I've flown in light rain. I flew my very familiar Four Star. It started stalling at a higher speed on final. I didn't know why till I picked it up. It had gained noticeable weight from the water droplets on the monokote. The airfoil could have been compromised due to the droplets too. My experience was lower visibility, higher stall speed and the bottom of wing was muddy :-P I need some mud flaps I guess.

Peace,
J