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(source: See Environment Canada:Canadian Climate Normals 1971-2000 and Daily Data Report for Peterborough Station A Note that records for Station A are only available as of October, 2010. Prior to that, I have had to use the data from the Trent University Station on the edge of Peterborough )

From January 2010 through December 2023 116 of the 168 months (about 70%) have been warmer than the 1971 – 2000 Normal for each month. This is more than a 2:1 ratio for warmer versus cooler months. If the climate wasn’t warming, this ratio would be close to 1:1 over such a long period.

According to Environment Canada, the mean annual temperature in Peterborough for the 30 year period from 1971 to 2000 was 5.9 C. The mean annual temperatures for the past 14 years are as follows: 2010 (7.38 C), 2011 (7.24 C), 2012 (8.15 C), 2013 (6.4 C), 2014 (5.93 C), 2015 (6.35 C), 2016 (7.08 C), 2017 (6.8 C), 2018 (7.06 C), 2019 (5.79), 2020 (7.5 C), 2021 (7.6), 2022 (6.35) and 2023 (7.7). When added together and divided by 14, the mean annual temperature in Peterborough for the period from 2010 through 2023 was 6.95 C. In other words, Peterborough’s mean annual temperature for 2010-2020 was about 1 C warmer than the 1971 to 2000 mean.

The IPCC reported in October 2018 (summary here) that global warming must be limited to no more than 1.5 C. If warming exceeds this threshold, there is a strong likelihood that run-away, non-stoppable warming will result, fed by positive feedback loops like melting Arctic ice and permafrost. The bottom line is that Peterborough has already warmed to two-thirds of this maximum warming.

Temperature extremes

December 2015 showed the biggest departure (7.9 C ) from Normal (-5.3 C) for all months of December since at least 1968. In the summer of 2018, 28 days were above 30 C, according to data from Peterborough Trent U weather station. In 2020, this increased to 35 days above 30 C. The average for Peterborough in the 1990s was only 10 days above 30 C. In a climate projection report done for the City of Peterborough, 23 days above 30 C will be the norm by the 2030s.

Looking to the future

According to “Climate Change Research Report CCRR-44” by the Ontario Ministry of Natural Resources and Forestry (2015), winter temperatures in the Great Lakes Basin region, which includes the Kawarthas, are projected to increase, on average, by 2.5 to 2.8 C in the 2020s, 3.5 to 5.3 C by the 2050s, and 3.5 to 8.6 C by the 2080s. Summer temperatures are projected to increase, on average by 2.0 to 2.1 C in the 2020s, 2.6 to 4.4 C by the 2050s, and 2.7 to 7.5 C by the 2080s. Winter warming is likely to exceed summer warming.

