Ontario Has Been Getting Hotter

--Ontario Seasonal Temperature Changes Analysis for Historical Period (1951-2015)

Ziwang Deng, Xin Qiu, Xiaolan Zhou, Huaiping Zhu*

LAMPS,Department of Mathematics and Statistics,York University

*Project Leader: Professor Huaiping Zhu



Inspired by a news article published on New York Times on July 28, 2017 [1] based on work carried out by Dr. James Hassen on global and hemispheric analyses[2], the York University LAMPS group did similar analyses for Ontario. The following animations clearly show that Ontario has been getting hotter – extreme hot events occurred more and more frequently in recent decades; and this is more apparent in the annual (Fig. 1) and winter (Fig.2) average temperature plots.


Plotted in the following animations are frequencies of occurrence (y-axis) of Ontario local seasonal and annual temperature anomalies (dT) (at 608 CRU TS3.24.01[3] grid points within Ontario) divided by local standard deviation (δ, x-axis) obtained by binning all local results and 11-year period into 0.05 frequency intervals. Area under each curve is unity. Standard deviations are for the 1951-1980 period[1][2]. The vertical dashed lines are used to separate the events classified as

  • Extreme Cold:dT<-3δ
  • Cold:-3δ<=dT<-0.43δ
  • Normal:-0.43δ<=dT<0.43δ
  • Hot:0.43δ<=dT<3δ
  • Extreme Hot:dT>3δ


annual temperature

Figure 1 Frequency of occurence of local annual temperature anomalies

winter temperature

Fiure 2 Same as Figure 1 but for winter temperature

summer temperature

Figure 3 Same as figure 1 but for summer temperature

spring temperature

Figure 4 Same as figure 1 but for spring temperature

winter temperature

Figure 5 Same as figure 1 but for autumn temperature




[3]University of East Anglia Climatic Research Unit; Harris, I.C.; Jones, P.D. (2017): CRU TS3.24.01: Climatic Research Unit (CRU) Time-Series (TS) Version 3.24.01 of High Resolution Gridded Data of Month-by-month Variation in Climate (Jan. 1901- Dec. 2015). Centre for Environmental Data Analysis, 25 May 2017. doi:10.5072/3df7562727314bab963282e6a0284f24. http://dx.doi.org/10.5072/3df7562727314bab963282e6a0284f24

Ontario Climate Change Projections (www.yorku.ca/occp/)