We hit a spell of cool weather the past few days. Whenever you get this kind of weather during a hot spell, go out and lightly shake your tomato, pepper and eggplants for about 10 seconds each. Tomatoes in particular have trouble setting fruit when temperatures are above 95F.
They set during the cooler weather of spring and then stop setting when it is hot. When we get this cool weather they may go ahead and set if they get visits from bees or if the flowers are disturbed. Shaking the plant releases the pollen that bees normally help release by their invasive visits to the flowers.
Even if you have no bees around, shaking the plants may be enough to help them set fruit while it is cool. They will stop again when it gets hot but you may get a few to set now if they are disturbed.