Month Normal (1971-2000)RecordedDifference
June 202416.8 C17.8 C (as of June 29)1.0 C warmer
May 202412.4 C14.3 C1.9 C warmer
April 20245.7 C7.1 C1.4 C warmer
March 2024-2.0 C2.3 C 4.3 C warmer
Feb. 2024-7.7 C-2.4 C5.3 C warmer
Jan. 2024-8.9 C-3.7 C5.2 C warmer
Dec. 2023-5.3 C0.4 C 5.7 C warmer
Nov. 20231.7 C1.5 C0.2 C cooler
Oct. 20237.3 C10.6 C3.3 C warmer
Sept. 202313.5 C15.5 C2.0 C warmer
August 202318.2 C17.9 C0.3 C cooler
July 202319.4 C19.9 C0.5 C warmer
June 202316.8 C17.2 C0.4 C warmer
May 202312.4 C 11.7 C0.7 C cooler
April 20235.7 C 7.7 C2.0 C warmer
March 2023-2.0 C-1.2 C0.8 C cooler
Feb. 2023-7.7 C-4.8 C2.9 C warmer
Jan. 2023-8.9 C-3.8 C5.1 C warmer
Dec. 2022 -5.3 C-2.8 C 2.5 C warmer
Nov. 20221.7 C 2.8 C1.1 C warmer
Oct. 20227.3 C 7.6 C0.3 C warmer
Sept. 202213.5 C 14.8 C1.3 C warmer
August 202218.2 C 19.2 C 1.0 C warmer
July 202219.4 C 20.1 C (Trent U. station. Missing data at Ptbo A)0.7 C warmer
June 202216.8 C 16.9 C0.1 C warmer
May 202212.4 C 13.7 C1.3 C warmer
April 20225.7 C 5.6 C0.1 C cooler
March 2022-2.0 C-1.3 C0.7 C warmer
Feb. 2022-7.7 C-7.9 C0.2C cooler
Jan. 2022-8.9 C-12.5 C3.6C cooler
Dec. 2021-5.3 C-1.3 C4.0C warmer
Nov. 20211.7 C 1.5 C 0.2C cooler
Oct. 20217.3 C 12.3 C5.0C warmer
Sept. 202113.5 C14.8 C1.3C warmer
August 202118.2 C21.0 C2.8C warmer
July 202119.4 C19.0 C0.4 C cooler
June 202116.8 C18. 8 C 2.0C warmer
May 202112.4 C11.6 C 0.8 C cooler
April 20215.7 C6.6 C1.3C warmer
March 2021-2.0 C0.6 C 2.6C warmer
Feb. 2021-7.7 C-8.1 C0.4C cooler
Jan. 2021-8.9 C-5.63.3C warmer
Dec. 2020-5.3 C-2.4 2.9C cooler
Nov. 20201.7 C4.8 C3.1C warmer
Oct. 20207.3 C6.9 C0.4C cooler
Sept. 202013.5 C13.8 C0.3C warmer
August 202018.2 C19.2 C1.0C warmer
July 202019.4 C22.6 C3.2C warmer
June 202016.8 C18 C 1.2C warmer
May 202012.4 C11.2 C 1.2C cooler
April 2020 5.7 C 4.2 C1.5 C cooler
March 2020-2.01.5 C3.5C warmer
February 2020-7.7 C-5.2 C2.5C warmer
January 2020-8.9 C-4.3 4.6C warmer
December 2019-5.3 C-4.31.0C warmer
November 20191.7 C-1.7 C
3.4C cooler
October 20197.3 C8.1 C
0.8C warmer
September 201913.5 C14.2 C
0.7C warmer
August 201918.2 C17.9 C
0.3 C cooler
July 201919.4 C20.9 C
1.5C warmer
June 201916.8 C16.3 C0.5 C cooler
May 201912.4 C11.1 C
1.3 C cooler
April 20195.7 C 5.0 C
0.7 C cooler
March 2019-2.0 C-2.2 C
0.2 C cooler
February 2019-7.7 C-6.1 C
1.6 C warmer
January 2019-8.9 C-9.7 C
0.8 C cooler
December 2018-5.3 C-2.8
2.5 C warmer
November 20181.7 C-0.9 2.6 C cooler
October 20187.3 C7.1 C
0.2 C cooler
September 201813.5 C15.9 C
2.4 C warmer
August 201818.2 C21.5 C  (Trent U. station)3.3 C warmer
July 201819.4 C21.8 C  (Trent U. station)2.4 C warmer
June 201816.8 C17.3 C0.5 C warmer
May 201812.4 C15.3 C2.9 C warmer
April 20185.7 C2.0 C3.7 C cooler
March 2018-2.0 C-1.2 C0.8 C warmer
February 2018-7.7 C-2.9 C4.8 C warmer
January 2018-8.9 C-8.40.5 C warmer
December 2017-5.3 C-9.1 C3.8 C cooler
November 20171.7 C1.4 C0.3 C cooler
October 20177.3 C10.5 C3.2 C warmer
September 201713.5 C16.1 C2.6 C warmer
August 2017 18.2 C16.7 C1.5 C cooler
July 201719.4 C19.3 C0.1 C cooler
June 201716.8 C16.9 C (Note: 129.9 mm of precipitation vs. 79.9 mm normal (1981 – 2010)0.1 C warmer
May 201712. 4 C12.1 C (Note: 187 mm of precipitation vs. 81.5 mm normal (1981 – 2010)0.3 C cooler
April 20175.7 C7.7 C (Note: 111.9 mm of precipitation vs. 68.6 mm normal (1981 – 2010)2.0 C warmer
March 2017-2.0 C-2.9 C0.9 C cooler
