audio, etc
- [Easy Disassemble] Making incidental repairs quick and easy! Very nice, flexible cable
- [Dont Hesite to Order] 24 hours customer services and professional technology team are standing by
The authors concluded that fog’s ecological and hydrological effects at Caspar Creek were influenced by topography and were not apparently controlled by forest density. That finding does not establish that every redwood grove receives the same fog benefit, nor does it show that thinning universally removes or preserves fog. A ridge, shoulder and valley can have different fog exposure even within one forest.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallWhat happens to growth and regeneration
Seedlings face a different risk profile from mature trees
Young trees have smaller root systems, less stored carbon and a canopy closer to the hot, dry boundary layer near the ground. Their survival and height growth can therefore respond differently from those of established redwoods. Reduced photosynthesis during repeated stress means less carbon is available for new leaves, stems and roots, while a seedling may allocate more of its limited carbon below ground.
What the seedling comparison found
A U.S. Forest Service report examined coast redwood and Douglas-fir seedlings during the 2015 growing season after a 2014 variable-density retention harvest at the L.W. Schatz Demonstration Tree Farm in Maple Creek, California. The site was outside the coast redwood’s natural range, and the experiment lasted one growing season.
Redwood seedlings had significantly lower water stress and lower aboveground growth than Douglas-fir seedlings. The authors suggested that stronger stomatal regulation could conserve water while reducing carbon uptake and aboveground growth; they also discussed possible allocation of carbon below ground.
Among the heavy-thinning, moderate-thinning and unthinned treatments, seedlings of both species in the heavily thinned treatment had the least water stress and the highest growth. Because this was a single-site seedling study outside the natural range, it cannot be turned into a blanket prescription to thin every mature redwood stand. Treatment changes light, wind, humidity, soil moisture and competition simultaneously, so its effects depend on site and objective.
Recommended Free Tools
Rank #4
- Digital Family Calendar: BSIMB digital calendar wall touch screen puts an end to your chaotic life. Designed for busy families, the digital calendar keeps you organised and in step with your family. Assign different colours and tasks to each family member to make family scheduling easier and more intuitive.
- Easy Setup and Auto-Sync: Plug in, connect to WLAN and auto-syn your electric calendar in minutes. Digital wall calendar compatible with Google calendar, iCloud calendar, Outlook calendar, Cozi calendar and Yahoo calendar. Add events directly on the device or through the ecalendar app. Electronic calendar stays current whether you're at work or traveling—no manual updates needed.
- All-In-One Home Assistant: Smart calendar builds habits and encourage independence with personalised chores. Display daily meal plan to reduce the daily ‘What's for dinner?’ stress. To-do lists keep track of everything you want. Turning chores into valuable achievements with stars and rewards, making life easier and more enjoyable.
- Manage Anytime Anywhere: BSIMB electronic calendar for family stay connected with the powerful ecalendar app. Access and manage your digital wall calendar anytime, anywhere with free features like stars & rewards, photo screensaver, chore charts, meals plans, to-do lists etc. Electronic planner paid features like Magic Import tailor advanced tools for users with special needs.
- Stay in Touch with Loved Ones: Share photos or videos from your phone to electronic wall calendar with app, instantly update your life moment, and keep in touch with your family, especially those who are far away; you can also surprise your smart calendar digital wall by sending him a wish card; it's also great for keeping tech-illiterate elders in touch with the youngsters.
Why regeneration is a concern at range edges
A UCANR healthy-forest brief warns that longer, more extreme dry periods and expected reductions in coastal fog could stress moisture and temperature conditions, reduce seedling regeneration and growth, and constrain forests particularly near the southern and eastern edges of the redwood range. These are ecosystem-level risk statements, not a forecast for a particular property.
The USDA California Climate Hub likewise emphasizes that forest types have distinct climate stressors and management needs, including coastal redwood. The implication is to evaluate local exposure, water conditions and life stage rather than apply one statewide rule.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Can redwoods survive extreme heat?
