Relative humidity when it rains

Dear Tom,
Watching hourly weather reports, I notice the relative humidity is often not
100 percent when it is raining. Is this correct?
Simon Palmer
Dear Simon,
It's correct, and it can rain when the relative humidity is less than 100
percent. In fact, relative humidity values are in the range of 90 to 99
percent most of the time when it is raining.
Clouds form when invisible water vapor gas condenses into visible water
droplets, and rain occurs when cloud droplets grow too large to be supported
by currents of rising air within rain clouds. Condensation and raindrop
formation occur within clouds -- where the air is saturated and the relative
humidity is, indeed, 100 percent.
Most of the time, though, clouds lie above drier air at the ground, and
that's where we live. Relative humidity at the surface reflects the actual
moisture content of the air at ground level -- drier air into which rain is
falling.