A second round of summer snow has struck Calgary, Alberta, Canada, snarling travel, downing trees, and triggering thousands of power outages.

The weight of this wet snow took its toll, downing numerous leafy trees inCalgary, the province's largest city at a population of 1 million. About 30,000 customers were without power as of Wednesday morning, according to ENMAX, the city's electricity provider.

According to the Calgary Herald, the city received over 900 reports of fallen trees and responded to 168 vehicle crashes in less than 24 hours from Monday morning through Tuesday morning. The city opened its emergency operations center Tuesday to coordinate the response.

Roads were being salted and were generally slushy, though power outages affected some traffic lights. A handful of flights were either delayed or cancelled at Calgary International Airport, according toCBC News. Air Canada issued a travel alert, waiving change fees for those scheduled to fly into or out of the airport.

Calgary International Airport reported 11.8 centimeters (about 4.6 inches) of snow Monday, another 1.3 centimeters (about 0.5 inches) Tuesday, then 15.1 centimeters (about 5.9 inches) Wednesday.

Shocking as the snow was to many, it wasn't the city's earliest late-summer snowfall. Calgary recorded 11.7 centimeters (just under 5 inches) of snow on Sept. 8 in 1921, according to Environment Canada statistics.

The earliest single-day snowfall of 10 centimeters (4 inches) or more there was on Sept. 6, 1972, but Calgary had a two-day total of 10.4 centimeters on Aug. 25-26, 1900.

It even snowed in Calgary once in July, when 0.3 centimeter (0.1 inch) fell on July 23, 1918.

September has, on average, 1-2 days of measurable snow in Calgary. On average, only one September day every three years sees at least 5 centimeters (just under 2 inches) of snow. Calgary's three-day total of 28.2 centimeters (about 11.1 inches) is on par with average snowfall for September, October and November, combined (31 centimeters), according toEnvironment Canada, the country's equivalent of the National Weather Service.

This week's snow was an attention-grabber, especially coming so early in the month and just a day after Sunday's high of 78 degrees Fahrenheit.

Some of that snow spilled over the international border, delivering over a foot of snow to the Bighorn Mountains west of Sheridan, Wyoming, and the earliest measurable snowfall on record in Rapid City, South Dakota.

(MORE: First Frost, First Snow in High Plains| Earliest First Snow of Season Where You Live)

MORE ON WEATHER.COM: Calgary's September Snow

Horse graze a snow covered pasture on a farm near Cremona, Alberta, Canada, Wednesday, Sept. 10, 2014. Environment Canada has ended a snowfall warning for Calgary, and much of the rest of southwestern Alberta. (AP Photo/The Canadian Press, Jeff McIntosh)