The weather in Modesto in September is hot. The average temperatures are between 17°C and 35°C. Usually the days in September are hot while the nights are a bit cooler.
There shouldn't be any rainy days in in Modesto during September. Having said that, the days are very hot in September so hanging out outside is more recomanded during the after noons and evening time.
Our weather forecast can give you a great sense of what weather to expect in Modesto in September 2025.
If you’re planning to visit Modesto in the near future, we highly recommend that you review the 14 day weather forecast for Modesto before you arrive.