Warmest March on record ends on sunny warm note

Sunshine and warm temperatures capped a fitting end to March 2012 as temperatures once again soared well into the upper teens Saturday. In Winnipeg the high of 18.8C Saturday was just 0.1C off the record high of 18.9C for the 31st, set back in 1963. The balmy finish however propelled the monthly mean temperature in Winnipeg to +2.2C, easily the warmest March on record in the city since records began in 1872. The month was a whopping 8.3C above normal (30 year normal = -6.1C) and 0.6C above the previous warmest March of +1.6C set back over 130 years ago in 1878.

Top 5 warmest Marches in Winnipeg (since 1872)

1. 2012 .......... +2.2C
2. 1878 .......... +1.6C
3. 1910 .......... +1.0C
4. 1973 .......... +0.5C
5. 2000 .......... -0.1C

Normal .......... -6.1C (1971-2000 normal) 
 
A historic 12 day March heat wave through mid month was responsible for the record breaking month, which helped set all time March records throughout southern Manitoba and a wide swath of central North America into the Great Lakes. The heat wave obliterated Winnipeg's 25 cm snowpack in just a few days between the 10th and 14th, with temperatures more typical of early May between the 11th and 23rd. The month set 8 new daily record highs in Winnipeg, including all time warmest March temperature of 23.7C on the 19th. The warm spell also helped kick start the growing season by a full 3-4 weeks.. a concern for plant growers worried about a return to more typical freezing temperatures in April and May.

A look at past history shows that their concerns are indeed warranted as a warm March does not necessarily translate into a warm spring. In fact, of the past 9 previous warmest Marches in Winnipeg, only 4 were followed by above normal temperatures in April, and ALL had below normal temperatures in May! Those springs had an average of 20 freeze days in April, and 9 in May with frosts well into mid to late May (even the first week of June some years!). And if history is our guide, don't put away the snow shovels just yet. Of those past 9 warm Marches, all were followed by some measurable snow in April (including a 25 cm snowstorm April 15-17, 1910), and 4 had snow in May. So don't let the warm start to spring fool you.. this is southern Manitoba after all, and a warm March is no guarantee that cold weather is over.

Some seasonably chilly weather.. then more rain for Monday afternoon into Tuesday

It may have come as a shock to residents of southern Manitoba, but after two weeks of record breaking warmth that saw temperatures more typical of early May, "normal" March weather felt anything but. Temperatures today struggled near the freezing mark all day, with gusty northwest winds and overcast skies. It was the coldest afternoon temperature in Winnipeg since March 9th which had a high of -4C. For tonight, cloudy to partly clear skies will allow temperatures to drop below -5C, our first subfreezing night since the 15th. Dry but cool conditions are expected to cap off the weekend Sunday, before clouds thicken again Monday ahead of the next major system that will affect southern Manitoba. This next system is expected to track across North Dakota Monday night into Tuesday, bringing some widespread rainfall across the RRV and southern Manitoba. Early estimates of rainfall are around 10-20 mm for Winnipeg Monday afternoon into Tuesday, with potentially higher amounts in some embedded thunderstorms which may accompany the system Monday night into Tuesday morning.

Cold front moving through Red River valley this morning with some rain and freezing rain..

A sharp cold front crossing southern Manitoba is bringing in much colder air this morning with temperatures dropping dropping below the freezing mark on gusty northwest winds. The front is accompanied by a band of rain that will be falling in subfreezing air, resulting in a period of freezing rain this morning as it passes through. About 5-10 mm of rain has fallen with the band with even some isolated thunderstorms occurring. The ground is warm enough from the mild temperatures of the past two weeks that significant icing should not be a major problem.. however some icing is possible on bridges and overpasses as well as sidewalks so be aware of the potential of some slippery conditions as you head out this morning. The band of rain will end by mid morning with drier air this afternoon, however temperatures will be back to normal values for this time of year.. which will be a bit of a shock after the abnormal warmth of the past two weeks. Seasonable temperatures will continue Sunday with mainly sunny skies, before milder but wet conditions move in by Tuesday.

