A look at weather extremes and the big-picture climate connections.

March Heat Wave Shatters Monthly Records

For tens of millions of Americans, 2012 will be remembered as the year that summer came early. The month of March shattered all-time monthly warm temperature records for many locations from the Upper Midwest to New England, with many places beating their old records by several degrees. 

For March as a whole, more than 7,000 daily record high temperatures were set or tied, and a nearly equal amount of warm overnight low temperatures were reached. In recent years, record daily highs have been outpacing record daily lows in a pattern that has been shown to be inconsistent with natural climate variability alone. So far in 2012, the daily record-high to record-low ratio has been 17-to-1 through March 27, for monthly record highs compared to monthly record lows the ratio has been a whopping 33-to-1 in favor of warm temperature records. If the climate were not warming, one would expect the ratios to be closer to 1-to-1.

March temperature departures from average during March 2012. Credit: Midwest Regional Climate Center.

According to the blog Capital Climate, 110 cities in 33 states set monthly high temperature records during March.

For example, in Minneapolis, March was by far the warmest such month on record. Here’s how the National Weather Service described the statistics: “The departure from normal for temperatures this past month were just staggering, with most of Minnesota and Wisconsin seeing the average temperature for the entire month end up being double digits above normal.”

In Minneapolis, the average temperature for the month was 15.5°F above average, beating the previous record set in 1910. March saw the earliest occurrence of an 80 degree temperature on record in the Twin Cities, on March 17, and the greatest number of 70 degree days during the month as well.

In Detroit, the mid-March heat wave was enough to vault the month to the top of the list of warmest Marches on record. Not only that, but the records for the most consecutive March days with highs above 60, 70, and 80 degrees were also set.

Chicago easily set a record for the warmest March, after breaking or tying daily high temperature records on nine consecutive days from March 14-22 — the second-longest stretch of daily temperature records of any type for the Windy City dating back to 1871. The previous warmest March on record there occurred in 1910 and again in 1945, when average monthly temperatures were 48.6°F. March 2012 far exceeded that, averaging 53.5°F. If this had been April, that average monthly temperature would have been high enough to rank as the seventh-warmest April on record there.

The 4.9°F temperature difference between the warmest and second-warmest March on record may seem small at first, but it actually was “... By far the largest difference between first and second place between record warm or cold months in Chicago,” the NWS stated.

In Chicago, there were eight days that reached or exceeded 80 degrees during the month. Prior to this March, the Weather Service reported, there had been just 10 days in March with highs in the 80s. In other words, 44 percent of Chicago’s 80 degree March days since 1871 occurred in March 2012!

The warm March helped 2012 get off to the warmest start on record (January through March) in Milwaukee and Madison, Wis. Both cities had their warmest March on record, with average temperatures of more than 4°F above average in both locations. In addition to setting numerous daytime high temperature records, Milwaukee tied or broke record high minimum temperatures for six days in a row during the heat wave.

The heat extended to the East as well. Albany, N.Y., had its warmest March, as did Buffalo. New York City's Central Park narrowly missed setting a new March record, but it was the warmest March at JFK Airport, La Guardia Airport, and Newark.

In Buffalo, the average temperature for the month was warmer than the typical average temperature for the month of April. Like many other locations from the Upper Midwest to the East Coast, Buffalo set an all-time monthly high temperature record when temperatures reached 82°F on March 21. The warm weather caused water temperatures in the Great Lakes to climb to levels never before witnessed so early in the year. The water temperature on Lake Erie at Buffalo reached 40°F in March, which was the first time that has occurred since records began in 1927.

Tulsa, Okla., and Ft. Smith, Ark., also saw their hottest Marches on record, with both cities finishing the month a little more than 10°F above average.

Other cities that set monthly records during March include: Atlanta, Bismarck, N.D., Burlington, Vt., Cincinnati, Cleveland, Des Moines, Indianapolis, Kansas City, Nashville, Pittsburgh, Roanoke, Va., Syracuse, St. Louis, and Washington, D.C. (H/T Washington Post’s Capital Weather Gang blog).

Parts of the South were unusually warm as well, with Atlanta setting a record for the most 80 degree days for the month of March.

More resources:

Track record temperatures using our interactive Record Tracker
What role might global warming have played in the March heat wave?

« Extreme Planet