Wet-bulb temperature measures the limit of evaporative cooling, not just how hot and humid it feels. Here is why the number matters more than the thermometer reading.

Evapotranspiration — corn's version of sweating — is quietly making already brutal Midwest heat waves feel worse, and meteorologists say the effect is only ramping up for the season.

Three humidity-adjusted heat numbers dominate the summer forecast, and they answer different questions. The one everybody quotes assumes you are standing in the shade.