It’s Not the Heat but the Dew Point

We have all heard the old saying “it’s not the heat, it’s the humidity”, you may have even said that these past few days, but what you really should be saying is “it’s not the heat, but the dew point”.  Relative Humidity is exactly that, relative and is directly correlated to the air temperature.

Instead, you feel uncomfortable base on the amount of water vapor in the air, which is not what relative humidity is measuring.  The past few days the relative humidity has dropped to around 50-60% during the afternoon when the heat indexes were at the highest point of the day.

A better way to know what your comfort level will be is to watch the dew point and remember that dew points in the 40s you’ll be feeling great, in the 50s, you’re still comfortable, moving through the 60s, most feel slightly uncomfortable, but when the dew points are in the 70s (the case the past few days) no matter what the temperature, nearly everyone is uncomfortable and the word sultry will probably come to mind.

7 thoughts on “It’s Not the Heat but the Dew Point

  1. Weather forcasters give the dew point all year. In winter they will say (for example) that the dew point is 25(F). How can you have dew below freezing? Would that be the temperature at which you would see frost?

  2. Have we ever had a morning low as high as on Sunday morning when the morning low was 79?

  3. That 70s category sounds familiar. Just got back from a couple weeks in Belgium where high temperatures were only in the 70s. Plus lots of rain and clouds. Walking out of airport in Florida felt like an oven in comparison, but also good. No place like home!

  4. The record is 82˚ in Fargo for a low. The thing is what that 79˚ low, the official low ended up being 73˚ that day as the temp dropped to 73˚ at 11:59. Likely the same will happen today, the low this AM was 80˚, but it should be much lower than that at midnight for the official low.

  5. Paul, I have made “jokes” about that myself, but yes, it is technically the frost point from 32 and below, but the vernacular is to still refer to it as the dew point.

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