Different ways of measuring heat

AUSTIN (KXAN) - The heat wave is hard to ignore.

Temperatures readings come from many different places. You see the triple-digit numbers in your car and on roadside billboards. Often that temperature is different from the one we report out of the First Warning Weather Center .

Thermometers attached to buildings often display higher temperatures because of the heat the building radiates. The same goes for the reading in your car.

Official temperature readings from the National Weather Service come from Automated Surface Observing Systems . In Austin, there is one at Camp Mabry and at Austin-Bergstrom International Airport. There are specific ASOS location requirements that ensure more accurate readings.

The temperature and dewpoint sensor in a ASOS weather station is mounted five feet above the ground. It is protected from the elements, like direct sunlight and rain, but is kept well ventilated. Surrounding buildings or concrete cannot influence the reading and have to be 100 feet away. Even the grass or vegetation near the station is kept shorter than 10 inches.