Summer days in Greensboro are not getting hotter. The nights are. (2024)

(WGHP) — Welcome to Summer 2024. I can guarantee you it will be HOT.It always is HOT here in the summer.

Our warm season got off to a slow start this year with our first 90 degrees not arriving until last Friday, June 14, more than three weeks later than normal.Also, the 12thlatest first 90-degree day since 1903. Last year did not reach 90 degrees until July 1, the fourth latest on record.

Still, even with a slow start, we are going to make up for it with a hot stretch over at least the next week and a half with many 90-degree days.

I thought that now was a good time to take a deep dive into our summer heat history.

Highest Highs

First, let us start with the hottest temperature recorded each year back to 1903 when records began in the Triad.

You will notice from the graph that, between 1910 and 1959, we hit 100 degrees an average of two out of every five summers.

From 1960 to now, this fell back to about one summer each decade, except for the 1980s when we had two.

The last time we saw a 100-degree day was in 2012, but we hit 100 on TWO dates that year: June 29 and July 8.That was our last official 100-degree day in the Triad, so we are past due for another.

Before moving on to more of our data, there is a nearby site that has not seen a drop in extreme summer hot days.RDU has maintained a high frequency of summers still seeing 100-plus degrees.

Going back to their first year, 1888, they have always seen 100-plus-degree hottest days about every other summer and, more recently, almost EVERY summer.

This remains a great mystery to many.Whydoes RDU seem to have more 100-degree days now and GSO has less? The two cities should only be about 2-3° different, but, many days, Raleigh gets much hotter.

If you look at our list of the top 10 summers with the hottest average high temperatures, 2007 was our hottest, but only three of the top 10 came after the year 2000. Several were from the 1910s.

Average Temperatures and Lows

If you look at average temperatures, you see a different story.

Six of the top 10 warmest summers by average temperature came after 2000.That is a big number when considering that all records go back to 1903.

So if the maximum daily temperatures during summer are running lower, why is the average temperature running so much higher?

It is due to the night-time low temperatures running MUCH warmer.

We find that eight of the top 12 (I am using 12 because there are fouryears tied for ninthplace) years with the warmest low-temperature averages have been recorded since 2000.

So why are the days cooler and the nights so much warmer?

Urban Heat

During the day, temperatures are more uniform than at night. When the sun goes down, the amount of cooling depends on many factors.One of the big ones is urban sprawl.Cities hold much more heat than rural areas due to roadways and buildings.Our cities are growing and expanding rapidly.Even the airport has been growing and expanding.The cities have come to the weather sensor.

As a weather nerd, I get into things many people would never think about.Many times, even before cars had thermometers, I would go around and track temperatures at night to see how they varied.Back in the early 1980s, when I was a teen, I was the crazy guy that found a small wired temperature sensor which I put on my car dash and ran the wire out the door and mounted the sensor at my trunk.

I learned many things from doing this and you can still today see it with your car thermometer.If the night is clear, for example, with light or calm winds, you could be in the middle of a city and find 50 degrees on your temperature sensor.

Then, drive away from the city and the temperature would likely fall to below 45 degrees when you get to a rural area.If you drive to a relatively low spot, where the heavier cooler air will sink, that temperature might even fall to 40­ degrees.You should try it sometime.

That is why rural locations often see frost earlier in the fall and later in the spring than cities.