Tropical rainforests hover around 25 to 27 °C (roughly 77 to 81 °F) year-round, making them among the most thermally stable environments on Earth. The annual swing between the warmest and coolest months is often less than 2 °C, which is smaller than the temperature change many cities experience between morning and afternoon on a single day. That apparent monotony hides real complexity, though. Temperature shifts dramatically depending on where you measure within the forest, whether the canopy is intact or stripped away, and how large-scale climate patterns like El Niño ripple through the tropics.
Why the Temperature Stays So Narrow
Tropical rainforests sit near the equator, where the sun’s angle changes little across the year. Day length barely varies from one season to the next, so the solar energy arriving at the canopy is remarkably consistent. On top of that, the dense canopy itself acts as a giant insulating blanket. Leaves absorb and scatter sunlight during the day, keeping the forest floor cooler than the air above the canopy, while at night the canopy traps warmth and slows radiative cooling. The result is a temperature regime that drifts within a few degrees over an entire year.
Moisture plays an equally important role. Tropical rainforests receive roughly 1,700 to 3,000 mm of rain per year, depending on the region. All that water cycling through vegetation drives immense evapotranspiration, essentially the forest sweating. Trees release water vapor through their leaves, and the phase change from liquid to vapor consumes heat, pulling energy out of the surrounding air. A global comparison of satellite-measured land surface temperature and weather-station air temperature found that surface temperature in tropical rainforests is actually lower than near-surface air temperature because of this strong evaporative cooling, a pattern that holds throughout the year.
Temperature From the Canopy Down to the Soil
If you could ride an elevator from the top of a tall rainforest tree down to the roots, you would feel the temperature change in ways that a single weather station number never captures. Research in a tropical seasonal rainforest showed that mean air temperature rises steadily with height from the forest floor until roughly 46 meters up (about 17 meters below the canopy surface), then levels off through the upper canopy.1iForest – Biogeosciences and Forestry. Quantifying the vertical microclimate profile within a tropical seasonal rainforest, based on both ground- and canopy-referenced approaches The daily temperature swing also behaves differently at different heights: deep inside the understory, daily ranges are compressed, while the exposed upper canopy heats and cools more freely.
Below the surface, the trend reverses. In a lowland rainforest in Sarawak, Malaysia, the daily temperature range was greatest at the soil surface and shrank rapidly with depth. By about 40 centimeters below the forest floor, daily temperature fluctuations essentially disappeared, dropping below 0.1 °C.2Bulletin of the Institute of Tropical Agriculture, Kyushu University. Characteristics of Soil Temperature and Heat Flux within a Tropical Rainforest, Lambir Hills National Park, Sarawak, Malaysia No clear seasonal pattern showed up in the soil, either. A separate study in the Brazilian Amazon found that both daily averages and daily ranges of soil temperature in the upper layer were smaller beneath forest than in nearby cleared pasture, reinforcing the idea that intact forest is a powerful thermal buffer underground.3Journal of Geophysical Research: Atmospheres. Intradiurnal and seasonal variability of soil temperature, heat flux, soil moisture content, and thermal properties under forest and pasture in Rondônia
Not All Tropical Rainforests Feel the Same
The phrase “tropical rainforest” covers a huge range of geography. A lowland forest in the Congo Basin at 400 meters elevation experiences different baseline temperatures than a cloud forest on an Andean slope at 2,500 meters or a dipterocarp forest in Borneo at sea level. As a rough guide, lowland equatorial forests cluster around 25 to 27 °C, but montane tropical forests (sometimes called cloud forests) can average 10 to 18 °C, depending on altitude. In the highest-elevation cloud forests of Colombia, conditions are cool and perpetually wet, and the characteristics of these forests are strongly shaped by soil moisture and nitrogen availability rather than temperature alone.4Cambridge University Press. Effect of water, temperature and fertilizers on soil nitrogen net transformations and tree growth in an elfin cloud forest of Colombia
Even among lowland forests, regional differences matter. An analysis of roughly 16 million satellite-derived biomass estimates across intact forests in the Amazon, the Congo Basin, and Southeast Asia found that climate’s relationship to forest biomass varies by region. Temperature is the dominant factor in drier forests, with the Congo Basin showing the greatest sensitivity to warming, while Southeast Asian forests respond more strongly to water limitation.5Nature. Heterogeneous climatic controls on tropical-forest biomass In practical terms, the same 1 °C increase in mean temperature might barely register in a well-watered Bornean forest while meaningfully stressing a seasonally dry patch of Congolese forest. The “average temperature” headline number masks these regional vulnerabilities.
