When it's just too hot to cook, you can still put up a tomato relish using this recipe.

8 lbs. ripe tomatoes, blanched, peeled, and chopped (about 25-30 tomatoes)
3 medium onions, chopped
1 small red hot pepper, chopped
6 cups brown sugar
2 tbsp. mustard seed
1/2 tbsp. celery seed
1/2 cup salt
2-1/2 cups vinegar

Combine the chopped vegetables in a big bowl, sprinkle them with the 1/2 cup salt, and stir. Let the mixture stand for 2 hours. Then pour it into a jelly bag and let it drain overnight or until the mixture is entirely dry. When the vegetables have drained dry, mix the sugar, vinegar, and spices in a pot and heat them until dissolved, stirring occasionally. Pour this liquid over the drained vegetables, stir, and ladle the relish into hot, sterilized pint jars. Cover and process in a boiling bath for 15 minutes.
*We suggest pressure canning tomato relishes at 10 pounds pressure for 10 minutes.