["Review of Development Economics, EarlyView. ", "\nABSTRACT\nThis paper examines how extreme heat affects fertility behavior among rural households in China. Using nationally representative survey data from the 2010–2015 waves of the CGSS, we show that greater exposure to harmful degree days (HDD) during the growing season significantly reduces households' fertility intentions—measured by the ideal number of children—and also lowers actual fertility. The evidence suggests that extreme heat depresses agricultural income and raises child‐rearing costs, consistent with a quantity–quality trade‐off. We further find that extreme heat weakens son preference. Importantly, adaptation measures such as agricultural insurance and crop diversification help buffer these adverse effects. These findings highlight the need for climate‐adaptation policies to mitigate the impact of extreme heat on demographic behavior in developing regions.\n"]