A drought is a period of drier-than-normal conditions. A drought can last for days, months or years. Drought often has large impacts on the ecosystems and agriculture of affected regions, and causes harm to the local economy. Annual dry seasons in the tropics significantly increase the chances of a drought developing, with subsequent increased wildfire risks. Heat waves can significantly worsen drought conditions by increasing evapotranspiration. This dries out forests and other vegetation, and increases the amount of fuel for wildfires.

മാസങ്ങളോളമോ വർഷങ്ങളോളമോ ഉപരിതല ജലത്തിനോ ഭൂഗർഭജലത്തിനോ ഒരു പ്രദേശത്ത് അനുഭവപ്പെടുന്ന കുറവാണ് വരൾച്ച.