Recently my department aquired a building to drill on. Unfortunatly we aquired it during some of the hottest days of the 2010 summer and the days were limited for training. The drill chosen was roof ventilation. So the question is; Is it acceptable to drill outdoors on days when the heat index meets or exceeds temps of 85 degrees or greater? (just to put a number on it) And yes I know we fight fires in the heat, the difference is we can't control fires but we can control drills.