How hot is very hot? Tomatoes like warm weather but they don't like really hot. They have trouble setting fruit much over 90 degrees... but still usually you would see blossoms, they would just drop off instead of becoming tomatoes. And if your night time temperatures are staying really high, then you are probably right to bring it in:
Temperature and Humidity. Daytime temperatures above 90Ã‚Â°F and night temperatures above 70Ã‚Â°F result in reduced flowering and fruit set. There is considerable evidence that night temperature is the critical factor in setting tomato fruit, the optimal range being 59Ã‚Â° to 68Ã‚Â°F. With night temperatures much below or above this critical range, fruiting is reduced or absent. Low temperatures reduce the production and viability of pollen. High temperature, especially if accompanied by low humidity and moisture, hinders fruit set through failure in pollination and/or fertilization.
But reduced is operative in here. I've certainly had tomatoes that were fruiting just fine with night time temperatures well up into the 70's. So it's not that they can't.