May 23, AM Update: Thanks to the comment from Anonymous, who points out that the spring 1910 chart originally posted was in degrees F, whereas the 2012 chart was in degrees C! (So much for taking the default plot options from the same web site.) This means that the comparison is not even close. Barring a supernatural "Day After Tomorrow" event in the next 8 days, the U.S. spring temperature record is a complete lock by an incredibly wide margin. Beating a 3-month record over a continent-wide area by such a large amount is so unusual that it didn't look that strange to be comparing Fahrenheit and Celsius. (For the non-mathematically inclined, the conversion factor for F to C is 9/5, or 1.8, so in rough terms, the 2012 anomaly to date is beating the old record by an astounding 80%.)
The 1910 chart below has been updated to degrees C.
Following closely on the heels of the third warmest winter and the warmest first quarter, Washington DC is well on its way to the warmest spring on record. The record warmest March was followed by a less extreme, but still above-average, April, and May has rebounded to 4.2° above average. Only 2 days so far this month, the 10th and 11th, have been below average, and that was by just 1° each.
Even without a boost from the expected near-90° temperatures in the upcoming holiday weekend, the March-May average temperature to date of 61.2° is cozily above the current record warmest spring of 60.7° in 1977. Since the normal daily low temperature is near or above 60° for the rest of the month, it would appear that the record is virtually a lock. In fact, applying the forecast temperatures for the next 7 days and the climatological averages for the 29th-31st, the projected final spring average would be 61.8°, which is over 1° above the previous record. This is a bigger margin than the difference between the current 4th place spring (2004) and the 10th warmest (1980).
Looking more widely, the predicted above-average temperatures over most of the U.S. east of the Rockies through the end of the month could contribute to the warmest spring on record for the contiguous 48 states. According to National Climatic Data Center (NCDC) records, the warmest spring occurred in 1910, when the national average was 55.1°. Unfortunately, the data are not available in compatible formats until after the end of the month, but the charts to the right show the temperature departures from average for March-May 1910 and for March 1-May 19 this year.
Note that for this spring to date, there have been no areas which have averaged more than 0.5° below the 1981-2010 normals. Furthermore, temperatures have been 4° or more above average over all or most of North and South Dakota, Nebraska, Kansas, Minnesota, Iowa, Missouri, Wisconsin, and Illinois.
In 1910, these extremes were primarily limited to the Dakotas, extreme northeastern Minnesota, Montana, and half of Oregon, while the southern half of Florida was more than 1° below average.
The Bottleneck Years by H.E. Taylor – Chapter 70
18 hours ago