Weather will likely play an important role when you plan your trip to Surrey, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July, with an average temperature of 17°C, while the coldest months are December and February, with an average of 4°C. The rainiest months in Surrey are November, January, December and March, with each month seeing an average of 284 mm of rainfall.