A century of reforestation in the Eastern United States (EUS) has contributed to cooling the land surface and near-surface air temperature, explaining the anomalous lack of 20th-century warming in the region. The study, using cross-scale approaches and multiple data sources, found that EUS forests cool the land surface by 1–2°C annually compared to nearby grasslands and croplands, with the strongest cooling effect during midday in the growing season. Young forests (20–40 years) have the most significant cooling effect on surface temperature, and this cooling extends to near-surface air temperatures, reducing midday air temperature by up to 1°C. Historical land cover and temperature trend analyses showed that reforestation areas were up to 1°C cooler than neighboring non-reforested areas, and areas dominated by regrowing forests were associated with cooling temperature trends. This indicates that reforestation contributed to the slow pace of warming in the EUS, highlighting its potential as a local climate adaptation strategy in temperate regions.A century of reforestation in the Eastern United States (EUS) has contributed to cooling the land surface and near-surface air temperature, explaining the anomalous lack of 20th-century warming in the region. The study, using cross-scale approaches and multiple data sources, found that EUS forests cool the land surface by 1–2°C annually compared to nearby grasslands and croplands, with the strongest cooling effect during midday in the growing season. Young forests (20–40 years) have the most significant cooling effect on surface temperature, and this cooling extends to near-surface air temperatures, reducing midday air temperature by up to 1°C. Historical land cover and temperature trend analyses showed that reforestation areas were up to 1°C cooler than neighboring non-reforested areas, and areas dominated by regrowing forests were associated with cooling temperature trends. This indicates that reforestation contributed to the slow pace of warming in the EUS, highlighting its potential as a local climate adaptation strategy in temperate regions.