DENVER — Using a measurement of humidity called the dewpoint temperature, the last few months have been among the most humid in 20 years on the Front Range and eastern plains.
In May and June, a persistent blocking high pressure pattern brought in extra moisture from the Gulf of Mexico. That meant high humidity and record-breaking rainfall for much of the eastern half of the state.
In May, the average daily dew point temperature at Denver International Airport (DIA) was the highest it's ever been since the station was installed in 1995. And the average dew point in June was second highest only behind 2015.
That blocking high pressure has moved to the west in July, but now the hot sun is evaporating all that moisture left on the ground from the previous weather pattern. Keeping the humidity levels high.
So far this July, DIA has had the highest maximum dew point temperature since 1999, and the daily average is close to record levels behind 2009 and 1998.
The humidity actually helps keep temperatures down, and it’s the main reason Denver did not make it to 100 degrees on Monday. If we had our normal lower dewpoints, it would have likely hit triple digits.
But on the other hand, humidity raises the heat index or what’s sometimes called the “feels like” temperature.
If it was 96 degrees but there was a high dewpoint of 66 – then the heat index would be 100 degrees. It would feel hotter than it actually is.
And in dry heat, it would be the opposite. A 100-degree temperature with a dewpoint of 40, would make it feel like it was just 95 degrees.
The humidity in Colorado has been high, but not high enough to cancel out all our “dry heat” benefits – at least that's true on the on the Front Range.
For example, when it hit 97 degrees in Denver Monday, the dewpoint of 45 still made it feel like 93 degrees.
ARIZONA
Another part of the country that would normally claim the benefits of "dry heat" is Arizona. Well, they've been dealing with even higher humidity lately, especially during this first surge of the summer monsoon.
It's even being high enough to cancel out any of the "dry heat" benefits. When it hit 116 degrees there Monday, it still felt like 116 degrees because the dew point was 56 degrees at the time.