I think the best way to make adjustments depending on the weather is to expect and prepare for the worst. Be prepared in case it rains. I know a lot of people who are very good at running even on hot or cold weather. Load up on anti oxidants to avoid getting sick the next day. It's not always about the weather. Sometimes it's not even how much you take care of yourself. If you are happy, nothing can wear you down. Even on a gloomy day, you're mood is still sunny and it's going to be contagious.