Was I upset that it rained on our wedding day? Yes, because we only got a few photos outdoors and couldn't have cocktail hour outside. But one of the best shots our photographers got were the two of us walking back into the schul as it stared drizzling while Dave held a lavender umbrella over us - and his brother, the best man, held my train.
After seeing the forecast my mom and I ran to a dollar store and found colored umbrellas and the lavender ones matched the weddings color palette so it worked out great in photos. But it would have been a great photo even if the umbrella was black or had a pattern.
If rain is in your wedding day forecast grab a few umbrellas and hope for the best. There's nothing you can do about the weather so don't stress about it. And if your wedding will be entirely outdoors, make sure you reserve a tent and the necessary accoutrements just in case you need them.