Summer Polar Vortex vs. 2009 Year Without a Summer?

There's much ado this week about the Polar Vortex giving a dose of chilly weather to the Midwest in July. Whether or not it's really the polar vortex can be debated, but the point is that temperatures are being socked way down below normal this week, and it's especially impressive because this is the time of year the area should be experiencing their warmest days of the year! Here's a map of forecast low temperatures (NWS) during the next four days:

So when's the last time this happened? What many people may not remember is <a href=" the 2009 July cooldown, which set over 7,800 low temperature records (NCDC) and caused a chilly July the likes of which had not been seen since 1993.

The map above shows the 2,009 (ironic, right?) record low minimums broken that month. Some called 2009 "The Year Without a Summer" (though it didn't really compare to the real Year Without a Summer in 1816). In seven states, it was the coldest July in recorded history.

It's unlikely that July 2014 will get close to the same level of chilliness as 2009, but this week's outbreak is nothing to sneeze at. Some of the negative departures from normal are as low as -5.4 to -6.3 so far this month (highlighted on the map below) but it's still early in the month. The same map I posted in July 2009 for the first 23 days of the month showed similar numbers over a much wider area, and departures as low as -8.7!

This may reinforce the trend that cold records were exceeding warm records earlier this year, and that global temperatures continue to maintain the slow upward trend that started in the late 1990s (as I blogged in March). Some specifics on just how cold this week's temperatures will be in the Midwest, from our Polar Vortex Infographic story:

A few other random tidbits that describe the (relatively) cool Summer that some of us in the Northeast and Midwest are having:

- Icebergs were still present in the Great Lakes in mid-June, when the ice ended its latest-on-record season

- New York City didn't hit 90 degrees until July 2nd, later than any year since 1985.

- Cold air sweeping in behind Hurricane Arthur on July 4th (which ran up the coast like a Fall Nor'easter) caused snow to fall in the mountains of Maine