People living in the interior Western United States have a skewed sense of humid air. This was made clear to me early this week when I came across a graphic from a meteorologist in Idaho describing different humidity levels.

At first, I thought maybe the graphic was a joke or perhaps mislabeled. Humidity levels that Washingtonians would consider dry and refreshing were described as “yucky” and “sticky.”

The graphic, developed by chief meteorologist Brian Neudorff from affiliate KMVT in Twin Falls, displays ranges for a measure of humidity known as dew point and then describes how they feel.

The higher the dew point, the more humid it is.

Dew points above 61 degrees are called “miserable.” Consider then that a “miserable” day in Twin Falls would be less humid than a normal day in D.C. at this time of year. (The average dew point in D.C. on June 29 is 63 degrees compared with around 50 in Twin Falls. On Wednesday, the dew point hit 75 degrees in D.C. whereas it was 40 in Twin Falls.)

Even dew points ranging from 41 to 45 degrees are labeled “noticeably humid” for Idahoans. Dew points at such levels in D.C. during summer would be considered exceptionally dry, and half the city would be taking a mental-health day.

To get a sense for the stark differences in perceptions of humidity between Idaho and D.C., look at the corresponding dew-point graphic we developed for our region:

D.C.’s “pleasant” and “still comfortable” humidity levels are Idaho’s “sticky” and “muggy.”

Of course, residents of South Florida would probably say Washingtonians also have a warped sense of humidity.

Brian McNoldy, Capital Weather Gang’s tropical weather expert who resides in Miami, notes its average dew point on June 29 is 73 degrees — 10 degrees higher than D.C.’s. Dew points in the 60s in summer in Miami are rare and more characteristic of winter months.

Miami’s average dew point is 70 degrees or higher on 144 days of the year, from May 25 to Oct. 16. D.C.’s average dew point never gets that high (although we certainly have days in which the dew point hits or exceeds 70).

It’s interesting to note, however, that D.C.’s most humid days — when dew points hit the upper 70s — are comparable with Miami’s. In other words, Miami has much higher average humidity, but our maximum extremes are similar.

“I think the comfort scale in D.C. applies here [in Miami] as well, it’s just that we spend WAY more time in the ‘sultry’ category,” McNoldy said.

He said he would tweak D.C.’s dew-point scale for Miami, accordingly:

Under 60°: Pleasant (mid-winter happiness)
60-65°: Acceptable (still wintry)
66-71°: Moist (“snowbirds” leave)
72-77°: Sticky (instant sweat)
78°+: Oppressive (steam sauna)

Ultimately, how humid it feels is subjective and dependent on the climate you’re accustomed to. Land-locked Idaho with its prevailing continental winds just doesn’t experience moisture levels common in D.C.

South Florida, which is surrounded by water, has the highest average humidity in the Lower 48.

Still, it is very interesting to see how humidity is communicated and perceived in these locations and the remarkable differences place to place.

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