How do you girls handle taking your babies in strollers out in the rain? Do you just use a rain cover over the car seat and let the rest of the stroller get wet?

I'm supposed to go to a birthday brunch soon and its raining pretty good out. The party is about 30 miles away and I'm inclined to not go at all now, but I hate flaking. My baby is almost 5 months but I haven't taken her out in the rain. Its supposed to be the most rain my area has gotten in a long time, so more than just a drizzle.