WET SEPTEMBER START TYPICAL FOR ENDING OF SUMMER

MUSKOKA — As predicted, September is off to a wet start.

Heavy rain overnight and again Wednesday morning is typical for this month, which typically sees the beginning of the gradual decrease in temperatures of autumn.

This year should be no exception, writes Peter Kimbell of Environment Canada.

That being said, he says the temperature anomaly forecast for the month seems to indicate near normal, with precipitation possibly above normal during the first week of the month.

That follows August when there were “storms aplenty and roaring fires” across Ontario.

He goes on ….

Temperatures and precipitation:

Relative to the extreme heat experienced in July, August temperatures ranged from normal to slightly-above-normal across Ontario.

Still, on many occasions, minimum temperatures dipped down to the low tens or even single digits.

Much of the southwest and central regions received more rain than usual resulting in anomalies ranging from +50 to +175%.

The largest anomalies were reported in Grey-Bruce region extending into central Ontario, where some areas received over double their normal precipitation amounts. Parts of northern Ontario experienced a dry August with precipitation anomalies ranging from -10 to -50%.

Observations compared to the 1981-2010 normals for August 2020 (see Appendix for a geographic representation of all of Ontario) City	Mean Temp (obs/normal) (°C)	Difference (°C)	Total Precip (obs/normal) (mm)
Kenora	19.7 / 18.6	1.1	91.5 / 84.2
Moosonee	15.2 / 14.9	0.3	75.2 / 77.8
OttawaAirport	19.5 / 19.8	-0.3	135.0 / 85.5
Sudbury	18.3 / 18.0	0.3	81.3 / 85.4
Thunder Bay1	17.1 / 16.6	0.5	93.7 / 87.5
Toronto Pearson	22.1 / 20.6	1.5	91.0 / 78.1
Windsor	21.9* / 22.0	-0.1	228.9* / 72.6

 *estimated or incomplete value

1 1971-2000 normals used

Significant events

August 2: Rain in South-Central Ontario; Tornadoes in Eastern Ontario

As a low pressure system tracked northeastward across southern Ontario, significant rainfalls were reported just to the north of the track of the low.

While many areas received 40 to 60 mm of rain (Beatrice 42 mm, London 60 mm, Mount Forest 60 mm), a few received notably higher amounts (e.g. Barrie 82 mm) and a couple volunteer reports were in excess of 100 mm (Woodford, Appin).

Meanwhile across eastern Ontario, a series of strong thunderstorms prompted tornado warnings and subsequent confirmation of three tornadoes (Camden East, EF-0; Oxford Mills, EF-0; and Kinmount, EF-2). None of the three caused any injuries, but rather mostly tree damage and localized property damage.

August 4: Heavy rain and strong winds in the Hamilton area

As the remnants of Tropical Storm Isaias crossed into southern Quebec, another day of severe weather occurred in southern Ontario. A tornado report was received from Palmerston in the late afternoon, and as the parent thunderstorm moved eastwards towards the Greater Toronto Area (GTA), tornado watches and warnings pushed eastward as well.

As the line of thunderstorms crossed the Hamilton-Burlington area, during the early evening hours, reports were received of damaging winds and torrential rain causing localized flooding, in addition to a few funnel cloud reports.

August 9: Thunderstorms over Southwestern Ontario

An east to west line of thunderstorms developed over South Huron County in the early hours, from just south of Goderich to near Stratford, and then gradually moved southward towards Lake Erie during the remaining morning hours.

While Goderich only reported 30 mm, much higher rainfall amounts of up to 100 mm were reported via social media near Bayfield, 20 km south of Goderich. Many farmers’ fields were flooded.

August 9-14: Fires over Northwestern Ontario

Forest fire emergencies were in effect for two communities in northwestern Ontario: Red Lake and Fort Hope (Eabametoong First Nation, 325 km north of Thunder Bay). In the case of the Red Lake fire, the municipality made a formal declaration of emergency due to the proximity of the forest fire (5 km away), necessitating evacuations.

In the case of Fort Hope, smoke from a forest fire 50 km away was causing concern for many in the community. By mid-week, as a result of a change in wind direction and fire-fighting efforts, smoke ceased to be a major concern for Fort Hope, and by the end of the week, rainfall ended the emergency over Red Lake.

August 14-15: Rain over Northwestern Ontario

A low pressure system approaching northwestern Ontario from the US Dakotas brought significant (and welcome) rainfall to the dry areas of northwestern Ontario. Red Lake reported a two-day total of 57 mm, while Kenora reported 38 mm.

August 16: Thunderstorms over Southwestern Ontario

Thunderstorms that originated over central Michigan during the evening of August 15 became more intense as they rolled across Lake Huron overnight and dumped local amounts up to 75 mm near Kincardine and even up to 100 mm in Owen Sound. Local reports of flooding were received in communities along Lake Huron.

August 17: Thunderstorms in Eastern Ontario

Another day of scattered thunderstorms across southern and eastern Ontario. On this day, hail and gusty winds seems to have been the biggest threat. Dime size hail was reported in a number of locations, including the Greater Toronto Area (GTA), Hamilton, Petawawa and Ottawa.

Tornado warnings were issued in the National Capital Region, however none were reported. Tree damage was nevertheless reported in some Ottawa suburbs, notably Kanata.

August 26-27: Stormy across Southern and Central Ontario

As a warm front pushed gradually northeastward across southern Ontario, thunderstorms developed along the front Wednesday night from Sault Ste. Marie southeastward across Manitoulin Island and towards the Peterborough area of eastern Ontario.

Significant rainfall amounts were reported in some areas, such as 81 mm in Gore Bay, 79 mm in Tobermory and 50 mm in Wiarton, with local flooding reported in these areas. Later in the afternoon of August 27, a line of thunderstorms crossed southern Lake Huron and southwestern Ontario and triggered a couple tornadoes: Mount Carmel, (Huron County, EF-1), and Union (Elgin County, EF-1).

Minimal damage was reported (a couple of barns).

August 28: Thunderstorms for Southwestern Ontario

During the early morning hours, a series of thunderstorms rolled across Michigan into Essex County. By 8 AM, rainfall amounts of 50 to 75 mm were reported near Windsor, with a maximum of 80 mm reported at the Windsor airport.

Then, subsequent waves of thunderstorms continued during the afternoon, evening and overnight hours over Essex and Chatham-Kent counties as well as further north over Grey-Bruce, Dufferin and Simcoe counties, even eastwards as far as Peterborough.

Total rainfall amounts over a 30-hr period were close to 135 mm in Windsor, 73 mm in Durham, and 46 mm in Peterborough.

In the late evening hours (near 10:15 PM), one thunderstorm came ashore near Point Clark, in Huron-Kinloss township, and triggered an EF-0 tornado which caused damage to several residences. No serious injuries were reported.