METEOROLOGIST JEFF HABY
Sometimes the temperature reported in the media is from a single reporting station. This measurement may be at a TV
station, from a nearby airport or another official temperature station. The reported temperature
will often be different from the temperature someone measures in their backyard. This Haby Hint
will explore the reasons why.
To start, the reason could be something obvious such as:
1) Broadcasted temperature is not a current temperature
2) Temperature station is far away (i.e. on the other side of a cold front)
3) Temperature error, thermometer not calibrated correctly
The temperature that someone measures in their backyard may be significantly different from that
reported through the media. Reasons for this when the backyard thermometer is the problem include:
1) Thermometer is too close to the house. Heat or cooler air from the house can contaminate the measurement.
2) Thermometer is in direct sunlight. A thermometer in the sunlight will read much too high. The official
temperature measurement is made in the shade.
3) If thermometer is close to metal it will read too high when the sun is out.
4) The thermometer should be about 5 to 6 feet off the ground since the official measurements are taken
near this height. Thermometer may read too warm in the day if it is too close to the ground and too
cool during the night if it is too close to the ground.
There are additional factors that can cause the temperature measured in the backyard to be
different from the official measurement and they include:
1) There could be elevation differences between the two thermometers. It tends to get cooler
with height. However, in some cases it will warm with height such as when an
inversion is present.
2) There can be different weather on a different side of town (i.e. thunderstorm over one of the stations).
3) Commonly there are urban and rural temperature differences. Rural areas tend to be cooler.
4) There could be a lake, ocean breeze or some other mesoscale process that produces a temperature
difference over distance.