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Daytime maximum temperatures and nighttime minimums that a forecaster expects are often expressed as ranges. If the forecast covers a wide area, the highs and lows are not going to be the same in one place as in another. Besides, few forecasters would pretend that they can predict the exact degree of high and low temperatures.

Temperatures of the air are very sensitive to local conditions, such as the presence of a tree or a parking lot. The tree will keep you cooler during the day, of course, and the parking lot is hot. But these features of the landscape may have the opposite effect after dark. You may notice that the tree may actually have a warming influence on the temperature overnight, while the exposed parking lot can be especially cold. This is known as the “heat island” effect.

Temperature ranges are generally forecast in units of 5 degrees Fahrenheit, and you commonly hear these key words used to describe them:

 Near, as in near 45

 Around, as in around 20 degrees

 About, as in about 75

 Lower, as in lower 60s (60–64)

 Mid, as in mid 60s (63–67)

 Upper, as in upper 60s (66–69)

Forecasts of conditions beyond a couple of days are likely to use wider ranges of temperatures, calling for temperatures, for example, simply “in the 60s.”

Short-term forecasts for a specific area often are expressed in specific numbers, such as 70/52/74 to indicate a high of 70 degrees, an overnight low of 52, and a following daytime high of 74.

To avoid confusion, when temperatures get below 10 degrees or above 100, specific numbers are often used, even to express ranges. The forecast might be for a high of near 106, for example, or 102 to 108.