Often, yes. Coast redwoods evolved in a cool, fog-influenced coastal climate and can endure periods that are hotter or drier than their usual summer conditions. Survival through an event, however, is not the same as maintaining normal photosynthesis or growth. A tree can experience reduced carbon gain, depleted water reserves or failed regeneration without immediate whole-tree death.
The available heat study does not identify an upper temperature at which redwood photosynthesis stops permanently, nor a temperature that causes mortality in all trees. Its field observations document leaves nearly 20°F above air during periods above 86°F, while its laboratory tests document reduced photosynthesis up to 110°F under specified conditions. Neither number should be presented as a universal threshold.
Duration, recurrence, humidity, soil moisture, canopy position and prior stress all matter. A brief hot pulse followed by fog or cooler weather is not physiologically equivalent to repeated heat during a prolonged drought. The evidence supports concern about cumulative stress, not a single temperature-based prediction of death.
Which settings are more exposed?
No available study provides a complete ranking of California groves. The following framework organizes the documented risk factors without claiming that one category always outranks another.
| Risk axis | What the studies document | How to interpret it |
|---|---|---|
| Heat exposure and leaf temperature | Mendocino field leaves were nearly 20°F warmer than air during summers with temperatures above 86°F. | Sun exposure and limited cooling can make leaf conditions more severe than air-temperature records suggest. |
| Water availability | Drought can prompt stomatal closure; laboratory heat effects occurred even when water was available. | Assess drought and heat as separate but interacting stresses. |
| Fog and topographic position | At Caspar Creek, shoulder sites had more fog-related leaf wetness than ridges, and soil-moisture responses varied. | Fog benefits are local and topography-dependent, not uniform across a grove. |
| Life stage | The Forest Service seedling study found differences in water stress and growth between species and treatments. | Seedling establishment and mature-tree physiology should not be treated as interchangeable. |
| Geographic position | UCANR identifies southern and eastern range edges as especially susceptible to changing moisture and fog conditions. | Edge populations may have less climatic buffer, but the sources do not assign a universal risk score. |
How scientists detect stress before mortality
Physiological stress is measurable even when a forest still appears healthy. The Caspar Creek study paired several indicators rather than relying on one observation:
- Leaf wetness and fog frequency: show whether foliage is receiving local fog exposure.
- Soil moisture: reveals whether fog coincides with small moisture gains or merely slows withdrawal.
- Sap flow and transpiration: indicate how much water is moving through trees and how that flow changes during fog or heat.
- Streamflow: provides a watershed-scale context for available water.
- Leaf and air temperatures: identify whether foliage is substantially hotter than weather-station readings.
- Growth and regeneration: show longer-term consequences in seedlings and new shoots.
Using several measurements matters because a single green canopy, a single hot afternoon or a single fog event cannot represent the whole water balance of a forest. Repeated observations across ridge, shoulder and valley positions are more informative than assuming that one nearby weather station describes every crown.
What is established—and what remains unknown
Established findings
- Redwood leaves can become much warmer than surrounding air during hot conditions.
- Photosynthesis can decline under heat even when tested leaves have water and open stomata.
- Drought-related stomatal regulation can conserve water while limiting carbon uptake and cooling.
- Fog effects on leaf wetness, soil moisture and transpiration vary with topography.
- Seedling water stress and growth responses can differ from those of another conifer and from expectations for mature trees.
Questions that remain open
- The upper temperature thresholds for redwood photosynthesis and mortality have not been established.
- The cited studies do not provide a statewide statistic for heat-caused redwood mortality.
- Results from Mendocino County, Caspar Creek or a seedling site outside the natural range cannot be assumed to describe every grove.
- Fog reduction, drought severity and heat exposure will not change in exactly the same way at every latitude, elevation or topographic position.
The defensible conclusion is therefore precise: drought and extreme heat can substantially alter redwood physiology, and their combination can threaten growth and regeneration, especially where fog and soil moisture provide less seasonal relief. The evidence does not support assigning a single fatal temperature to California’s redwoods.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
