What term refers to a prolonged period of dry weather?

The term that refers to a prolonged period of dry weather is "drought." A drought is characterized by a significant reduction in the availability of water due to an extended period of below-average precipitation. This can have serious implications for agriculture, water supply, and the environment, as it leads to crop failures, water shortages, and ecological stress.

The other terms provided have distinct meanings unrelated to prolonged dry weather. "Flood" refers to an overflow of water onto land that is normally dry, often caused by excessive rainfall or melting snow. "Heatwave" describes a prolonged period of excessively hot weather, which may or may not include dry conditions. "Monsoon" refers to a seasonal prevailing wind that brings heavy rainfall to certain regions, particularly in South Asia, and is associated with wet weather rather than dry spells. Thus, "drought" is the accurate descriptor for extended dry weather conditions.