After I finally received my WeatherProof cover I immediately noticed an accelerated temperature gain in the SweatTent XL. The Tent truly got to 185 within 30 minutes from start of Fire. The WeatherProof cover clearly assists in keeping the heat in the Tent and does not allow the Heat to escape out vertically. if you did not get one for your Sweat Tent I suggest the purchase. If you are waiting for the arrival of you Weatherproof cover, I assure you it will be worth it !!!!!