Sunday, January 27, 2013

A history of weather observing in Winnipeg

It's a question that people ask routinely.. what is the temperature outside? And although you can get a reasonable answer from a variety of sources these days from car thermometers to billboard displays, the official answer always defaults to the temperature reading at Winnipeg airport's weather station, the official source of weather observations for Environment Canada. Weather observations started at Winnipeg airport (YWG) in March 1938, and have been a daily ritual for the past 75 years, measuring all aspects of Winnipeg weather including temperature, precipitation, wind, pressure, humidity, and virtually anything else that Mother Nature has thrown us.

As we approach the 75th anniversary of weather observations at Winnipeg airport, let's take a retrospective look at the history of weather observing in Winnipeg.

Winnipeg's first official weather observations: St John's College (1872 - 1938) 

St Johns College
Site of weather observing
program for Winnipeg
1872 - 1932
Official weather observations in Winnipeg actually began many years before Winnipeg airport was even around. In 1871, the Canadian federal government established the Meteorological Service of Canada, mainly as a warning service for mariners. To help forecast the weather, the department established weather stations across the country to report on local weather conditions. One of these early sites was in Winnipeg, first manned by James Stewart, who started preliminary observations around 1870, likely near Main St and St Mary Ave where he operated a drug store (across from the former Grace Church).

See November 1872 newspaper article mentioning appointment of James Stewart as official weather observer for the Winnipeg meteorological station. (last paragraph) 

Winnipeg in the 1870s
Main St and Bannatyne
The image left shows what Winnipeg was like in the 1870s when Stewart started recording weather data for Winnipeg. This was Main St just up the road from where Stewart had his pharmacy (and most likely where he started taking weather observations). Although it appears that Stewart took daily weather readings beginning in 1870, continuous archived data is not available until March 1872 when official weather records began for Winnipeg By 1874, the weather station was moved to a more permanent location at St John's College (top image), about 2 miles north of Portage and Main, on Main St between Church Street and Anderson, site of the present day MPI building. (See 1911 city map below showing location of St John's College)

An August 1874 newspaper article details news of upgrades to St John's College including upgrades to the meteorological observatory. The article mentions the addition of a self-registering anemometer on a newly built tower at the College, which suggests that more detailed wind data for Winnipeg (including peak gusts) was available from the St John's College site as early as 1874.  If you look closely at the photo of St John's College above, there appears to be an anemometer tower mounted on top of the left side tower of the college.
1911 Winnipeg city map showing location of
St John's College off Main Street (north is to the right) 

Manitoba Agricultural College
U of M, Fort Garry
Weather observations were
taken here from 1932 - 1938 
Daily weather observations would continue uninterrupted at the downtown St John's College site for 57 years until April 1 1932 when the station was moved to the Manitoba Agricultural College at the University of Manitoba campus in the south end of the city (Fort Garry). Readings would continue at the university site (still considered part of the St John's climate record) until the newly formed Winnipeg airport took over weather observing duties in 1938. The observations from St John's College are recognized as official climate records for Winnipeg, and are included in a merged climate database with Winnipeg airport that extends the city's weather record database to over 140 years, one of the longest continuous weather observing programs in Canada. St John's College climate database holds the distinction of having both the hottest and coldest temperatures ever officially recorded in Winnipeg... 42.2C (108F) on July 11 1936, and -47.8C (-54F) on Dec 24 1879. In addition to temperature and precipitation data, St John's College also recorded data on thunderstorms, sunshine, and winds as early as the 1870s. Unfortunately, this data has not been digitally processed and is not available in the online Canadian climate archives. (Click here for historical weather data at St Johns' College between 1872 and 1938.)

