The weather in Fullerton in September is hot. The average temperatures are between 20°C and 30°C.
There shouldn't be any rainy days in in Fullerton 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 Fullerton in September 2025.
If you’re planning to visit Fullerton in the near future, we highly recommend that you review the 14 day weather forecast for Fullerton before you arrive.
Temperatures
30° / 20°
Rainy Days
0
Snowy Days
0
Dry Days
30
Rainfall
4
mm
Sun Hours
11.4
Hrs
