The Historic March Heat Wave

Coming on the heels of Detroit's 5th warmest winter on record, the 12th warmest autumn, and a summer which featured July as the hottest month ever recorded in Detroit, March 2012 will likely go down as the warmest March on record. In fact, the warm spell which occurred during the middle of the month is perhaps the most anomalous weather event in Michigan since climate records began 130 years ago. The culprit was a summer-like upper level ridge anchored over the Great Lakes and Eastern US. This essentially was a dome of warm air which took up residence across the region. Strong high pressure over the eastern seaboard also led to several days of southerly winds across the region, which really helped the warm air surge from the deep south into the Great Lakes. Not only did the the region experience over a weak of high temperatures over 70, three to four days had highs over 80. This unually warm weather actually lifted into the northern parts of the state as well. Many locations in northern Michigan, including Traverse City, had several days break 80. Daily record high max temperatures were being broken all across the state and not just by a couple degrees, but in some cases they were broken by 10 to 30 degrees.

This unprecented warm spell has caused the plant life to bloom prematurely. By March 24th, the trees and shrubs were a good 4 to 5 weeks ahead of schedule. This is not necessarily a good thing though as the region has now been set up for a potentially damaging hard freeze. Because of this, the NWS Detroit/Pontiac will begin issuing frost advisories and freeze warnings. The average last freeze for most locations in Southeast Michigan is not until late April. Over 90% of Aprils in Southeast Michigan have a hard freeze (temperatures of 28 degrees or lower) sometime during the month.

So how unprecedented was this warm spell? One has to go all the way into the month of April to find a stretch of warmth that compares:

# of consecutive 70 degree days	Dates	Year
10 days	March 14-March 23	2012
9 days	April 16-24	1886

In other words, one has to go back over 125 years to find an early-season warm spell that compares, and even that streak occurred in April, a full month later. Needless to say, this stretch of 10 consecutive 70 degree days represents a new March record for Detroit, Flint, and Saginaw. With much cooler temperatures expected this week, no additional 70 degree temperatures are forecast, bringing the streak of consecutive 70 degree days to an end.

In addition to a record setting string of 70 degree days, the string of consecutive and total 80 degree days has been broken for the month of March. Detroit hit 86 degrees on Thursday March 22nd...which was the 3rd consecutive 80 degree day and 3rd consecutive day that the All-Time High for the month of March had been broken. This string of 80 degree days broke the previous record of 2 consecutive 80 degree days set back in 2007 and broke the record for the most number of 80 degree days during the month of March which was 2 also set in 2007. In Flint, the string was extended to 4 consecutive 80 degree days on Thursday. There has never been more than one 80 degree day in March in Flint's history, which occured in 2000 and 1938. In Saginaw, the string of 80 degree days ended on Wednesday with three consecutive 80 degree days and a total of four 80 degree days during the month of March. The only month that had more than one 80 degree day in Saginaw was back in 1910 when two non-consecutive 80 degree days were recorded.

All-Time Highs for March Broken

Site	All-Time March High	Previous Records
Detroit	86 degrees on 3/22/2012	84 degrees on 3/21/2012 and 82 degrees on 3/20/2012 and 3/28/1945
Flint	86 degrees on 3/21/2012	84 degrees on 3/20/2012 and 82 degrees on 3/22/1938
Saginaw	87 degrees on 3/21/2012	83 degrees on 3/20/2012 and 3/24/1910

Amazingly, all-time highs for April were even approached on March 21st and 22nd

Site	All-Time April High	Date
Detroit	89 degrees	4/12/1977
Flint	88 degrees	4/23 and 4/24/1925
Saginaw	89 degrees	4/29/1899

The number of consecutive and total 80 degree days during the month of March was also shattered

Site	consecutive 80 degree days	Previous Record/Year	total 80 degree days	Previous Record/Year
Detroit	3	2 - 2007	3	2 - 2007
Flint	4	1 - 2000/1938	4	1 - 2000/1938
Saginaw	3	1 - 1945/1938/1910	4	2 - 1910