Weather will likely play an important role when you plan your trip to La Union, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually July and May, with an average temperature of 27°C, while the coldest months are March and February, with an average of 25°C. The rainiest months in La Union are September, August, June and October, with each month seeing an average of 230 mm of rainfall.