High Dew Points

posted in: Michigan Weather Forecast, Slim | 8

High Dew Points

Boy it sure was humid on Tuesday (August 10) The highest reported Dew Point in Grand Rapids on Tuesday was 79. Now one might think that would be a record high DP and while it is indeed on the upper edge of how high the dew point can get here in Grand Rapids, but it has gotten that high on several days in the past.  This past week might not be a true “heat wave” but it sure was a true “humid wave” I now have found a web site that keeps records of past dew points. And I looked back to 2001 and I was surprised to see that in all of the summers from 2001 to 2021 there have been days with the dew point has reached the mid to upper 70’s in each of the past summers (at least 2009 to 2021) This year the highest reported dew point at Grand Rapids has been 79. But this year July had a dew point of 76 and back in June there was dew point of 75 reported. So how dose this year stack up to past years?

In 2020 in June there was a dew point of 75, in July 76 and in August 75. In 2019 June 69, July 78, and August 73. In 2018 June 78, July 75, and August 76. In 2017 June 72, July 73, and August 73. In 2016 June 72, July 76 and August 74 in 2015 June 74, July 74, and August 73. 2014 June 72, July 75 and August 77. 2013 June 70, July 75 and August 74. 2012 (a very hot summer) June 73, July 75 and August 73. 2011 June 74, July 77, and August 76. 2010 June 72, July 76, and August 76. 2009. July in 2009 was a very cool July and that year June 71, July 67, and August 74. In 2008 June had a dew point of 75, July 74 and August 72. In 2007 June had a 74, July at 72 and August a 74. In 2006 June 71, July 77, and August 78. In going back more the highest dew points for the year were in 2005 77 on July 24th in 2004 77 on July 22nd in 2003 78 on August 21st in 2002 78 on July 21st in 2007 79 on August 7th on that day the air temp was 90 with that DP of 79 for a heat index of 106. In fact, most of the years the day of the highest dew points were on days with higher temperatures than we had this month so far. Bottom line is that dew points in the mid to upper 70’s happen here in Grand Rapids on a regular basis most summers.

Here are some past days at Grand Rapids with high heat indexes. 2021 highest 100 August 10 (100) 2020 July 17 (100) 2019 July 20th (107) 2018 June 30 (105) 2012 July 6 (112)

Here is a fun fact August 1992 was the coolest August of record here at Grand Rapids but on August 10th that year at 2 pm and again at 4 pm the temperature was 85 with a dew point of 76 good for a heat index of 95.

Now for the highest Dew Point that I can find for Grand Rapids that was at 5 PM on July 13, 1995. At 5pm the air temperature at Grand Rapids was 97 and the dew point was 81 yes that is right 81 and the heat index was 120. On that day the temperature reached 91 at 1pm with a DP of 79. At 2pm the temperature was 92 with a dew point of 80. At 3pm the temperature was at 94 with a DP of 80. At 4PM the air temperature was 95 DP was 80. At 5PM air temp 97 DP 81. At 6PM air temp 96 DP 79 It stayed that way to 9PM when the temperature had fallen to 92 with a DP of 79. At 11PM the air temperature was down to 84 and the DP was still at 79. The next day was not much better with the air temperature of 83 and a DP of 80 at midnight. By 2AM the temperature was back up to 85 with a dew point of 79. The overnight low was 81 at 6 AM with a dew point of 80. At 1PM the air temperature was 94 with a dew point of 80 The high for the day was 97 with a dew point of 77. Now that is what I would call a big-time heat wave of two days.

Slim

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INDY
INDY

Beautiful coming home to temps in the mid 70’s feels like air conditioning compared to 90’s and heat index in the mid 100’s hot hot hot …In Florida!! The no 90’s degree days continue what a streak I can see September it’s coming on fast Summer is slipping away just like our data …INDY

Mark (East Lansing)
Mark (East Lansing)

Three weeks ago, we were at Lake of the Ozarks. It was mid 90s all week with heat index of 100-105. We rarely left the water. Beautiful part of the country.

Perfect day today at Silver Beach in St. Joe. Lots of people and lots of boats on the water.

Barry in Zeeland
Barry in Zeeland

Good find Slim! It would appear that a dew point of 80 or better is pretty rare around here. As for the DP being in the 70’s every year, I think it would need to be looked into how long it stayed there. As in how many days in a row. Like this past week it was day after day in the 70’s, not just 1 day or 2 days, but about a whole week. Anyways, interesting data to look over! One other thing, just imagine how hot 2012 would have been with dew points at 80!

MichaelV

Thanks for all this info Slim – had to read it a couple of times to process. Seems I can remember a lot of hot and humid days back in the 50s and 60s when I was growing up, of course, that was back before people had air conditioning in their homes so it probably stuck with me. Geez, I am getting old…