Why is it sultry before a thunderstorm?

1, it was sultry before the thunderstorm because the ground temperature was very high, the air was humid and the weather was sultry before the thunderstorm.

2. This is because the ground temperature in thunderstorm weather must be very high, and there is more water vapor in the air, so that the humid air will rise and form cumulonimbus clouds at high altitude, and thunderstorms may occur. Therefore, before the thunderstorm comes, it is bound to feel sultry.