Last time we checked in with the Great Lakes, it was in the bone-chilling depths of the Polar Vortex, and a record-breaking 88 percent of the lakes were frozen. Now, here we are, at the end of April, and the lakes are still 30 percent frozen, which could mean a colder summer for the country.

The icy lakes have already created all sorts of economical and environmental headaches for the region. Most obviously, shipping has been affected, with boats still needing to use ice breakers to access some ports. Certain birds and fish are still not able to get to the food or spawning grounds they've usually reached by this time in the season. Now here's a new development that will almost certainly not be welcome by the Midwesterners shivering in their sandals: The Washington Post analyzed historical data from NOAA and noticed that the years with greater ice coverage on the lakes also saw lower summer temperatures.


Chart by Matt Rogers for the Washington Post, using NOAA data

The iced-over lakes don't act like a natural air conditioner, per se, rather the weather patterns that created the Polar Vortex in the first place are more likely to stick around in the years of heavy ice. Now remember the fact that this is the most ice researchers have seen on the lakes in late April after 30 years of record-keeping. Get ready for some polar bear swims on the 4th of July. [Washington Post]

Ice breakers on Lake Superior this week by John L. Russell/AP