Map of Simcoe Muskoka

Environment

Extreme Temperature

Extreme Heat

Extreme Cold

Temperature extremes can pose a risk to human health and to infrastructure. The SMDHU Climate Change Story Map and Vulnerability Assessment describe the potential impacts of such extremes.

There are three weather stations in the Simcoe and Muskoka region which are used to monitor and report on temperature and precipitation in the region. Environment and Climate Change Canada operate and report on data obtained from these weather stations. The stations are categorized as: Barrie-Oro (near Barrie), Egbert (in Essa), and Beatrice (near Bracebridge).

Extreme heat

There is a general warming trend throughout our region, with climate change projected to increase the number of extreme heat events. Extreme heat can cause serious or life threatening health effects including dehydration, heat exhaustion, and heat stroke. Extreme heat can also trigger or exacerbate mood and behavioural disorders, interact with prescription medications, and affect prescription medication storage. Populations most at risk to the effects of extreme heat include children, seniors, pregnant women, outdoor workers, people with pre-existing mental illness, people taking psychotropic medications, homeless or underhoused people, and people living without access to air conditioned spaces.

Extreme heat events

Environment Canada issues heat warnings to warn about the effects of extreme temperatures. For the Simcoe and Muskoka regions, heat warnings are communicated when temperatures are expected to reach 31°C or higher and nighttime minimum temperatures are 20°C or higher for two (or more) days in a row, or when humidex values are expected to reach 40 or higher. To learn more about the humidex, please visit the Environment Canada page on warm weather hazards.

From 2001 to 2018, there was an average of 1.5 extreme heat days each year across the health unit region, which corresponds to approximately one extreme heat event (2+ days meeting criteria) each year. There were fewer extreme heat days reported in Muskoka than at the two Simcoe County weather stations. There is no clear pattern, although there were notable spikes in the number of extreme heat days in 2001, 2002, and 2005, especially at Egbert weather station which is in South Simcoe. 2005 was the warmest summer on record in Ontario. No extreme heat days were reported in 2004, 2008, 2009, and 2014 to 2017.

191126ExtremeHeatDays2001to2018

Tropical nights

Tropical nights, a climate change indicator, describes days where the daily minimum temperature remains above 20°C. Lower overnight temperatures are important for relief during the warm summer months. When minimum (overnight) temperatures remain elevated (>20°C) the risk and severity of heat-related health impacts increases. Cool relief in the evening is particularly important for at-risk populations and individuals with limited access to home cooling. The number of tropical nights is expected to increase with climate change.

Community design is an important factor in extreme heat. Cities and towns will experience extreme heat and tropical night impacts more than surrounding rural areas. This is due to the Urban Heat Island (UHI) effect. The UHI effect describes why we see differences in temperatures between urban and rural areas. Areas with higher building density, more paved surfaces, and reduced greenspace have been shown to trap and amplify heat. In contrast, rural areas tend to have greater tree canopy and other cooling characteristics. Increasing urbanization in our region, particularly in the southern part of Simcoe County, paired with an increase in extreme heat as a result of climate change will lead to more tropical nights in our region.

From 2001 to 2018 there was an average of two tropical nights per year across the health unit region. Most of these were observed at the Simcoe County weather stations (Barrie-Oro and Egbert). Barrie-Oro reported a large number of tropical nights in 2001 (8) and 2002 (13), before dropping to two or fewer tropical nights most years. A higher number of tropical nights were observed on average in Egbert, which is the most southern weather station in the region.

191126TropicalNights2001to2018

Extreme cold

Average winter temperatures are expected to increase in our region. Increased winter temperatures will support an overall decrease in exposure to extreme cold events. Even with milder winter temperatures, there is still the potential for extreme cold events to result in health impacts. Individuals will be less acclimatized to winter weather, which can result in more severe impacts when extreme cold events occur. Exposure to cold is associated with a number of health impacts including increases in blood pressure, cholesterol, and cardiovascular mortality. Even exposure to moderate cold temperatures can increase cold-related health outcomes and mortality.

Extreme cold events

Environment Canada's criteria for issuing an extreme cold warning is when temperatures fall to or are expected to reach -30°C for at least two hours in Simcoe County and -35°C for the District of Muskoka.

From 2001 to 2018, the criteria for extreme cold was met with an average of 1.1 days per year across the region. The number of days meeting extreme cold warning criteria varied from year to year, across the three weather stations in the health unit region: Egbert (South Simcoe), Barrie-Oro (North Simcoe), and Beatrice (Muskoka). Particularly cold winters were experienced in 2003/2004, 2008/2009, and 2013/2014. In 2003/2004, there were seven days meeting the criteria for extreme cold at Barrie-Oro. Despite being a generally warm winter, a period of deep freeze was experienced in early 2004 across Canada.

191126ExtremeColdDays2001to2018