Heat and other climate impacts like floods and storms affect voters, candidates and poll workers in different ways at different times, and can even tip election results, researchers and officials report.

As she canvassed for Zohran Mamdani in New York City on Tuesday last week, Batul Hassan should have been elated. Her mayoral candidate—a 33-year-old state assemblymember—was surging in the polls and would within hours soundly defeat Andrew Cuomo on first preference votes in the Democratic primary election.

The July 2024 general election saw a major shift in the UK’s approach to tackling climate change. The incoming Labour government made ambitious pledges to cut emissions and switch to green energy, with a target of “clean power” by 2030 and support for on and offshore wind.