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Oak Ridges Moraine Groundwater Program

Climate summary, a regional look

This snapshot provides a regional overview of the climate data held in the ORMGP, and allows for long-term (last ten years) average temperature and precipitation values to be quickly viewed across the study area. The temperature and precipitation data held in the ORMGP are updated on a nightly basis from Environment Canada’s website. For the ORMGP study area, the presented values can be considered to be an update from the last comprehensive overview of Ontario’s climate data, which was prepared in 1980 by the then Ministry of Natural Resources (Brown, 1980). This report is held in the ORMGP Library and can be viewed by program partners here.

In the upper map, the active climate stations are colour coded based on the ten year average precipitation. Stations with the greatest annual average precipitation, (of greater than 1,100 mm/yr) are found inland from Georgian Bay and Lake Ontario in the north parts of the ORMGP study area. Stations with the lowest precipitation, (of around 700 mm/yr) are generally found along the Lake Ontario shoreline.

The lower map shows the active climate stations colour coded based on the ten year average temperature. Stations with the highest annual temperature, of around 10°C, are found along the Lake Ontario shoreline in the heavily urbanized cities or Toronto, Hamilton and Mississauga. In the northerly parts of the ORMGP study area, inland from Georgian Bay, are the stations with the lowest average temperature of between 5°C and 6°C. The moderating influence of the Great Lakes can be observed by comparing the average temperatures at stations closer to Lake Huron and Lake Ontario to stations further inland from the lakes.

Data processing

In the maps below, climate stations having recorded precipitation or temperature data for at least 80% of the past 10 years are shown.

Precipitation is summed and air temperature is averaged for every water year (Oct-Sept). Minimum, mean, and maximum values of these annual sums/averages are posted once a station is clicked.

click on any circle to reveal station summaries. Full-screen available in the top-left corner