We're supposed to have sun here all week--more sun, less humidity and less heat. I think it's wonderful.
However, to help with your problem try Time For You, Time For Me. Tell the girls that ONLY if they behave and let you sew then they get equal or double time in the pool. Sew for 2 hours in the early morning, pool in the afternoon. Or pool for a couple of hours in the morning and sew in the afternoon heat.