First Alert Weather in detail: How to measure a heat wave

ROCHESTER, NY — It’s highly unusual to see large temperature swings this time of year. But this season has been a little different. Recently, Rochester had temperatures as low as 10 degrees, but there will be a major change in the overall weather pattern early next week when the jet stream shifts on Monday, Tuesday and Wednesday — and that will bring a tremendous amount of heat and humidity back to Western New York.

On those hot days, it can be fun to measure how high the temperature gets during a heat wave. However, quite often there can be a significant difference between the temperature in your home or car and that at Rochester Airport. Why the difference?

This temperature is made up of many factors, but the variance can also be due to how and where we place the thermometer. Rochester Airport uses an instrument shelter, which, as the name suggests, is always protected from sunlight and precipitation. The thermometer at your home might get a little direct sunlight, creating an artificial reading. The airport shelter is painted white and has ventilation, which also reduces heat absorption. The thermometer at your home might be near dark colors that can absorb more heat. Also, the airport measures the temperature 4 feet above the ground and is over an open grassy field. Your temperature sensor, on the other hand, might be mounted over concrete or asphalt, which is not an ideal setting for accuracy.

I remember watching a baseball game on TV in Kansas City, Missouri, “back in the day” in the heat of summer. The TV station said it was 49 degrees on the field. They showed one of those thermometers that was on the artificial turf and measured the temperature directly in the sunlight. This is an extreme example of artificial temperature measurement.

Remember: To get truly accurate results, how you protect your thermometer is crucial.