Don’t check the weather.
Order a clear plastic umbrella a few months ahead of time just to be safe ($14, amazon.com), then stop looking at your weather app. People will text you and call you to tell you they checked the weather. Ignore them. There is zero point in stressing about things that exist outside the realm of your control. Think about something else. Besides, overcast skies are better for photos anyway. Mother Nature is like a dragon: She will do whatever she wants, even on your wedding day.