The hot season broken by moisture

Mid-May dawn: with the coming of rainy and cloudy weather, the back of the hot season seems to be broken, with dawn temperatures below 30 degC (86F) in my downtown neighborhood. At the peak of the hot weather a couple of weeks back they were consistently over 30. 

Notice the 28-30 temps downtown and the 27 or so further out including the Don Muang airport area where our long-term records are. This agrees with my previous study indicating a 2-3 deg "heat island effect" in the Sukhumvit area.