Staying mild through Friday.. turning cooler this weekend with some rain possible

The well above normal temperatures will continue for a couple more days this week, before we get a cool down this weekend along with a chance of some showers. Temperatures are expected to climb towards the 20C mark again by Thursday, which if reached, would be the third 20C day recorded this month, matching the total number of 20C March days in the past 140 years. Increasing clouds Friday will give way to a chance of showers Saturday as a cold front pushes through, with cooler conditions in the single digits for Sunday. In fact, temperatures will only be dropping to normal values for this time of year.. but then, you'll have to forgive people if they've forgotten what normal is over the past couple of weeks. Temperatures are expected to be back above normal values for the last week of March, which will likely head into the record books as the warmest March on record in Winnipeg since records began in 1872.

UPDATE: Thu March 22: A record high of 21.7C was recorded today at Winnipeg airport, breaking the day's previous record high of 18.3C from 1878. It was the city's 8th record high in the past 12 days, and the third day this month of at least 20C.. equalling the total number of 20C days recorded in Winnipeg in March in the past 140 years. Note also that all 20C days this month occurred earlier than any previous 20C readings.

20C days in March - Winnipeg (since 1872)

1. 23.7C ..... Mar 19 2012

2. 23.3C ..... Mar 27 1946

3. 22.8C ..... Mar 23 1910

4. 21.7C ..... Mar 22 2012

5. 20.9C ..... Mar 18 2012

6. 20.6C ..... Mar 28 1938
* 19.9C ..... Mar 16 2012

* Note: Winnipeg had a high of 19.9C on Mar 16th this month, narrowly missing another official 20C day by 0.1C. For all intents and purposes however, one could consider that another 20C day, in which case it can be argued that Winnipeg had more 20C days this month than in the past 140 Marches combined. (note that before Canada went metric, temperatures were measured in deg F, which were converted to metric equivalents in 1975. A temperature of 19.9C before 1975 would have been recorded as 68F, which would have been converted to 20.0C when we went metric)

Thunderstorms mark fitting end to warmest March day on record..

Golf courses in full swing in
Winnipeg - March 18 2012
(Winnipeg Free Press photo)

The earliest thunderstorm on record in Winnipeg (since 1953) marked a fitting end to a summerlike final day of winter over the Red River valley.. as record breaking temperatures soared into the 20s along with gusty southerly winds and summer like humidity. In Winnipeg, the temperature peaked at 23.7C Monday afternoon, the warmest March day in the city since records began 140 years ago in 1872. The reading beats the previous warmest March day of 23.3C set over 65 years ago on March 27 1946. It was also Winnipeg's 5th consecutive daily record high, and the 7th in the past 9 days since this historic warm spell began on March 11th. The day also established a new record high minimum temperature for March, with a low of +13.3C at YWG airport.. the only time on record with a March low temperature in the double digits (previous warmest low was +7.8C on March 25 1945.)  In addition, the day featured summerlike humidity with dewpoints of 16C much of the afternoon, with a peak HUMIDEX reading of 28C at 3 pm in  the afternoon. These likely represent the highest such values ever recorded in March in Winnipeg.

List of record highs in Winnipeg : Mar 11 - 22, 2012

Date... REC HIGH (year) - Winnipeg Airport (data since 1872)

Sun 11 ..... 12.8C (2012) (prev 12.5C 1981)
Mon 12 ..... 9.7C (2012) (prev 7.2C 1922)
Tue 13 ..... 12.2C (1902) (11.7C 2012)
Wed 14 .... 11.4C (1981) (10.2C 2012)
Thu 15 ..... 14.4C (2012) (prev 11.1C 1927)
Fri 16 ...... 19.9C (2012) (prev 12.4C 1981)
Sat 17 ...... 19.2C (2012) (prev 12.8C 1938)
Sun 18 ..... 20.9C (2012) (prev 14.4C 1910) *earliest 20C reading on record*
Mon 19 .... 23.7C (2012) (prev 18.9C 1938) *new all time March maximum*
Thu 22 .... 21.7C (2012) (prev 18.3C 1878)

Temperature graph from my
weather station in Charleswood
March 19 2012

This warm spell has been one for the record books. Between March 11th-22nd, Winnipeg set 8 new record highs, including 3 days above 20C. In the previous 140 years of records, the 20C mark has been reached on only 3 occasions in March in Winnipeg (once each in 1910, 1938 and 1946). In other words, it took only 5 days during this warm spell to match what took 140 years to accomplish. Truly extraordinary. The warm spell has shattered records for March warmth throughout southern MB, the US plains, Great Lakes and eastern North America both in terms of extremes and duration. See blog entries from Jeff Masters, Chris Burt and A Weather Moment for more insight into this memorable weather event.