Though weather is generally mild all year, most visitors head for Napa in the cool of spring and fall. Summer can be somewhat hot, while in the winter rains can ruin the fun. Flooding is common in the winter, and roads are often closed for this, so getting around can be tricky.

The best advice is to plan the timing of your trip to what your plans are. If you plan to hike or bike in the area – common activities in this natural and scenic area – plan your trip for fall or spring, though it can rain well into May. If you don’t mind highs in the high 80s, then by all means head for Napa in the summer.  

Are you primarily planning to drive from winery to winery? Maybe add a day of shopping and spend some long hours eating? In that case, winter might suit you well. Crowds won’t be a problem and dashing from car to winery door in the rain shouldn’t create too much havoc and might even add to the fun. 

Overall, temperatures are mild in Napa. January is the coldest month, with highs usually in the mid to high 50s. July is the hottest month. While highs can reach into the 100s, the average daily high in July sits around 85.