February 2017-7.7 C-3.0 C ( Trent University Station, since Ptbo Stn A data was incomplete)4.7 C warmer
January 2017-8.9 C-4.1 C4.8 C warmer
December 2016-5.3 C-5.2 C0.1 C  warmer
November 20161.7 C3.6 C1.9 C warmer
October 20167.3 C8.4 C1.1 C warmer
September 201613.5 C15.3 C1.8 C warmer
August 201618.2 C21.9 C3.7 C warmer
July 201619.4 C20.8 C1.4 C warmer
June 201616.8 C17.1 C0.3 C warmer
May 201612. 4 C12.5 C0.1 C warmer
April 2016 5.7 C 3.6 C2.1 C cooler
March 2016-2.0 C-0.5 C1.5 C warmer
February 2016-7.7 C-5.8 C1.9 C warmer
 January 2016 -8.9 C-6.8 C2.1 C warmer
December 2015-5.3 C2.6 C7.9 C warmer
November 20151.7 C4.7 C3.0 C warmer
October 20157.3 C7.8 C0.5 C warmer
September 201513.5 C16.9 C3.4 C warmer
August 201518.2 C18.4 C0.2 C warmer
July 201519.4 C19.3 C0.1 C cooler
June 201516.8 C16.3 C0.5 C cooler
May 201512.4 C14.3 C1.9 C warmer
April 20155.7 C6.0 C0.3 C warmer
March 2015-2.0 C-4.4 C2.2 C cooler
February 2015-7.7 C-15.8 C8.1 C cooler
January 2015-8.9 C-9.9 C1.0 C cooler
December 2014-5.3 C-2.4 C2.9 C warmer
November 20141.7 C0.8 C0.9 C cooler
October 2014 7.3 C 9.2 C1.9 C warmer
September 201413.5 C14.1 C0.6 C warmer
August 201418.2 C17.6 C0.6 C cooler
July 201419.4 C18.2 C1.2 C cooler
June 201416.8 C17.7 C0.9 C warmer
May 201412.4 C13.6 C1.2 C warmer
April 20145.7 C5.3 C0.4 C cooler
March 2014-2.0 C– 7.3 C5.3 C cooler
February 2014-7.7 C-11.5 C3.8 C cooler
January 2014-8.9 C-9.9 C1.0 C cooler 
December 2013-5.3 C-7.4 C2.1 C cooler
November 20131.7 C0.1 C1.6 C cooler
October 20137.3 C9.1 C1.8 C warmer
September 201313.5 C13.8 C0.3 C warmer
August 201318.2 C18.2 C0 
July 201319.4 C20.4 C1.0 C warmer
June 201316.8 C17.0 C0.2 C warmer
May 201312.4 C13.7 C1.3 C warmer
April 2013 5.7 C  5.0 C0.7 C cooler
March 2013-2.0 C-1.2 C0.8 C warmer
February 2013-7.7 C– 7.0 C0.7 C warmer
January 2013-8.9 C-4.7 C4.2 C warmer
December 2012-5.3 C-1.6 C3.7 C warmer
November 20121.7 C1.7 C0
October 20127.3 C8.6 C1.3 C warmer
September 201213.5 C13.2 C0.3 C cooler
August 201218.2 C18.5 C0.3 C warmer
July 201219.4 C20.8 C1.4 C warmer
June 201216.8 C18.2 C1.4 C warmer
May 201212.4 C14.2 C1.8 C warmer
April 20125.7 C5.9 C0.2 C warmer
March 2012– 2.0 C5.0 C7.0 C warmer
February 2012-7.7 C-2.5 C5.2C warmer
January 2012-8.9 C-4.2 C4.7 C warmer
December 2011-5.3 C-1.4 C3.9 C warmer
November 20111.7 C4.3 C2.6 C warmer
October 20117.3 C9.2 C1.9 C warmer
September 201113.5 C16.2 C2.7 C warmer
August 201118.2 C19.1 C0.3 C warmer
July 201119.4 C20.9 C1.4 C warmer
June 201116.8 C17.6 C1.4 C warmer
May 201112.4 C13.6 C1.8 C warmer
April 20115.7 C5.9 C0.2 C warmer
March 2011-2.0 C-1.6 C0.4 C warmer
February 2011-7.7 C-7.0 C0.7 C warmer
January 2011-8.9 C-9.9 C1.0 C cooler
December 2010-5.3 C-6.1 C0.8 C cooler
November 20101.7 C2.7 C1.0 C warmer
October 20107.3 C8.4 C1.1 C warmer
September 201013.5 C14.4 C (Trent U. Weather Station)0.9 C warmer
August 201018.2 C19.6 C (Trent U. Weather Station)1.4 C warmer
July 201019.4 C21.8 C (Trent U. Weather Station)2.4 C warmer
June 201016.8 C17.7 C (Trent U. Weather Station)0.9 C warmer
May 201012.4 C14.1 C (Trent U. Weather Station)1.7 C warmer
April 20105.7 C9.6 C  (Trent U. Weather Station)3.9 C warmer
March 2010-2.0 C2.9 C  (Trent U. Weather Station)4.9 C warmer
February 2010-7.7 C-5.2 C (Trent U. Weather Station)2.5 C warmer
January 2010-8.9 C-7.6 C (Trent U. Weather Station)1.3 C warmer