Relative humidity measures how much moisture is in the air compared to how much it could hold at a given temperature. It is simply the dew point temperature divided by the air temperature, times 100.

NORFOLK, Va. — Most summer days, you hear us talk about “humidity” when describing how the air feels. While many people are familiar with the term relative humidity — the percentage of water vapor in ...

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 ...

The first major heat wave of summer has enveloped much of the midwestern and eastern U.S. in a brutal “dome” of record temperatures and high humidity. The dome phenomenon happens when weather ...

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