Is the humidity really dropping or is it just less muggy? - WMC Action News 5 - Memphis, Tennessee

Is the humidity really dropping or is it just less muggy?


Have you stepped outside recently? If “feels” much better and not as muggy here in Memphis and across much of the Mid-South.

We had a cold front move through last night that is slowly bringing in drier, less muggy air. But the temperatures were still in the mid to upper 80s just like the past several mornings.

So what gives? Take a look at my snapshot of late morning dew points (in red) below. Notice the dew points were in the mid 70s before 6 AM and they dropped to the mid 60s after 9 AM. That’s why it feels so much better.

WHAT ABOUT THE HUMIDITY?  Notice that the relative humidity (highlighted in blue above) also dropped from 82 percent to 51 percent. You may think that’s due to the cold front, but the humidity actually drops almost every day.

Take a look at the weather data from yesterday (below), which was one of our steamiest days this summer. 

Notice the humidity circled in blue was 79 percent at 6 AM but dropped to 46 percent by 2 PM. It was still MUCH more muggy at 2 PM thanks to dew points in the mid 70s and actual temperatures in the upper 90s. In fact, the heat index (feels like temperature measured in degrees) was around 112º between 2 and 3 PM.

That is why dew point is a much better measure of how it feels! And while you can determine the heat index using humidity, dew point is still a better measure of the moisture content and how it really "feels". 

WHAT EXACTLY IS THE DEW POINT?  The dew point is a more accurate measure of the amount of moisture in the air at a given temperature. The relative humidity is actually measured using the temperature and the dew point. It’s actually fairly simple to see how muggy it feels outside. Take a look at the dew point temperature chart below.

Dew Point Temperature                                    How It Feels

75º or higher                                                       Miserably muggy, oppressive

70-75º                                                                Extremely muggy, extremely uncomfortable

65-70º                                                                Muggy, Slightly uncomfortable

60-65º                                                                Slightly muggy, still pleasant

60º or below                                                        Comfortable, not muggy

So when you step outside the next couple of days and notice that it feels less “humid”, just remember that it has less to do with the humidity and more to do with the dew point!

Spencer Denton
Noon and 4 PM Meteorologist
Follow Me On Twitter: @sdentonwx
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WMC Action News 5 Storm Tracking Team

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