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.

More extremely warm conditions for mid-February are in store for Chicagoland on Wednesday, with high temperatures soaring into the mid-60s in some locations.

Add Yahoo as a preferred source to see more of our stories on Google. Naser Daher, of Durham’s Old Farm neighborhood, carries his belongings through floodwaters near the Eno River in Durham on Monday ...