A heat burst caused the the temperature to rise from 70° in Monticello, Iowa to 86° in a matter of minutes. Heat bursts often occur in decaying thunderstorms and are a result of air descending from a storm and rapidly warms as it lowers. Warm, dry and gusty winds are also associated with heat bursts. The dewpoint dropped from 64° to 50° in the same time frame. While relatively rare sometimes heat bursts can result a quick warm up of 25° or more!