The hot weather is slowing down fruit production in the garden dramatically. My summer squash (which I planted a dozen hills) usually produces more than I certainly can use. The plants now produce maybe one fruit every few days, which is good. It is bad concerning other vine crops like cucumbers and melons. Below-ground vegetables like carrots and beets are doing well. My winter squash is setting on a lot of fruit, mainly because they are growing between shady fruit trees. Peppers have not set and the ones that have are small.
You notice it with the tomatoes, fewer are setting and not ripening. Green tomatoes are full of chlorophyll and when maturing tomatoes produce lycopene and carotene from ethylene gas breaking the chlorophyll down. This turns the fruit red or yellowish depending on the variety. When the temps are above 85 the ripening slows down and when above 95 the ripening can stop. When they do ripen, they can have tough skins. If that is not enough, you may notice the tops (collars) of the fruit will stay green because the temps are hotter at the top of the tomato preventing the top from ripening.
The best thing to do with this heat is to mulch your plants to keep the ground cooler. Also, do not be stingy on the water since the tomato is mainly water. Inconsistent watering will crack the fruit depending on the variety. Keep in mind that cooler weather is on the way.
Some say to remove the growth in between the main leaf and stem. This is good when you want to force ripening in the fall. In the summer, if you remove too much green growth, you may cause more delay in ripening and cause sunburning of the fruit.
Leaf diseases are more prevalent in hot weather especially if you overhead water. Remove any diseased leaves and try a garden fungicide.
Also, blossom end rot is a problem again depending on the variety. This is caused by inconsistent watering and hot weather tying up the calcium in the soil.