July is the hottest month in Grantham with an average temperature of 21°C (70°F) and the coldest is January at 1°C (34°F) with the most daily sunshine hours at 10 in August. The wettest month is June with an average of 90mm of rain. The best month to swim in the sea is in August when the average sea temperature is 16°C (61°F).
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Sunrise 07:23
Sunset 16:10
Sunrise 07:23
Sunset 16:10