Forests exhibit regionally varying effects on JJA cloud cover based on MODIS **data** (overpass at 13:30 local time, Fig. 1a). Most temperate and boreal forests in Eurasia and North America have higher cloud fractions than non-forest, indicating a cloud enhancement effect (positive ΔCloud) accounting for 63.21% of all grid samples with a global mean magnitude of +0.0133. In contrast, forests in South Amazon, Central Africa, and Southeast US have lower cloud fractions than nearby non-forest, signifying a cloud inhibition effect (negative ΔCloud) over the forest with a global mean magnitude of −0.0115. The strength of these contrasting cloud effects (i.e., cloud enhancement and inhibition) follows a latitudinal dependency with the largest magnitude in the tropical regions and diminished toward higher latitudes (Fig. 1b). This is likely due to preferential conditions for convection development at low latitudes, as indicated by their high convective available potential energy, which decreases at higher latitudes 27 . Our additional sensitivity tests indicate that the global pattern of ΔCloud holds when estimated using alternative window sizes ( Supplementary Fig. 2) and split time periods (2002-2007, 2008-2013, 2014-2018, Supplementary Fig. 3), suggesting the robustness of results to scale of a local window and interannual variability of cloud cover.