Canadian Heat Waves Part 4

Top Ten Percent of Hottest Days

29 stations were selected to check for what is happening collectively with TMax. These stations were selected to have a start year before 1920 and have at least 95% of the records within their date range.

These are those stations:

StnID	Station	Province	Starts	Ends	Records	BaseTMax
1111	CRESTON	British Columbia	1912	2006	2700	31.1
1340	VAVENBY	British Columbia	1913	2009	2120	32.4
1835	CALMAR	Alberta	1916	2007	1965	28.2
1957	RANFURLY	Alberta	1905	1991	1613	29.1
2106	LACOMBE CDA	Alberta	1908	1993	1991	28.6
2205	CALGARY INT'L A	Alberta	1900	2009	2626	28.8
2247	GLEICHEN	Alberta	1903	2005	2297	30.2
2364	BANFF	Alberta	1900	1994	2360	27.2
2409	LAKE LOUISE	Alberta	1915	2007	2230	26.
2490	CAMPSIE	Alberta	1912	2009	1998	28.2
2658	BEAVERLODGE CDA	Alberta	1913	2007	1950	27.3
2973	MUENSTER	Saskatchewan	1904	2009	1930	30.1
3259	SCOTT CDA	Saskatchewan	1911	2009	1903	30.6
3270	WASECA	Saskatchewan	1907	2009	1927	29.4
3328	SASKATOON DIEFENBAKER INT'L A	Saskatchewan	1900	2009	2136	31.2
3533	RUSSELL	Manitoba	1912	1990	1631	30.1
3673	SPRAGUE	Manitoba	1916	1997	1533	30.6
380	BELLA COOLA	British Columbia	1900	2002	1859	28.3
3938	FORT FRANCES	Ontario	1913	1995	1346	30.6
3943	MINE CENTRE	Ontario	1915	2005	1562	30.5
3952	DRYDEN	Ontario	1914	1997	1129	29.7
4333	OTTAWA CDA	Ontario	1900	2010	1667	31.5
4547	BRUCEFIELD	Ontario	1903	1993	1115	31.2
5208	BERTHIERVILLE	Quebec	1919	1994	1118	30.5
5348	DRUMMONDVILLE	Quebec	1914	2009	1356	31.
588	FORT ST JAMES	British Columbia	1900	2009	2044	27.2
6158	FREDERICTON CDA	New Brunswick	1913	2000	1327	30.3
6527	CHARLOTTETOWN CDA	Prince Edward Island	1910	1992	1814	27.2

Each station had their top 10% of high TMax from July, regardless of the year, dropped into a table. Those in turn were baselined for each station from 1961 to 1990, the common range used in the science (for what ever reason they give).

From there the anomalies from those baselines were plotted for the entire dataset.

This is the highest TMax anomaly:

The over all trend is down, fewer hot days across all of Canada. The heat waves peaked in the 1940's, dropping until the 1980s, and flat since. 20 years of no change in heatwaves.

This is the average of the TMax anomaly:

Basically flat over all, with the 1920's to the mid 1940's dominating.

The lowest of the TMax anomalies will be very close to a flat line, no fluctuation because this dataset starts from a minumum value for each location to give the top 10%.

This is the number of days in each year. This had to be more restrictive in the stations, 1920 to 2005 was the cut off range. So no stations with a start year before 1920 and no stations with an end year before 2005. This is only 16 stations that met that criteria. If the entire dataset was used the count would be skewed, the numbers too low, because of missing stations in those outside years.

The trend is also dropping. Fewer days in Canada are above the top 10% temperature now than in the mid 1940's.

No matter how you slice the data, either looking at single stations, or collectively from a range of stations across Canada, the over all trend of TMax is to cooler temps.