Ontario Weather Review - August 2005
What a difference a year makes. Over the course of June, July and August, most locations broke seasonal record temperatures, many of which had stood for 50 years. The number of days reaching 30 degrees this summer throughout the province exceeded those of 2004 by a wide margin. Windsor, the warmest city in Ontario, had 45 days when the mercury climbed over the 30-degree mark, but this was still shy of the record 52 days in 1988. North Bay was the only centre to break the 30-degree days record total this year, with 15 days exceeding the mark. The previous record was 12 days in 1988.
Individually, the month of August began where July left off. Thirty-degree weather continued into the first week of August in many centres across Ontario. Midway through the second week, a cooler weather pattern took hold. While overall monthly temperatures were roughly two degrees above normal for most locations across the province, no records were broken for the month.
Many areas in southern Ontario recovered from previous dry conditions as the August rainfall numbers edged up to near normal levels. Drier conditions prevailed throughout much of the north, with a number of locations received only 30 per cent of normal amounts for the month. Even in the south, dry conditions continued into August in areas unaffected by passing thunderstorms.
Severe Weather
Four more tornadoes were added to this season's total in August. The first occurred on August 10 in the Saintfield area (north of Port Perry) and was rated as a Fujita Scale zero tornado (winds approximately 100 kilometres per hour).
Three more tornadoes occurred on August 19, with two of them related to one significant thunderstorm cell. The first tornado from this cell moved through the Milverton to Conestogo Lake area, northwest of Kitchener, and the second tracked from the Salem-Fergus area to Lake Belwood (north of Guelph). Both of these tornadoes were rated as Fujita Scale 2, with winds between 180 and 240 kilometres per hour.
Recent evidence brought to the attention of Environment Canada indicated the possibility of a third tornado occurring on August 19. An Environment Canada team has now confirmed that a Fujita Scale 1 tornado, with winds of approximately 120 to 150 kilometres per hour, occurred in the Tavistock area to the southeast of Stratford. This now brings this season's total number of tornadoes to 11. The average number of tornadoes in Ontario each year is 14.
The same thunderstorm cell that spawned the two Fujita Scale 2 tornadoes then proceeded to move through the Brampton area, the northern boundary of the City of Toronto and portions of Vaughan and Markham. Local amounts in excess of 100 millimetres fell in a little over an hour, causing some flooding and damage to roads.
The remnants of hurricane Katrina brought a wet end to the month for locations along the lower Great Lakes. After causing significant destruction to the United States Gulf Coast area, what was left of Katrina brought a drenching rain to portions of Southern Ontario. The Niagara Peninsula and the St. Lawrence River Valley, from Kingston to Cornwall, experienced the greatest impact from this event, with amounts in the 50- to 75-millimetre range and locally as high as 100 millimetres.
Unusual high temperature readings:
| Location | Mean Temp. | Normal | Difference | Warmest Since |
|---|
| Kingston | 22.2 | 19.5 | +2.7 | 2001 |
| Wawa | 17.5 | 14.9 | +2.6 | 1983 |
| Toronto Pearson | 22.5 | 19.9 | +2.6 | 2003 |
| North Bay | 19.7 | 17.3 | +2.4 | 2001 |
| Petawawa | 20.0 | 17.6 | +2.4 | 2003 |
| Windsor | 23.9 | 21.6 | +2.3 | 1995 |
| Timmins | 17.8 | 15.7 | +2.1 | 1973 |
| Kapuskasing | 17.7 | 15.7 | +2.0 | 1995 |
| Muskoka | 19.5 | 17.5 | +2.0 | 2001 |
Unusual low precipitation readings (in millimetres):
| Location | Precip. | Normal | Difference | Driest since |
|---|
| Timmins | 29.1 | 82 | -52.9 | 1976 |
| Thunder Bay | 41.5 | 87.5 | -46 | 1997 |
| Wawa | 57 | 99.5 | -42.5 | 2002 |
| Dryden | 46.5 | 84.8 | -38.3 | 1997 |
| Geraldton | 48.2 | 82.9 | -34.7 | 1999 |
| Sioux Lookout | 56.7 | 88.5 | -31.8 | 2001 |
| Windsor | 50.2 | 79.7 | -29.5 | 2002 |
| Kapuskasing | 54.1 | 80.3 | -26.2 | 1999 |
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