Mono Lake’s record-breaking summer of warm temperaturesSeptember 21st, 2012 by Greg, Information & Restoration Specialist
The summer of 2012 was hot. But how hot? As we celebrate the Autumnal Equinox and the end of summer, let’s take a look back and see how the weather this year (so far) compared to previous years. Our focus is on temperatures—every month this year has had above-average temperatures. In October, we will summarize the meager precipitation and snowfall that fell during the dry October 1, 2011–September 30, 2012 Water Year.
The year started out very dry, continuing a pattern from the end of last year that kept the Sierra snow-free and Tioga Pass open until January 17th (a new record). Lee Vining’s highest temperature in January of 61° F (reached twice) was only exceeded in January 1990 (in records that go back to May 1988)—but 48.6° F set a new January record for the average daily maximum temperature. The average daily minimum temperature was the fourth-highest on record. The lowest minimum of 12° F was the warmest on record—tied with five other Januaries!
February 2012 also had a maximum temperature—60° F—that was only exceeded once—66° F, in February 2002. The average daily maximum temperature of 46.3° F was the fourth-highest on record for February. The average daily minimum was slightly below average—and it was the only month so far this year that wasn’t above average.
March’s maximum temperature was the sixth-highest on record. The average daily maximum was slightly below average—it was the only month so far this year that wasn’t at least 2° above average.
A new record was set for April: 38.7° F was the warmest average daily minimum for that month, beating the 1989 record by over 2°. It was almost two standard deviations above the mean of 32.3° F.
July’s average maximum was the fourth-warmest on record. If not for one day that dipped to 48° F, the lowest July minimum would have been 50° F and would have been the second warmest on record after 51° F in July 2006.
August’s average maximum of 86.7° F set a new record, but it barely beat August 2008. The average daily temperature of 70.7° F also set a new August record.
Summer 2012 (defined here as June-July-August) was the warmest summer since 2007. There were ten days in the 90s, and five nights with lows in the 60s. In 2007 there were 12 days in the 90s (matched in 1994 and exceeded only by 14 days in 2002). 2007 was the record setting year for number of nights in the 60s, with 10 (followed by 9 in 2003, and 7 in both 2005 and 2006). On average there are less than five days in the 90s and less than four nights in the 60s.
This year was also the driest year since 2007. More details on that in October…