The temperatures in Grantham in September are usually low and can range between 11°C and 18°C.
You can expect about 3 to 8 days of rain in Grantham during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Grantham in September 2025.
If you’re planning to visit Grantham in the near future, we highly recommend that you review the 14 day weather forecast for Grantham before you arrive.
Temperatures
18° / 11°
Rainy Days
3
Snowy Days
0
Dry Days
27
Rainfall
40
mm
Sun Hours
4.4
Hrs
