Sunday, August 1, 2010

Looking Back at July

Today marks the first day of the last month of "meteorological summer". We can finally see some light at the end of the tunnel!

Let's take a look back at July 2010...

Surprisingly, the month turned out to not be as hot for some areas.

Temperature departure from normal:

  • Cape Girardeau, Mo +1.9 degrees per day
  • Carbondale, Il +4.4 degrees per day
  • Paducah, Ky +3.5 degrees per day
  • Poplar Bluff, Mo +1.4 degrees per day

Hottest day of the month:

  • Cape Girardeau, Mo 96 on July 6
  • Carbondale, Il 96 on July 23 and 24
  • Paducah, Ky 98 on July 24
  • Poplar Bluff, Mo 97 on July 29

You get the idea from the data above that it has been a bit hotter in southern Illinois and western Kentucky. Keep in mind, the thermometer might not have read higher, but it was hotter as compared to what the normal temperature should be.


The main culprit for it feeling so hot last month was the humidity. When I am talking about humidity, I am referring to the amount of moisture in the air. The best measure and indicator as to the humidity is the dew point temperature. In basic terms the dew point is the measure of the amount of moisture in the air. (Go here for a full definition of dew point.)

As I often say on the television, dew points above 60 degrees starts to make it feel uncomfortable outside. Dew points over 70 degrees makes it feel tropical/very uncomfortable. Dew points through the month of July have been sitting in the middle to upper 70's. That is very humid air. Typically in late July and August we will see dew points in the mid-70's. A couple days I saw the dew point hit 80 degrees which is about as high as you will see. (A few times during the summer you can find dew points in the lower 80's in Iowa over the corn fields.)

The dew point is used with the air temperature to calculate the heat index, or the "feels like" temperature. The heat index seems to have been sitting in the lower 100's throughout much of the month. I think the highest I saw it get was around 113 (in Mt. Vernon, Il).

So has it been a hot month? Generally speaking.... A little. Has it felt hot? ABSOLUTELY!

July also turned out to be relatively dry. If I had a nickel for every time someone has told me, "It hasn't rained here all summer. It will rain two blocks from my house, but not at mine. Bring me some rain." I could be sitting on a beach sipping drinks with no worries.

Let's take a look at July's rainfall numbers.

Precipitation departure from normal:
  • Carbondale, Il -1.85"
  • Paducah, Ky -3.09"
  • Poplar Bluff, Mo +0.40"

As you can see, it again depends on where you live. Some areas have been around normal and others have been well below normal.


It is interesting to compare the precipitation departure from normal to the temperature departure from normal. Notice that the areas that are well below normal for rainfall are the areas that are quite a bit above normal for temperature. This is not abnormal. In fact, it is to be expected.

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