Nah, taint nowt to do with being frightened of an impending downpour. Usually see flying ants, once the warmer air is around, generating thermals for them to take to the air and spread over far distances. However, the conditions usually have to be right, typically around 25C, and with not much air movement, purely reliant upon the thermals and not wind to depart, as it's easier to take off in those conditions. It's interesting as here they have been preparing for the last 3-4 days, but as it was so windy they stayed close to the ant domains. Today the wind fell away, the heat wacked nicely to around 25C and orf they jolly well went.