I like to do my (two pot) paint jobs in early spring when the temperatures are still low. As an amateur painter I don’t have the skill to paint fast and a temperature around 14C allows me much more time before the paint gets to tacky to handle. I have not seen any ill effects so far while painting at these lower temperatures. Painting in the early spring also has less insects and dust to disturb my work. Try, if posible, to paint on day with little wind and just after a shower to minimise dust.
If you do get some dust or insects in your work, do nothing. If you try to take a fly from wet paint you will damage your work much more then leaving it sit. Once the paint has set you can simply wipe of the fly. Most often only its legs have touched the paint (flies don’t want to die in a puddle of paint) leaving almost invisible marks. Those marks if visible, and other dust marks after wiping off, are often easy removed with some car polish, but only try polish after the paint has thoroughly set.