With June in the books, we're guessing a centerpiece of your holiday weekend conversations will be whether or not we're on track to replicate the glorious summer of 2015.
The answer: probably not, but it might be close, according to the first batch of data from the Minnesota state climatology office’s Summer Glory Index.
Several spurts of sweltering temperatures, muggy evenings and heavy rain kept last month from replicating the near-perfect weather of June 2015.
In one month alone, we’ve already had four days at or above 90 degrees this year in the Twin Cities. That’s the same number we had over the entire summer last year.
This perennial Minnesota debate is a little less subjective thanks to the state climatologists.
Last year, they wanted to know if June — with its abundance of sunny days and pleasant temperatures — was truly unusual. So they thought it would be amusing to quantify and rank summer weather by pleasantness.
The Summer Glory Index examines average high and low temperatures, humidity (dew point) and precipitation. It then uses these four categories to score each day’s outdoor comfort. Each category accounts for 10 points of the day’s overall score, with the most “glorious” days earning a perfect 40.
“It essentially helps us score the extent to which our days were comfortable, our nights were sleep-able…and if we weren’t drenched by our own sweat,” said Kenny Blumenfeld, senior climatologist with the Minnesota Department of Natural Resources.
By the index’s standards, an ideal summer day boasts a high temperature in the 70s, a low in the upper 50s or low 60s, a dew point of less than 60 and no rain.
There’s also a “fail point” for rotten days. For temperature, a day is considered a “fail” if the high temperature exceeds 90 degrees or remains below 60 degrees. Points are deducted if a day reaches those limits.
According to the SGI index, June 2015’s gloriousness helped make summer 2015 the third best summer on record.
Minnesota’s SGI scores go back to 1903, but the data only accounts for conditions in the Twin Cities.
Historically, Minnesotans enjoyed the most “glorious” summer in 1922, followed by a second-best summer in 2008.
The scorching heat of 1936 secured its ignominious position as the worst summer on record, while humidity sealed the fate of the summer of 1983, ranked second-worst.
Good — and awful — summers tend to come in multi-year groups, and Minnesota is the middle of a comfortable stretch, Blumenfeld said.
And what can we expect in July and August? Can the historical Summer Glory Index data give any hints of what's ahead?
“That’s not a scientifically knowable question,” Blumenfeld said.
Some glorious Junes have been followed by dreadful weather in July and August. Similarly, miserable weather in June doesn’t necessarily precipitate a terrible summer.
“It’s almost like tracking baseball stats,” Blumenfeld said. “You have no idea.”