The March heat wave continues to shatter longstanding records from the Upper Midwest to the Northeast, with more than 2,200 warm temperature records set during the month so far.
It's quite possible that this March heat wave will be considered an unprecedented event in the U.S. historical record, which extends back to the late 19th century, based on the margin by which records are being exceeded, the wide geographic scope of the heat wave, the duration of the event and the time of year when it is occurring.
According to the HAMweather website, 1,192 record daytime highs were set in the U.S. from March 12-18, along with 708 high minimum temperature records. This compares to just 66 coldest maximum temperature records, and only eight records for the coldest overnight low temperature.
More records are likely to be set today through the end of this week, when a cooler airmass finally moves eastward (as it does so, it may spark rounds of severe weather). This data may be missing some records set after March 15, since there have been some problems obtaining data from the National Climatic Data Center's website.
According to the CapitalClimate blog, so far this month warm weather records have been outpacing cold records by a lopsided ratio of 19-to-1. Since January 1, the ratio has been closer to 14-to-1.
In a long-term trend that has been found to be inconsistent with natural variability alone, daily record-high temperatures have recently been outpacing daily record-lows by an average of 2-to-1, and this imbalance is expected to grow as the climate continues to warm.
According to a 2009 study, if the climate were not warming, this ratio would be expected to be even. Other studies have shown that climate change increases the odds of extreme heat events.