How Deforestation Heats the Landscape
Remove the canopy and all of its evaporative cooling, shade, and air-mixing capacity, and local temperatures climb. A global study of forest cover change found that deforestation consistently warmed tropical regions by about 0.4 °C on average, and where roughly half the forest was lost, surface temperatures rose by about 1 °C.6PLOS ONE. Impacts of forestation and deforestation on local temperature across the globe The warming comes from changes to the surface energy budget: the bare or grassy ground reflects sunlight differently, holds less moisture, and generates different patterns of heat exchange with the atmosphere.7Environmental Research Letters. Large scale tropical deforestation drives extreme warming
The human cost of this warming is not abstract. One study estimated that warming from tropical deforestation between 2001 and 2020 was associated with roughly 28,000 additional heat-related deaths per year.8PubMed Central. Tropical deforestation is associated with considerable heat-related mortality The effect is strongest in areas where forest loss is extensive and where communities lack the resources to cope with higher temperatures. In a sense, the stable “average” temperature of the tropical rainforest is not just an ecological curiosity; it is a form of climate regulation that millions of people depend on.
El Niño and the Temperature Spikes
The year-to-year steadiness of tropical rainforest temperatures breaks down during strong El Niño events. During the 2015–2016 El Niño, land surface temperature anomalies over the Amazon broke records, peaking at about 1.5 °C warmer than the previous record during the 1997 event and roughly 2 °C warmer than the 1982–1983 El Niño.9Scientific Reports. Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015–2016 These temperature spikes come paired with drought, which reduces evaporative cooling and exposes trees to stress they are poorly equipped to handle.
Deforestation and El Niño can compound each other. Simulations of Borneo’s climate showed that forest loss caused greater warming during El Niño conditions than during neutral years. In deforested areas of southern Borneo, the temperature increase reached about 1 °C during El Niño dry seasons, compared with roughly 0.3 °C during neutral conditions.10Environmental Research Letters. Compounding impact of deforestation on Borneo’s climate during El Niño events The forest that would normally dampen the El Niño temperature spike is no longer there to do so, and the landscape heats up more than either factor alone would predict.
Looking ahead, climate models project that the effect of El Niño on temperature variability in tropical rainforest regions could become detectably different from historical norms within a few decades. For northern South America, that emergence could happen as early as the 2040s, with central Africa and Southeast Asia following in the 2050s and 2060s.11npj Climate and Atmospheric Science. Early emergence of climate change in tropical rainforest temperature variability due to ENSO In other words, the familiar El Niño rhythm that has shaped tropical forests for millennia is itself shifting.
The Long Warming Trend
Beyond any single El Niño event, the baseline temperature of tropical rainforests has been climbing. Since the mid-1970s, all major tropical rainforest regions have warmed at about 0.26 °C per decade, in step with the global rise attributed to greenhouse gas emissions.12PubMed Central. Spatial patterns and recent trends in the climate of tropical rainforest regions Before that, most tropical rainforest regions showed little net temperature trend, and the western Amazon actually cooled slightly, probably due to a natural multi-decade ocean oscillation. The post-1970s warming has been consistent enough across all three major tropical forest blocks to leave little doubt about its cause.
A quarter-degree per decade sounds modest, but it accumulates. Over the roughly five decades since the warming trend took hold, rainforest temperatures have risen by more than a degree on average. For organisms evolved in one of the most thermally stable environments on the planet, even small shifts can matter. Research on Amazonian woody plants found that their ability to adjust their heat tolerance upward as temperatures rise is generally too weak to keep pace with warming.13PubMed. Leaf thermal safety margins decline at hotter temperatures in a natural warming ‘experiment’ in the Amazon Across tropical forests in South America, Southeast Asia, and Central Africa, the gap between the temperature at which tree photosynthesis breaks down and the actual maximum canopy temperatures they experience has been narrowing over the past two decades.14PubMed Central. Tropical forests are facing increasing risks of exposure to critical temperature thresholds
Measuring Temperature in a Rainforest Is Harder Than It Sounds
One reason the “average temperature” question resists a clean single number is that measuring temperature in a tropical rainforest is surprisingly tricky. Standard weather stations sit in clearings with instruments about 1.5 meters above the ground. That setup captures ambient air temperature, but it misses the extreme variation hiding in the forest’s three-dimensional structure. A study comparing surface temperatures to ambient air readings across multiple tropical forest sites found that spatial variability in surface temperature on a single day exceeded the temporal variability in ambient temperature across an entire month.15Biotropica. Extreme thermal heterogeneity in structurally complex tropical rain forests A sun-exposed branch at the canopy top, a shaded epiphyte-covered trunk, and a waterlogged patch of leaf litter can all coexist within a few meters and differ in surface temperature by many degrees.
