Summer hasn’t been as cool as it may seem

Do you think it has been a cool summer so far in the Roanoke and New River valleys?

Most people I bump into seem to think it is.

But the statistics say it is really pretty normal on the thermometer this summer.

Both Roanoke and Blacksburg are both running about half a degree above normal in average temperature so far for June, July and the first 12 days of August.

That’s right, a hint warmer than normal.

Looking at the numbers a bit closer, it’s really more of a split decision.

Low temperatures have been running about 2 to 3 degrees above normal. High temperatures have been about 1 to 2 degrees below normal.

Average them together, and it comes out pretty close to the middle, just a hair above it.

Blacksburg’s July perhaps best exemplified the split decision on temperature. It was the seventh warmest July on record based on average low temperature (62.9 degrees) but tied for the 10th coolest based on average high temperature (80.1 degrees). The July average temperature, 71.5 degrees, was 0.3 above normal.

It seems we tend to judge summers not by averaging highs and lows, but mainly by how hot it gets in the afternoon.

Blacksburg has yet to have a 90-degree day in 2013, peaking at 89 on July 16, and Roanoke has only been as high as 94 once.

Considering the periods of extreme heat each of the past three summers have produced, it’s easy to see how this could seem a cool summer by comparison.

The reason for the dichotomy between warm lows and cool highs is the tropical humidity we’ve had on most days this summer.

Clouds and frequent showers have kept days cool, while thick humidity and cloud cover tend to hold low temperatures up at night.

But a very different air mass is moving in for the next two or three days.

A cold front that pushed through Tuesday evening has brought a Canadian air mass that will lead to low humidity levels. Highs will likely stay below 80 for two or three days, with widespread lows in the 50s, maybe even some upper 40s in a few rural locations.

However, it looks like tropical humidity will return after this early taste of fall. So the numbers for the summer as a whole are likely to end up similar to the summer so far.

Weather Journal runs on Wednesdays.

Weather Journal

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