Other facts from our historical weather data: Which is the warmest month in Selsey? August has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Selsey? The coldest month is February with an average maximum temperature of 9°C (48°F). Which is the wettest month in Selsey? November tops the wettest month list with 117mm (4.6 in) of rainfall. Which is the driest month in Selsey? May is the driest month with 55mm (2.2 in) of precipitation. No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.