At 9:30 pm on October 12th the temperature went down to -0.2 °C marking the end of the frost-free season. This is pretty much the average data of first frost in the last 10 years. Note that on the evening of October 7th the weather station run by Environment Canada at the Waterloo-Wellington airport first went below zero, but the UW weather station didn't quite get that low.
The start of the frost-free season was on May 1 of this year, making the length of the season a total of 165 days. This is about a week longer than the average frost-free season in the last 10 years.