I shoot a 100yd rimfire league in the summer. Anshutz target rifles,20+ power target scopes,stupid $12 a box target ammo. You need to shoot within 1" groops to be in the running with the big boys.I am not quite giving them a run (the top shooters) but I am trying. The rimfire bullet is fairly slow (1100fps) and a small puff of wind will drift the bullet 1/2" or better.
One day we set up the targets and got prone on our mats under the roof at the fireing line just as the sky opened up and was raining cats and dogs. You would think in a 40 round match you would catch a raindrop with some bullets but it just didn't happen. Four of us had got set up,warmed our barrels and taken our sighter shots by the time the rain started so we shot the match and all our scores were very close to the averages we had been running that season .
Seems to go against logic ,I guess that there is a shock wave moveing ahead of the bullet slideing the drops out of the way.
For whatever reason raindrops don't seem to upset slow rimfire. Faster or faster spinning bullets might be a different story .