Jan: 50 Indian Bay 22/1942; -63 Norway House 9/1899
Feb: 60 Emerson 25/1958; -61 Brochet 18/1966
Mar: 76 Dauphin 24/1993; -56 Bird 10/1963
Apr: 99 Emerson 27/1952; -36 Ruttan Lake 2/1982
May: 106 Emerson & Deloraine 30/1934; -13 Churchill 4/1983
Jun: 108 Brandon & Minnedosa 17/1931; 14 Gillam 2/1977
Jul: 112 Emerson & St Albans 11/1936; 24 Birtle 6/1934
Aug: 106 Starbuck 6/1988; 16 Russell 31/1886
Sep: 103 Starbuck 2/1983; 6 Russell 28/1945
Oct: 92 Altona 1/1992; -25 Brochet 27/1972
Nov: 77 Altona 5/1975; -44 Brochet 27/1966
Dec: 61 Deloraine 3/1925; -60 York Factory 31/1900
Jan: 64 Windsor 25/1950; -73 Iroquois Falls 23/1935
Feb: 69 Windsor 26/2000; -62 Hornepayne 1/1957
Mar: 80 Windsor 30/1986; -50 Crystal Falls 3/1950
Apr: 90 Toronto 22/1842; -37 Central Patricia 6/1972
May: 97 Owen Sound 19/1911; -11 White River 1/1903
Jun: 104 Pickle Lake 19/1933; 10 Hornepayne 2/1919
Jul: 108 Ft Frances 13/1936; 15 Hornepayne 8/1922
Aug: 104 Harrow 6/1918; 19 Hornepayne 29/1922
Sep: 100 Toronto 2/1953; 0 Ft Frances 21/1949
Oct: 90 Windsor 6/1963; -17 Hornepayne 28/1933
Nov: 79 Windsor 1/1950; -47 Emo Radbourne 29/1985
Dec: 68 Toronto 3/1982; -62 Hornepayne 27/1933
Jan: 63 Ormstown 15/1995; -60 Ft McKenzie 19/1946
Feb: 64 Ormstown 22/1981; -66 Doucet 5/1923
Mar: 78 Oka 28/1945; -53 Poste Montagnais 13/1984
Apr: 87 Ste Martine 27/1990; -35 Doucet 1/1923
May: 96 Ville Marie 29/1929; -20 Ft McKenzie 1/1947
Jun: 100 Ville Marie 11/1956; 14 Poste Montagnais 5/1992
Jul: 104 Ville Marie 6/1921; 20 Inukjuak 8/1937
Aug: 98 Ste Martine 2/1975; 23 Fermont 31/1996
Sep: 93 Ormstown 5/1973; 5 Fermont 30/1992
Oct: 85 Ste Martine 2/1968; -9 Poste Montagnais 22/1974
Nov: 75 Oka 8/1938; -35 Poste Montagnais 20/1986
Dec: 68 Ormstown 5/2001; -56 Poste Montagnais 13/1980
Jan: 64 Maple Creek North 22/1981; -67 Butte St Pierre 25/1972
Feb: 67 Maple Creek North 27/1992; -70 Prince Albert 1/1893
Mar: 77 Midale 27/1946; -59 Key Lake 4/1995
Apr: 94 Beechy 29/1939; -41 Carswell Lake 1/1982
May: 105 Cypress Hills 29/1988; -16 Uranium City 4/2002
Jun: 110 Kincaid 5/1988; 18 Waseca 2/1919
Jul: 113 Midale & Yellow Grass 5/1937; 25 Waseca 24/1918
Aug: 110 Maple Creek North 5/1961; 23 Midale 24/1934
Sep: 104 Lost River 4/1940; -4 Cameo 30/1961
Oct: 93 Abbey 1/1957; -22 Val-Marie 29/1991
Nov: 78 Beechy 7/1999; -49 Prince Albert 23/1884
Dec: 69 Aneroid 5/1939; -59 Pilger 28/1917
So I took a (relatively) quick look at these provinces, just to see if I can add anything. I want to emphasize that I'm not doing an exhaustive search, and I'm not even cross-checking every month for which you have records already listed (to see if inactive stations were warmer/colder). I'm only doing that for some of the months, which had events that appear more interesting to me. Its entirely subjective, and there's plenty of room for further research here. I'm really only looking at events (warm and cold) that I'm already familiar with from research in previous years, most of which produced anomalous readings in adjacent parts of the US that I can easily cross reference. I suggest you do the same at some point if you're truly interested in expanding your database, above and beyond what I'm able to provide.
-Boissevain hit 54F in January 1944 (MSP had a 58/42 day). 55F at Wilson Creek Weir CS in January 1981 (MN state record of 69F for Jan also in 1981).
-Readings of 61F at Pine River and Swan River 2 in February 1992.
-Significantly warmer readings for March than what you have listed, and from multiple other months. This was the case with BC for March as well, where I listed 81F at Stave Falls in 1923 (searched because downtown Portland hit 82F) but also March 1930 hit 80F at Alberni Beaver Creek (searched because downtown Portland hit 83F), two different stations hit 80F in March 2004, and there were other events that brought upper 70's that your data dump appears to have missed, including three different stations @ 79F in March 1994. For Manitoba, the great March heat wave of 1910 (which was referenced quite a bit during the "Summer in March" heat wave of 2012) brought maximum readings of 83F to Morden and 80F to St. Albans (also MN state record for March of 88F). March 1946 produced 77F readings at two different stations, as did March 2012 (Hodgson 2 and Pinawa WNRE in the case of 2012). I just want to be clear that I'm not ragging on your method and I appreciate the work that you've done, I'm mostly lamenting the fact that there isn't a more comprehensive data dump available. At least not publicly available on the internet.
