One of the ways that we know that hot season is upon us - other than feeling stifled by the heat all the time - is that the Dok Khun tree starts to bloom. Tuk-tuk drivers tie them to their vehicles for color and good luck. They are also used in blessing ceremonies for the Lao New Year (13 - 15 April), where the flower is dipped in water blessed by a Buddhist monk and then sprinkled on people attending the ceremony. The monk also splashes water on the building and on vehicles that people would like to bless.
The common English name is Golden Shower Tree.