The variability of microclimate in the Amazon Rainforest

• A network of 145 sensors recorded nearly four million temperature readings (2016–2023), offering unprecedented insights into Amazonian microclimate variability. • Microclimate buffering capacity against macroclimatic temperatures is 8.6 % greater during the rainy season, highlighting the role of precipitation in thermal regulation. • Canopy height and foliage density enhance microclimate buffering, while terrain slope and solar radiation negatively impact it. • Findings highlight the importance of maintaining forest structural integrity to preserve stable microclimatic conditions essential for biodiversity conservation. The Amazon rainforest represents one of the most biodiverse places on Earth. However, the temperature experienced by organisms inside Amazonian forests, and the biophysical factors regulating microclimate, remain understudied. Microclimate patterns influence the nuances of ecological processes such as nutrient cycling, species dynamics, and tree regeneration, which cannot be captured by coarse resolution free-air temperature datasets. This study presents an unprecedented effort to measure microclimate across different biogeographical sites using standardized in-situ data collection and methodology. We analyzed temperature data from 145 sensors across eight distinct areas within the Amazon basin. From 2016 to 2023, nearly four million temperature readings revealed that Amazonian understory temperatures remained consistently lower than those of the surrounding macroclimate. The central Amazon exhibited the greatest difference between microclimate and macroclimate temperatures. All monitored sites exhibit higher buffering capacity against macroclimate during the rainy season than in the dry season. Higher precipitation, Leaf Area Index, and canopy height enhance microclimatic buffering capacity, while increased terrain slope exert negative effects. Our study provides new insights into the spatial and temporal patterns of microclimate across the Amazon basin, thus advancing our understanding of the impacts of climate change on the Amazonian Forest ecosystem.