News Release
OntarioWeather Review
May 2011
May 2011 presented Ontarians with a variety of weather conditions. For much of the province, there was no shortage of cloudy skies and precipitation in various forms. Despite the seasonal temperatures and abundant localized precipitations, the month ended with long-awaited summer-like conditions.
Mean temperatures were within normal values for May throughout most of the province, with Petawawa being slightly warmer than normal with mean temperatures two degrees celsius above expected values.
New rainfall and total precipitation records were set this month in Southern Ontario. Hamilton broke its 2004 rainfall and total precipitation records of 137.6 mm by more than 20 mm. Kingston also received its share of precipitation, surpassing its 2002 record.
Northern Ontario and the far north were drier than normal, with the exception of Red Lake, which was wetter than normal. Earlton received only one fourth of the total precipitation normally expected in the month of May. Dryden, Timmins, Pickle Lake and Sioux Lookout received only half of the rainfall and/or total precipitation amounts for the month.
Regions in southern and northwestern Ontario were wetter than normal. Locations such as Windsor and Sarnia received more than twice the normal rainfall and/or precipitation amounts for the month.
Severe Weather
Stubborn slow moving weather systems, at times even stationary for a few days, lingered over the entire province and made this month of May much calmer than usual with respect to severe weather.
Severe weather however showed itself in northwestern Ontario on May 10, 2011, when several bands of thunderstorms affected the region late in the afternoon and lasted well into the night. Hail was the main threat associated with those storms, and was accompanied by local strong wind gusts and isolated heavy downpours. There have been reports of hail, the most remarkable being quarter size hail in Dryden and walnut to ping pong size hail in Kivikoski, north of Thunder Bay. The storms remained active all night, north and west of and over Lake Superior. A line of storms associated with that same system reached the eastern shores of Lake Superior by the morning of May 11, 2011, and damaged houses, utility poles and trees in areas from Point aux Pins to St. Joseph Island. Meanwhile, a wind gust of 102 kilometres per hour was measured at the Sault Ste. Marie Airport.
On May 26, 2011, a warm front associated with a low pressure system over Indiana slowly moved through southern Ontario, bringing rain with embedded thunderstorms and heavy showers. Rainfall warnings were issued for parts of south western Ontario, with the Windsor Airport receiving 62 millimetres of rain in 24 hours. Due to the localized nature of the heavier showers and thunderstorms, some locations away from Environment Canada’s observation site may also have received similar amounts.
The month ended with a large low pressure system crossing northern Ontario from west to east, bringing with it thunderstorms with damaging winds and gusts up to 111 kilometres per hour, as reported at Geraldton Airport.
Despite only a few severe weather events in May 2011, it seems that Mother Nature is sending Ontarians hints that she is not quite asleep for the summer severe weather season, which extends from mid-April to October. Earlier this month, Environment Canada confirmed that the April 27th tornado in the Fergus area was the first tornado of the season and rated it as a Fujita scale zero, with winds up to 110 kilometres per hour.
Temperature And Precipitation Tables
| Location | Mean Temp | Normal | Difference | Warmest since |
|---|---|---|---|---|
| Petawawa | 13.9 | 11.9 | 2.0 | 2010 |
| Location | Rainfall | Normal | Difference | Previous Record |
|---|---|---|---|---|
| Hamilton | 160.4 | 75.0 | 85.4 | 2004 (137.6) |
| Location | Rainfall | Normal | Difference | Least rain since / Most rain since |
|---|---|---|---|---|
| North Bay | 51.6 | 85.5 | -33.9 | 2010 (Least rain Since) |
| Sioux Lookout | 31.4 | 59.7 | -28.3 | 1981 (Least rain Since) |
| Pickle Lake | 28.0 | 53.4 | -25.4 | 1997 (Least rain Since) |
| Windsor | 179.8 | 80.7 | 99.1 | 2004 (Most rain since) |
| Toronto Pearson | 141.0 | 72.4 | 68.6 | 2003 Most rain since |
| Red Lake | 88.9 | 49.3 | 39.6 | 2010 Most rain since |
| Location | Precipitation | Normal | Difference | Previous Record |
|---|---|---|---|---|
| Hamilton | 160.4 | 75.6 | 84.8 | 2004 (137.6) |
| Kingston | 138.7 | 74.8 | 63.9 | 2002 (133.5) |
| Location | Precipitation | Normal | Difference | Driest since / Wettest since |
|---|---|---|---|---|
| Earlton | 17.0 | 67.0 | -50.0 | 1957 (Driest since) |
| North Bay | 51.6 | 87.6 | -36.0 | 2010 (Driest since) |
| Dryden | 33.3 | 67.2 | -33.9 | 1990 (Driest since) |
| Timmins | 37.9 | 69.2 | -31.3 | 2010 (Driest since) |
| Sioux Lookout | 36.4 | 64.4 | -28.0 | 1981 (Driest since) |
| Windsor | 179.8 | 80.8 | 99.0 | 2004 (Wettest since) |
| Red Lake | 130.1 | 54.6 | 75.5 | 2010 (Wettest since) |
| Sarnia | 138.8 | 69.9 | 68.9 | 2004 (Wettest since) |
| Toronto Pearson | 141.2 | 72.5 | 68.7 | 2003 (Wettest since) |
| London | 127.1 | 82.9 | 44.2 | 2004 (Wettest since) |
| Toronto City | 116.4 | 73.3 | 43.1 | 2003 (Wettest since) |
Note: The normal period used is the 1971-2000 Climate Normals
Media: For more information, please contact:
Laurie Thibeault
Communications Officer
Environment Canada – Ontario
905-336-4711
- Date Modified: