NOAA last week released data showing the Summer of 2021 in the United States was tied with 1936 for the hottest on record. When debating our changing climate, people will point out that it has been hot during Summers in the past, in particular in the 1930s. After all, Syracuse’s warmest temperature, 102 degrees, was set in July of that year.
However, there is a change taking place locally and to better gauge how our Summers have changed over the last 100 years we can focus on the Top 20 warmest Summer months of June through August (meteorological Summer)
By the middle of the last century, the list of Top 20 Warmest Summers in Syracuse was dominated by the 1930s and 1940s. 16 of the 20 years in the list came from those two decades. That’s 40% of years taking up 80% of the slots for hot summers.
Even when you tack on an additional 40 years of data and look at the years from 1903 to 1990 the list doesn’t change much. There were still 13 Summers from the 1930s and 40s in that Top 20. That’s more than 50% of the list from just those two decades.
Since 1990, however, the list has changed quite a bit. The hot years of the 30s and 40s are getting pushed out and make up only 6 of the years now. More importantly, 8 out the 20 top summers have now come in just the last 20 years and four of the Top Seven in the last 10 years including this Summer and last summer!
Even though there may have been extreme heat back in the 1930s and ‘40s, the warmth was not sustained through the entire length of the summer months where that is more commonplace in our summers now. Also, the overnight lows (which get taken into account for the overall average temperature) are becoming much warmer with this summer setting a record for warmest average low temperature.
This warming also shows up in our new 30 year averages that includes monthly increases in temperatures from late Spring through the Summer and into the early Fall.
Another way to look at all this is to highlight the Summer of 1948. After 1950 it was the 19th Warmest Summer on record and now more than 70 years later it has dropped all the way down to 55th place, pretty much in the middle of the pack.
In fact, the Summer of 1948 has dropped so much that if it occurred today, it would be considered a cooler than normal summer by more than a half a degree.