-I'm not sure about the Bird reading on 3/10/1963. Possibly bogus. Next lowest temp that month in MB was -40F. March 1972 brought -55F to Thompson and the reading is much better corroborated, with three other stations at -49F or lower.
-May 1934 maximum was 108F at Morden CDA.
-August 1988 maximum @ Starbuck was 107F not 106F (41.5C).
-November 1999 hit 78F at Plum Coulee.
-November 1985 hit -45F at Boggy Creek. I'm sure the real record for November would have been set in 1896 but there just wasn't enough station coverage in MB to capture it, especially in the typically colder areas up north. There were only two stations above 53N operating in MB in November 1896, and none above 54N. As it was, Brandon (a southerly town that's typically nowhere near the coldest location in the province) bottomed out at -41F that month. And on that note, this is actually a problem with most of the monthly extreme minimum records that you, myself, or anyone else will try to come up with. The majority will skew towards the present since there weren't enough (or in some cases, any) stations in the colder, more remote areas of each province in question to capture the colder airmasses of the past, in any given month. Even the records that we do have from some of those earlier events (like the August 1886 record in MB, for example), are most likely not representative of the actual coldest readings in the province that month - which of course wouldn't have been captured due to lack of stations.
-Three different stations hit 64F in December 1939, which of course set numerous monthly state records across the northern tier of the US as well.
-Cypress Hills hit 66F in January 2003.
-Prince Albert also hit -55.0C (-67F) in January 1886, the same cold wave that brought -57F to Edmonton (all time record low there which was tied in 1893, when Prince Albert hit -70F). January 1916 is a good candidate for a possible provincial record for the month (if we had more station coverage), as two different stations hit -65F in Saskatchewan. Also Camp Crook, SD hit -57F on 1/12/1916 which was the state record low until McIntosh hit -58F in February 1936.
-February 1992 maximum was 71F at Golden Prairie.
-March 1910 was warmer in SK as well. Maximum of 85F at Muenster, although that reading looks suspect. The next warmest reading was 79F, set at three different stations. Leader Airport hit 80F in March 2004. If we discount the Muenster reading from 1910, then the Leader reading from 2004 is the preliminary record.
-I wouldn't be surprised if the real record low for March was set somewhere in 1897, in an area where no stations existed. Glasgow, MT hit -45F on the 12th. Moose Jaw and Indian Head both hit -48F in SK, but both are southern towns and nowhere near the coldest areas of the province. There were only three stations above 52N operating in SK that month.
-April 1939 maximum was 96F at Rosetown.
-June 1919 minimum was 15F at Macklin.
-Illerbrun hit 95F in October 1943.
-Willow Creek hit -25F in October 1935. October 1919 is a possibility as well since three different stations hit -22F in SK, and even Bismarck, ND hit -10F.
-November 1999 maximum was 79F at Lake Alma and Stewart Valley.
-December 1939 maximum was 72F at Illerbrun.
-December 1917 minimum was -61F at Fond du Lac (59N). A rare example of a station existing in the far north 100 years ago, similar to Fort Vermilion in Alberta. Fond du Lac also hit -60F in December 1933.
Ontario and Quebec:
I'm going to be even less systematic here. Just a very cursory look:
-January 1950 had significantly warmer readings in Ontario. Five stations above 20C/68F, with a maximum of 72F at Niagara Falls.
-Another station in Windsor, ON hit 72F in February 2000, which was the highest reading that month in the province.
-March 2012 brought 84F to both Chatsworth and Ravenscliffe, ON.
-Atikokan, ON hit -52F in March 1943.
-It would be pretty obnoxious if 90F in Toronto from all the way back in 1842 was the Ontario record for April. I cross referenced Alpena, MI and saw that they hit 90F on 4/25/1990 and 4/16/2002. Checking ON numbers reveals a 92F at Pembroke in 2002 and three different stations at 91F in 1990. I'm sure a more comprehensive search would reveal even higher April readings on the books in Ontario.
-December 1982 had numerous warmer readings in Ontario. Six stations above 22C/72F, with a maximum of 73F at "Hamilton Municipal Lab."
-January 1995 produced 66F at St. Come de Liniere, QC. Impressive thaw that also brought 66F to Burlington, VT, their monthly record.
-January 1982 produced -62F at Riviere Kinojevis, QC.
-March 2012 brought 82F to Luskville and Sheenboro, QC.
-Sheenboro, QC also hit an incredible 94F in April 1976 (when Providence, RI hit 98F). However this reading is a bit suspect since the next highest maximum in the province that month was 88F. April 2002 also brought 90F to Charteris and Shawville, QC (when Central Park hit 96F to match its April record from 1976, a record that looked untouchable).
-August 1975 (possibly the greatest heat wave on record in this part of North America) produced significantly higher readings in Quebec. Three different stations hit 40C/104F and numerous stations over 100F. August 1935 (possibly the greatest heat wave on record in the Maritimes) deserves a special mention since it occurred mid-month and brought 103F to Chicoutimi, QC.
-September 1953 (102F in Central Park and 100F in Boston) brought 95F to three different stations in Quebec.
-November 1950 (84F in Central Park and 81F in Chicago-O'Hare) produced 77F at Coaticook, QC.
-December 2001 highest maximum was 70F at Hemmingford, QC.
-December 1933 also produced -56F at Doucet, QC.