Taking a glance at our scorching summer so far: how it’s affecting our Great Lakes

Weather Blog

Our summer so far has indeed been quite the warm one. Remember when we talked way back about having a particularly hot summer in Rochester? Turns out NOAA was pretty on track. You can check out the earlier blog post here.

As we get closer to the end of meteorological summer, I thought I’d take a glance at some of the numbers so far. It’s no surprise we’ve endured a very warm summer and a scorcher of a July.

Here’s our calculated average temperature so far for this summer:

From June 1st through now our summer has proven itself with many hot and dry days. 71.8°F may not seem like that warm of a temperature, but when we’re talking about the average of all the days in summer it settles fairly high in the ranks. To be exact, since 1926 only 7 summers have been warmer than this one.

How did we get this number? We took the AVERAGE MONTHLY temperatures for June, July, and August (thus far) and averaged those numbers together to get this.


Look at the average monthly temperature for July of this year. The average monthly temperature ended up at 75.6°F. When all was said and done that month sat at being 4.8 degrees warmer than normal. It also ended up being one of the top 5 hottest July’s on record.

Has this affected our lake temperatures? You bet it has. Our Great Lakes are sensitive to both the warm and cold temperatures in ways that heavily affect our local weather and climate. 

Our Great Lakes gradually get warm in the summer and peak around August, and eventually get cold enough to freeze in the winter. Why? Good ol’ specific heat.

The graph below shows the average surface water temperature for Lake Ontario in both 2020 in red, and the average from 1995-2019 in purple

You can see how the lake compares to the overall average lake temperature throughout an entire calendar year. Notice how much more it’s spiked above the average during this year’s summer months. It shows that our lake peaked at a temperature around 78 degrees at one point during the month of July. 

Below are Great Lakes Average GLSEA Surface Water Temperatures of Lake Ontario over the past 5 years. 

Courtesy: https://coastwatch.glerl.noaa.gov/statistic/avg-sst.php?lk=o&yr=0

When comparing the surface water temperatures over the past 5 years, the 2020 line shown in black has notably peaked the highest out of all 5 of the past years. Other years such as 2016 and 2018 have come very close, but not quite.

Personal thoughts:

Although we fall within the top 10 warmest summers for the time being, our likelihood of having a below average trend anticipated by the Climate Prediction Center (CPC) for the next 6-10 days might deter that just a little. Will it be enough to bring our summer average down? Only time will tell. Regardless, we’re still on a decent path to being one of the top 10 warmest summers since the start of record keeping.

CPC 6-10 Day Temperature Outlook

We have 18 days left of meteorological summer to go…18 days before we determine if this summer is one for the record books.

Another final, parting thought:

Rochester, NY is known to be one of the snowiest cities in the entire country. What helps us keep our snow totals high every year is a phenomenon we’re all too familiar with: lake effect snow.

The reason we have lake effect snow is because of our unique climate and position relative to our Great Lakes. As cold air from the arctic flow over our warm lakes from the heat of the summer, it creates the perfect environment for lake effect snow to pile high all winter long.

Could these especially warm lake temperatures impact our winter giving us a more active start to lake effect season? It very well could, and if I had to bet money on it I’d get gutsy to say we may be in for an interesting start to the cooler season, although we’ll have to wait and see what the atmosphere ultimately holds for us. Stay tuned!

~Meteorologist Christine Gregory 

Copyright 2020 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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