Record dewpoints in MN in July!

[PurdueWx80]

Fascinating read, especially the part about the highest dewpoints on the planet, and in the US. For those who don't know, dewpoints can get so high in the Midwest because of evapotranspiration from corn. While most of the Midwest is in a drought parts of western IA and much of MN has been quite wet this year. Read on...

From the Minnesota State Climatologist...

Subject: New State Record Dew Point Temperature Set July 23, 2005.

Unusually high dew point temperatures pooled over southern Minnesota during the late afternoon and evening hours of Saturday, July 23. Both Pipestone and St. James reached 86 degrees at 5:00 pm, breaking the old record of 84 that was set at multiple locations on July 20, 2002. During the evening hours on that date, three west central Minnesota locations; Madison, Morris, and Olivia reported dew point temperatures of 84 degrees. Our examination identified one other episode of such extraordinary dew point values. A handful of southern Minnesota locations reported 84 degree dew point temperatures on July 29 and 30, 1999.

Note that there has only been about ten years of higher density hourly dew point temperature readings for Minnesota. The bulk of the automated weather stations were installed in the early to mid 1990's. The Twin Cities has hourly dew point records going back to 1945.

The dew point temperature at the Twin Cities International Airport on Saturday, July 23 topped out at 80 degrees at 9pm. 80 degree dew point temperatures are rare in the Twin Cities historical record. Since 1945, there have been only twenty-one hours of 80 degree dew point temperatures recorded. Ten of those twenty-one hours came in a ten hour period on July 12 and 13, 1995. The highest dew point temperature ever recorded in the Twin Cities was 81 degrees at 11:00 am on July 30, 1999.

Dew point temperatures in the low 80's can occasionally be seen across the Gulf Coast and the Upper Mississippi Valley. A handful of locations in the United States have seen dew points as high as 90 degrees F, especially in Florida and Louisiana. Some of the highest combinations of dew points and temperature on earth can be found in the costal regions of the Persian Gulf, the Gulf of Aden and the Red Sea where dew point temperatures as high as 93 degrees have been measured.

The heat index, a "feels like" measure which factors together temperature and dew point temperature, reached 125 degrees at Pipestone, MN at 5:00 pm on July 23. At that time, the air temperature was 93 degrees and the dew point temperature was 86. A quick scan of the historical database reveals only one other heat index value of 125 degrees. An air temperature of 97 degrees teamed with an 84 degree dew point temperature to create a heat index value of 125 degrees at the Red Wing airport at 3:00 pm on July 30, 1999.

[EDR1222]

That is interesting about the high dew points being related to corn! Those are some really high heat indexes as well.

We don't ever see anything like that here in Florida as far as I know. I don't even think during the heat wave of 1998 that we had anything like that.

Very interesting read!

[Aslkahuna]

Dewpoint values in the low 80's can also occur along the Colorado River Valley and in the Imperial Valley of SE CA.

Steve

[PurdueWx80]

Dewpoint values in the low 80's can also occur along the Colorado River Valley and in the Imperial Valley of SE CA.

Steve

Where in the CO River Valley - near where it exits into the GOC?

[Aquawind]

Wow..125F Combine that with mosquitos the size of geese and I am feeling pretty good about things in SW Florida..lol Not missing that stuff at all..

Thanks for posting that.
Paul

[Aslkahuna]

They have been recorded as far north as Needles. The SE CA stations and AZ stations including PHX and PHX see mid to high 70 dewpoints every year during the monsoon.

Steve

[ict1523]

We had 80 dewpoints for a day here too in July.

[Jim Cantore]

same here

[Hurricaneman]

Same thing here, I call it the yuck factor

[OklahomaWeather]

Yikes, I grew up in Owatonna, MN, which is a little over an hour from St. James. I showed my horse in horse shows every summer, and I can remember some of those MISERABLE shows where the dew point climbs to ungodly levels... I now live in Oklahoma and the heat is no where near as bad as Minnesota!

[azskyman]

Phoenix had a dewpoint of 73 this morning, so it is a soupy one here too. Having come from Illinois, it seems strange to hear those numbers in a forecast that also stated "We'll struggle to hit 100 today with all the humidity in the air!!"

[Aslkahuna]

Dewpoints were even higher down around Yuma and Gila Bend (mid to upper 70's).

Steve