Winnipeg airport observations : March 1938 - present

Winnipeg Intl Airport ca 1950s
known as Stevenson Aerodrome
before it eventually became
Richardson Intl Airport (YWG)
In March 1938, Winnipeg International airport (known as Stevenson Aerodrome at the time) began its official weather observing program to support aviation and meteorological services. The observing program relied on human weather observers to record daily weather data, including extremes. In January 1947, a full hourly observing program began at the airport, with hourly weather data available online from January 1953 on.  On December 1 1963, the weather station was relocated on the grounds of the newly constructed Winnipeg International Airport (later replaced by the new Winnipeg Richardson Airport in 2011). The human based observing program at the airport continued uninterrupted for 70 years until July 2008 when automation starting taking over weather observing commitments. This marked an important transition in the weather observing program that had been a strictly human based endeavour for over 135 years. (Click here for Winnipeg International airport observations between 1938 and 2008)  

Observing note: In September 1938, the wind anemometer at the Winnipeg airport was mounted on top of a hangar at a height of 20 metres (63 feet), twice the height of the internationally accepted standard of 10 m (33 feet) As a result, wind speeds from the Stevenson airport were somewhat higher than official standards from 1938 until Dec 1 1963, when the anemometer was lowered to the official 10 metre height at the new airport location.

Weather observing program moves towards automation: July 2008 - present

In July 2008, weather observations for YWG airport switched to an automated system as modern technology and tightening resources necessitated a change in the human observing program. Most of the weather data is now collected automatically from an Automated Weather Observing System, or AWOS for short. A human observer still inputs the data manually including precipitation start and end times, but for the most part, much of the weather observation is taken automatically by the AWOS. An important note here is that snowfall data (including snow depth) stopped in 2008 since AWOS is not able to measure snowfall depth, and human observers were not required to take snowfall measurements manually.  Instead, the AWOS measures only melted snow , ie. the water equivalent of snow that falls. Thus, snowfall data for Winnipeg, which had been taken since 1872, was no longer being observed after 135 years of continuous observations. Snowfall data for Winnipeg is now taken at nearby volunteer climate stations that still record snowfall manually, including my site known as Winnipeg Charleswood 2.

January 2013 - A change in automation and station ownership

On January 17 2013, the automated weather observations from YWG were switched to a new AWOS station operated by NavCanada, the agency responsible for aviation services in Canada. This signalled the first time that weather observations for Winnipeg airport were not the responsibility of the Meteorological Service of Canada, but a third party. This new weather observation station, known as an HWOS (Human Weather Observation System) relies on automated observations from the weather station, but still requires a human observer to input the observation (like the previous AWOS setup)   Environment Canada still has a co-located weather station at the airport (Winnipeg A CS - XWG) although hourly weather information for Winnipeg (as displayed on Weatheroffice's "current conditions" city page) comes from the HWOS station. Note that only hourly data is available from this station, not daily or monthly climate statistics (this station is listed as "Winnipeg" on EC's climate website). As of Oct 2013, all official daily highs, lows and precip data for Winnipeg airport are from the Winnipeg A CS site (XWG station) which is operated by Environment Canada.

In summary, here are the list of official Winnipeg observing stations: 

St John's College ...... March 1872 - July 1938 (daily & monthly data)
 - includes data from Manitoba Agricultural College site 1932-1938
Winnipeg Intl A ..........  March 1938 - July 2008  (hourly, daily & monthly data)
Winnipeg AWOS .......  July 2008 - Sep 2013 (hourly and daily data)
Winnipeg (HWOS) ....  Jan 17 2013 - present (hourly data only - NavCanada site)
Winnipeg "A" CS .....  Oct 1996 - present (daily data, monthly data to 2008)

NOTE: As of Oct 2013, the Winnipeg A CS site (owned and operated by Environment Canada) is the official site for daily climate data for Winnipeg airport. 

Other observing notes:
- Water equivalent for snowfall readings began on Nov 1 1960. Before then, water equivalent of snowfall was simply obtained by dividing the snowfall amount by 10.
- Prior to July 1 1961, the meteorological day for precipitation measurements was considered the 24 hr period from 630 am until 630 am of the following day. On July 1 1961, the meteorological day was changed to the synoptic day ending at 06 UTC for precipitation measurements.  This correlates to midnight during standard time (Nov - Mar), and 1 am during daylight savings time (Mar - Nov)   

In addition to the airport station, Environment Canada also has an automated station downtown at The Forks, which began operation in November 1999. This station has maintained the same automated observation program since inception.

