Wednesday, September 30, 2009

Spectacular September salvages sorry summer - September 2009 warmest on record

After subjecting southern MB to 9 months of below normal temperatures, Mother Nature relented in dramatic fashion by delivering the warmest September on record across much of the southern Prairies. In Winnipeg, the month finished with an average temperature of 17.7C at YWG airport, over 5 degrees above the normal 12.3C and the warmest September in Winnipeg since records began in 1872. The month was nearly a full degree warmer than the previous warmest September of 1948 at 16.8C. In fact, September 2009 had a monthly mean of 19.0C through the 26th, before 4 days of cool weather at the end of the month shaved over a degree off the final average.

September 2009 was a summer-like month with plenty of sunny warm days, and only 4 days with measurable rain. The stretch between the 13th and 25th was especially nice, dominated by sunshine and 25-30C temperatures that was interrupted only one day with cloudy skies and a brief shower over the two week period. The month finished with an average temperature higher than any month of the year, the first and only time in Winnipeg’s climate history that September was the warmest month of the year. Every day from the 1st to the 27th was above normal with 19 of those days reaching a temperature of 25C or higher, the most 25C days of any September (previous record 16 days in 1940) and nearly twice as many as July had (10 days) Amazingly, no daily record highs were established during the month, highlighting the fact that it was the persistence of the warm weather that was the story, rather than any extreme heat. This was evident with the night-time lows, with no lows below 10C until the 22nd. A cool snap at the end of the month produced the season’s first frost on the 29th with a low of -2.4C at Winnipeg airport. Downtown however remained frost free all month.

Precipitation at the airport totaled 22 mm, less than half the average September monthly precipitation of 58 mm. Of the 22mm total, only 1 mm fell after the 11th. The sunny dry warm weather was a blessing for area farmers who needed an extended period of warm dry weather to make up for a slow growing season delayed by cool temperatures and rainfall. As a result, many crops were able to mature before the late frost, and be harvested in fine sunny conditions. The weather was also a boon to local beaches and golf courses, making up for some lost ground from a cool wet summer.

Overall, a September to remember! (see NCDC September summary for more info)


  1. Rob!

    Thanks for putting in all the effort in getting all those stats and information!!!!

    Lots of work there!

  2. Kudos Rob on a great Summary and an outstanding month (your coverage).

    How long will we be just spectators to that line of cloudy and windy weather southeast to MplsFargo and the Northwest to Regina?

  3. Here in South St-Vital, I surprisingly measured about 60mm of rain this September, mainly due to heavy rain on the 11th that brought about 40mm. Just surprised how much more than the airport!

    Anyways, thank you for the monthly summaries Rob.

  4. Thanks Jewels..

    Yeah, the south end of the city got more rain than the north end in September, as it did in August as well! I measured about 35 mm in Charleswood for September, about halfway between the airport and St Vital. The northwest part of the city, where the airport is located, missed most of the heavier rainstorms in August and September.

    Some parts of southern Winnipeg got 135 mm of rain in August, while the airport only got 56 mm for the month. Just goes to show you how variable precipitation can be in the summer, even within the same city!

  5. Here in Silver Heights, I got 41mm of pcpn in September and I am only 3km from the CYWG observing site! (nearly double what CYWG reported)
    Like the rest of you, most of my rain was recorded on the 8th (16.0mm) and the 11th (19.4mm).

  6. Despite of the warm September in 2009, due to dominance of rain over July and August, many kids missed water parks like in Portage or Fun Mountain.

    Fun Mountain previously closes after Labour Day weekend but since 2006, they close in late August due to some schools open before the long weekend, though most of our schools open after that.

    At Splash Island in Portage la Prairie, it closes after Labour Day weekend.

    All of two water parks were closed due to plenty of rain over July and August.

  7. Rob, in September 2009 none of severe weather occurred in Winnipeg. But rain and thunder happened on the morning of the day after Labour Day. In 1981, 2007 and 2008, thunderstorms have occurred in Winnipeg when we officially enter the season of fall.

    Had thunderstorm struck Winnipeg at the end of September or beginning of October in the past?

    When I read the weather forecast by AccuWeather on a Free Press back in 2007, forecast for Tuesday, October 2nd 2007, thunderstorm might hit Winnipeg with a high of 17.

    In the Philippines, this type of weather is different than SoMan (Southern Manitoba). There, thunder isn't seasonal due to tropical climate as thunderstorms may occur anytime in the year but frequent during monsoon season, which lasts from May to November down in the Philippines, where I lived most of my childhood from the 1990s to the early 2000s.