Weather will likely play an important role when you plan your trip to Santa Monica, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually March and October, with an average temperature of 28°C, while the coldest months are July and June, with an average of 26°C. The rainiest months in Santa Monica are May, June, July and April, with each month seeing an average of 335 mm of rainfall.