Although equipment and reporting procedures have changed, Winnipeg residents can be rest assured that weather observations continue at Winnipeg airport maintaining a legacy of weather observing in this city that has spanned over 140 years.

Winnipeg weather extremes since 1872:

Hottest temperature:   42.2C  July 11 1936
Coldest temperature-47.8C  Dec 24 1879
Greatest snow in 24 hours38.1 cm  March 4 1935
Greatest rain in 24 hours:  152.4 mm  June 26 1901
Highest wind gust129 km/h  Feb 20 1965
Lowest windchill-57  Feb 1 1996
Highest humidex:   47C  Jul 25 2007          


  1. Thanks for the great information in this post.

  2. This comment has been removed by the author.

  3. Weakening band of snow pushing through Winnipeg this morning.. bulk of it is passing to the north of us, but we may see a dusting to 2 cm here in the city. Portage has picked up 2 cm this morning, Brandon 3 cm.

  4. 152 mm in one day wow! Rob would that be the month with the highest amount of precipitation, 255 mm? And is the yearly precipitation record still 723.5 mm in 1962?

  5. How can u go from a 5am update of 30% chance of flurries to a 11am update of snow 2-4cm. Does that mean tomorrows 60% chance of flurries is going to be 5-10cm.

  6. I hear you Daryl,

    This is kind of ridiculous. Being in the snow clearing business as well I do rely on a somewhat accurate forecast. Going from 30% chance of flurries to 2-4 cm out of the blue is quite strange. Hell I can look at the radar and make these forecasts.

  7. Right now, we're the only province (sans the NWT and Nunavut if one was to include those territories) without any sort of a watch or warning.

  8. I picked up around 0.5-1 cm in Charleswood today.. it was more of an off and on flurry type of day. Light fluffy stuff.. Looked worse at times than actually accumulated.

  9. >> Anonymous said.. 152 mm in one day wow! Rob would that be the month with the highest amount of precipitation, 255 mm? And is the yearly precipitation record still 723.5 mm in 1962?

    Yes, June 1901 is Winnipeg's wettest month at 255 mm thanks to that 152 mm rainfall. And 1962 is still Winnipeg's wettest year..

  10. Considering there was only 0.3 mm less precip. in 2010 compared to 1962, combined with a dry bias at the airport that we've been taking about the last few years, I wouldn't be surprised if 2010 truly is the wettest year.

    If we take rainfall only, I've calculated it to be a total of about 640 mm that year, which easily makes 2010 the rainiest year (beating 633.5 mm in 1977). If this dry bias thing is true, then that amount is even higher... Rob had 753.2 mm of rain, while amounts were even higher in south/east ends thanks to some more direct hits by tstorms.

  11. @Daryl,

    Looks like (for the most part), that change to the forecast yesterday is working out.

  12. Brad
    Not sure quite what u mean. Forecast change yesterday called for 2-4 cm yesterday and we got maybe a 1/2 cm. And 60% chance of flurries today. Forecast changed again with periods of snow for today now changed again till tomorrow noon.

  13. Very mild conditions in Southern Ontario/Southern Quebec with thunderstorms...

    Up to 17C in the Niagara peninsula.

  14. 17.2C in Port Weller, Ontario today... Canadian warmspot.

    Up to 16.1C in extreme Southern Quebec as well.

    Further south, they are having tornadoes.

  15. Hi there. The College was actually on the west side of Main Street between Church & Anderson. The Cathedral was on the east side. You can see both locations on this interactive map of Winnipeg from 1911:

  16. Canafornian..

    Thanks for the link! I've updated the blog entry to include that info. Much appreciated.