Satellites face the complementary problem. They see the canopy surface from above, and strong evaporative cooling means that the satellite-derived land surface temperature in tropical rainforests is often lower than the air temperature measured at a weather station nearby.16Journal of Geophysical Research: Atmospheres. Spatiotemporal variations in the difference between satellite‐observed daily maximum land surface temperature and station‐based daily maximum near‐surface air temperature This is the opposite of what happens over deserts and bare land, where satellite surface temperatures run hotter than air temperature. The discrepancy matters because many regional and global climate analyses rely on satellite data, and misinterpreting the canopy surface temperature as equivalent to the air temperature a person or animal experiences on the forest floor would distort the picture.
Afternoon Storms and the Daily Cycle
If you stood on the forest floor in the Amazon, you would feel a fairly predictable daily rhythm. Morning temperatures climb as sunlight filters through the canopy, usually peaking in the early afternoon somewhere in the range of 30 to 33 °C at the canopy level. Then, most days during the wet season, convective thunderstorms build and release a deluge between roughly noon and late afternoon. These storms cause sharp drops in temperature as cool, rain-chilled air plunges through the canopy.17Atmospheric Chemistry and Physics. Total OH reactivity over the Amazon rainforest: variability with temperature, wind, rain, altitude, time of day, season, and an overall budget closure The dense forest dampens the wind and temperature swings associated with these storms as you descend through the canopy layers; instruments placed inside the canopy at 14 and 22 meters have recorded significantly weaker disturbances than those measured at the canopy top.18Atmospheric Chemistry and Physics. Planetary boundary layer evolution over the Amazon rainforest in episodes of deep moist convection at the Amazon Tall Tower Observatory
After the rain passes, temperatures recover slowly through the late afternoon, then drop overnight to their coolest point just before dawn, typically around 22 to 24 °C in the understory. The daily range in the understory (roughly 5 to 8 °C) is modest by global standards but still larger than the annual range. That is the paradox of tropical rainforest climate: the day-to-night swing exceeds the winter-to-summer swing.
What Canopy Temperature Tells Us During Drought
Scientists studying the forest’s response to heat and water stress have started paying close attention to canopy temperature, the actual surface temperature of the uppermost leaves, rather than just air temperature. In a tropical rainforest in southwest China, the difference between canopy temperature and air temperature shifted by more than 2 °C between the wet and dry seasons.19iForest – Biogeosciences and Forestry. Canopy temperature variability in a tropical rainforest, subtropical evergreen forest, and savanna forest in Southwest China During a drought year, the canopy ran nearly 0.8 °C warmer than the air, whereas in a normal year, transpiration kept the canopy slightly cooler than the surrounding air. The explanation is straightforward: when soil moisture drops, trees close their stomata to conserve water, which shuts down transpiration and removes the cooling effect. The canopy then heats up, even if the air temperature recorded by a nearby weather station has not changed much.
This distinction between air temperature and leaf temperature is increasingly important for understanding how forests will cope with climate change. A tree does not experience “average air temperature”; it experiences the temperature of its own leaves, which can diverge from the air by a degree or more depending on water supply and sunlight exposure. As droughts become more frequent in some tropical regions, canopy temperatures could rise faster than air temperature trends alone suggest.
Ancient Tropical Forests Under Much Warmer Conditions
For perspective, the range of temperatures tropical rainforests currently occupy is relatively cool compared with what they have tolerated over geological time. A compilation of nearly 6,000 temperature estimates spanning the past 120 million years found that the tropics have been as much as 7 °C warmer than today during parts of the Cretaceous and the early Paleogene periods.20Annual Review of Earth and Planetary Sciences. Global Warming and Neotropical Rainforests: A Historical Perspective During the Paleocene-Eocene Thermal Maximum about 56 million years ago, when tropical temperatures spiked by 3 to 5 °C within a geologically brief window, pollen records from Colombia and Venezuela show that the tropical rainforest did not collapse. Instead, plant diversity and the rate of new species appearing actually increased.21PubMed. Effects of rapid global warming at the Paleocene-Eocene boundary on neotropical vegetation
That sounds reassuring, but the context is different from today’s situation. The ancient warming unfolded over thousands of years, not decades, giving species time to migrate and adapt. And the forests that survived were continuous, unbroken expanses with no roads, farms, or cities blocking species movement. Modern tropical forests face warming at a much faster pace while simultaneously being fragmented by land-use change, which limits the ability of species to shift their ranges in response to rising temperatures. The paleoclimate record shows that tropical forests are not inherently doomed by heat, but it does not guarantee survival under the combined pressures of rapid warming and habitat loss.