During the hot, humid summer months, meteorologists often discuss the heat index instead of the actual air temperature. But how is the heat index calculated, and why is it more important than the air ...

Grandma may have been right about keeping a teakettle warming on the stove in winter to moisten the air. Studies of seasonal influenza have long found indications that flu spreads better in dry air.

Across much of the world, hotter days are no longer arriving alone. The air itself is changing, sometimes turning from dry ...

Some hot days feel even worse thanks to high humidity, trapped heat and dew points. Cities are especially vulnerable. By Nazaneen Ghaffar Nazaneen Ghaffar is a reporter on The Times’s weather team. It ...