Rain is bad, weather it's warm or cold, it can be bad. If they are 12-24 hours old before the rain comes then they are much stronger and usually a short heavy rain won't kill them. But if they are born in the rain and have no way to dry off, it can be very bad. I lost a set of twin does born in the middle of the night during a 65 degree rain.One was dead by morning, the other was weakened and didn't make it a week, that being said I also had several sets born in heavy rain and all survived. You just never know really All you can hope is your does are smart enough to have them in a shelter. That gives the fawns the best chance