Environment Canada

Environment Canada

May 31, 2005 11:15 ET

Environment Canada: Ontario Weather Review

TORONTO, ONTARIO--(CCNMatthews - May 31, 2005) - May 2005 turned out to be a record-setting month in Ontario, weatherwise, not for what it had but for what it didn't have: Precipitation.

Five locations across the province experienced their driest May on record. Another 13 sites had notably arid conditions, including one - downtown Toronto - which hadn't had this little rain in the month since 1934.

The entire province would also have ended up well below normal for precipitation except for an unusual storm event in Northwestern Ontario. On May 25 and 26, a heavy rainfall event moved through the Fort Frances-Rainy Lake and Dryden-Ignace areas of Northwestern Ontario, dumping in some cases more than 50 millimetres of rain over the two-day event. These were measured totals; radar estimates of precipitation indicated that locations just to the south of Dryden received rainfall in the range of 75-100 millimetres. In some cases, this event doubled the rainfall normally received in these areas for the entire month of May.

May was also a cold month, with temperatures right across the province one to three degrees Celsius below normal.

The cooler conditions, in turn, may be credited with delaying the start of the summer severe weather season. In most locations in Southern Ontario and Eastern Ontario, conditions haven't been this cold since 2002.

Severe Weather for May

May 31 represents the 20th anniversary of a devastating series of tornadoes that swept through Southern Ontario in 1985. The tornadoes left 12 dead, hundreds injured and hundreds of millions of dollars in damage in their wake. The most damaging tornadoes occurred in Barrie, where eight people died, and in the Grand Valley-Tottenham area, where four people were killed.

This anniversary occurs during a May that is notable by its relative lack of damaging storms. In fact, the spring of 2005 represents one of the slowest starts to the summer severe weather season in Ontario in recent memory. Southern Ontario usually reports the first damaging spring storms, but this year most of the activity has occurred in Northwestern Ontario.

Also of note was the report of two probable rapidly swirling winds known as dust devils: one on May 18 in the Holland Landing area, north of Toronto, and the second on May 25 in the Sudbury area. In both cases, it was reported that minor damage was caused by the winds. Dust devils can occur on very warm and dry days over sandy soils or paved areas. They are usually very small, dissipate quickly and do little or no damage. However, some can be tens of metres across and have winds approaching 100 kilometres per hour.

Other notable severe weather events of this past month included:

- May 5: a damaging hail event in the Lake of the Woods area;

- May 13: strong, gusty winds from a thunderstorm or a possible Fujita Scale 0 tornado (winds up to 118 kilometres per hour) occurred in the Rodney area to the southwest of London. Some tree damage was reported with this event. Environment Canada continues to investigate this event to confirm whether a tornado was responsible for the damage.



Statistics

Record low precipitation (in millimetres):

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Location Precip. Normal Difference Previous Record (Year)
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Kingston 16.0 75.1 -59.1 29.5 (1966)
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Sudbury 20.6 77.5 -56.9 22.1 (1977)
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Peterborough 20.0 73.2 -53.2 26.9 (1980)
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Waterloo 27.0 78.3 -51.3 32.3 (1971)
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Elliot Lake 32.0 77.5 -45.5 49.4 (1996)
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Unusual low precipitation readings (in millimetres):

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Location Precip. Normal Difference Driest since
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Toronto (downtown) 14.8 73.3 -58.5 1934
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Toronto (Pearson) 14.4 72.5 -58.1 1962
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North Bay 30.3 87.6 -57.3 1982
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Wiarton 18.0 75.3 -57.3 1951
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Muskoka 34.0 91.1 -57.1 1977
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Trenton 22.2 71.6 -49.4 1987
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Windsor 33.0 80.8 -47.8 1988
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Hamilton 39.4 75.6 -36.2 1998
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Chapleau 37.0 72.7 -35.7 1998
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Earlton 34.0 67.0 -33.0 1992
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London 50.0 82.9 -32.9 1998
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Ottawa 48.0 79.0 -31.0 1999
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Timmins 40.0 69.2 -29.2 1982
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Unusual high precipitation readings (in millimetres):

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Location Precip. Normal Difference Wettest since
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Thunder Bay 120.0 66.5 +53.5 1970
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Sioux Lookout 116.5 64.4 +52.1 2004
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Dryden 115.0 67.2 +47.8 2004
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Red Lake 93.6 54.6 +39.0 2002
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Unusual mean temperature readings:

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Location Mean Temp. Normal Difference Coldest since
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Peterborough 9.4 12.4 -3.0 1997
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Waterloo 9.9 12.5 -2.6 2002
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Ottawa 11.1 13.4 -2.3 2002
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Muskoka 9.4 11.5 -2.1 2002
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Kenora 9.7 11.8 -2.1 2004
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Hamilton 10.9 12.9 -2.0 2002
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(Egalement offert en francais)


Contact Information

  • Environment Canada, Ontario Region
    Jack Saunders
    Communications Advisor/Media Relations
    (416) 739-4785
    http://www.ec.gc.ca