86° in late August, Below Normal?

By: METEOROLOGIST MARK HENDERSON
By: METEOROLOGIST MARK HENDERSON

Wednesday's high temperature reached 86°. The normal high temperature for August 22 is 82°. Yet, when the book closes on today, it'll go down as a BELOW normal day... How in the world can that be???

True, our high temperature was 4° above normal, but our morning low temperature of 51° was a whopping 10° below the normal low of 61°! When we discuss a day being above normal or below normal, we have to consider both the High AND Low temperatures. In this instance, we take an average of the high and low temperature, and compare it to the average of the normal high and low temperature.

So, let's do the math! Today's high of 86° + Today's low of 51° = 137°. Divide that by 2 and you get today's average temperature of 68.5°.

Now, the normals. Normal high: 82° + Normal low: 61° = 143°. Divide that by 2 and you get 71.5°.

Finally, compare the two numbers... Today's average temperature of 68.5° is below the normal for the day by 3°! So that, my friends, is how you can end up with a day as warm as Wednesday was still end up below normal.

So, how does this happen? The primary contributor to scenarios like this is low humidity. Dry air heats very quickly, and also cools very quickly! The opposite can be said in times when we have an all-day and all-night rain or snow event. The clouds will keep the temperatures below normal during the day, but much above normal overnight. The end result could be a day with below normal highs, but an overall above normal temperature!


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