Here in Oregon almost all of the ant species and the two main termite species rely on an exact combination of atmospheric and seasonal conditions to time their mating flights. In Beaverton, Tigard, and Tualatin these flights are earlier than in Hillsboro or the West Hills of Portland. Even 500 ft. of elevation changes the frost dates and the insect activity cycles.
The ant colonies produce winged reproductives in the nests and nurture them until the time is right for their brief mating flight. In a given neighborhood or local area, all of the colonies of the same species take to the air at almost exactly the same time. This exact timing of these different nest flights is critical to a sucessful mating season.I have observed that the right conditions to include calm winds, strong sunlight to provide strong thermal updrafts, and relatively cool temps, again to help with the thermal updrafts.
In Beaverton, Tigard, and Tualatin these thermals can be generated by a dark roof or an asphalt paved cul de sac. The technicians at Nature First Pest Control often comment to me about the diferent activity levels of insects and rodents on different facing slopes that have differing amounts of sun exposure. For the termites and ants ongoing survival, timing is everything. Successful Ant Exterminators know about, and expect these natural cycles in their areas.