Tijuana, and generally, the whole of Baja California, Mexico is considered to be one of the driest, hottest regions in the North America continent, making it the ideal place for beaches and other summer water sports. However, there is a little part of Northwestern Mexico surrounding Tijuana that possesses a more Mediterranean climate with some bits of coastal fog, with a winter rainy season very much similar to that of Southern California.
In Tijuana, the rainy season begins at around November and lasts throughout December, January, February, before dwindling down when March rolls in. This is perhaps to counterbalance the fact that the rest of the year has little to no precipitation. These winter storms produce as much as 12 inches of rainfall each year for the coastal and mountain regions surrounding the Tijuana region. This amount is considered enough, for the rainforests and other vegetation to survive the rest of the years, especially those in elevated regions. Some of these winter storms are generated from as far as the Gulf of Alaska.
As for the regular weather, daytime in Tijuana Mexico is generally warm and dry, save the days during the rainy months, while virtually all evenings are cool and a bit chilly, regardless of how hot it was during the day.
The hottest months are from July to September, where temperatures may reach up to 85o Fahrenheit, especially during August. The coldest months are during the rainy season, from December to February, with temperatures dropping as low as 44o.