Climate Resiliency

Ottawa is experiencing warmer, wetter and more unpredictable weather. On average, summers are getting hotter and winters less cold. While average total annual precipitation (rain and snow) has increased, it varies greatly both in terms of where and when it falls. Overall, Ottawa’s weather is becoming more variable and unpredictable, and we have experienced extreme heat, wind, rain and snow in recent years.

Some examples of extreme weather events in Ottawa include:

• Five successive ice storms in January 1998, which caused massive damage to trees and electrical infrastructure causing widespread power outages and a shutdown of activities across Ottawa and the region for several weeks. The ice storms was the second most expensive natural disaster in Canadian history.
• Over 50 cm of snow in February 2016, which caused closures throughout the city and set a new record for the biggest snowfall in a single day
• Significant flooding along the Ottawa River in the spring of 2017 and 2019 resulted in extensive property damage and health concerns
• Tornadoes in 2018 and 2019 caused extensive damage to property and power outages.
• A prolonged extreme heat event that lasted six days in July 2018. On Canada Day, at the hottest time of the day, humidex levels made it feel like 47 degrees Celsius.
• The Ontario-Quebec derecho in May 2022 that killed 10 people, caused widespread property damage and left hundreds of thousands of people in Ottawa without power for several days. The storm is the sixth most expensive natural disaster in Canadian history.

Climate science tells us that these trends will continue in the next decades. The City, in partnership with the National Capital Commission and Environment and Climate Change Canada, worked with climate scientists to develop climate projections for the National Capital Region. Climate projections use climate science and modelling to predict future changes in temperature, precipitation, wind and extreme weather. The study looked at projected changes until the year 2100.

What will Ottawa's climate look like in the future?

By the 2050s, under a high-emission scenario, the National Capital Region is projected to change in the following ways:

Temperature

• Average annual temperature will increase by 3.2 degrees Celsius
• There will be four times as many very hot days over 30 degrees Celsius – that’s an increase to 43 days per year from the current 11
• The number of days below -10 degrees Celsius will decrease by 35 per cent

Seasons

• Spring will start two weeks earlier
• Fall will start three weeks later
• Winter will be shorter by five weeks
• Winter freeze-thaw events will increase by 33 per cent

Precipitation

• Precipitation will increase in spring, winter and fall by eight per cent
• The maximum daily precipitation will increase by 14 per cent
• Annual snowfall will decrease by 20 per cent

Extreme events

• Possible increases in freezing rain
• Warming favours the conditions for storms, tornadoes and wildfires

The rate and extent of climate change will depend on future global greenhouse gas emissions. Significant global action is required to reduce emissions below the high emission scenario.

You can find more details of what to expect in the 2030s and 2080s in the Summary of Future Climate in Canada’s Capital Region.

The Climate Projections for the National Capital Region study was developed in partnership with the National Capital Commission and Environment and Climate Change Canada. It uses advanced climate science modeling to predict changes in temperature, precipitation, wind and extreme weather until the year 2100. 

• Executive Summary – provides a summary of the study and its key findings
• Volume 1 – provides an overview of the project methodology, findings and implications. It includes results and interpretation for key climate indices.
• Volume 2 – provides plots and tabular data for all the climate indices.

A complete and updated version of the datasets presented in this report is available at Open Ottawa:

• Appendix G – Table of Climate Indices
• Table 2.1 Projects for Extreme Precipitation Based on Multiple Methods
• NetCDF files for the climate indices

The online dataset includes Excel versions of the results in Appendix G and Table 2.1 as well as NetCDF files with more detail than the report (for example, indices calculated for each model and cell). Additional details on the data are also provided on Open Data (for example, model names for each index). Any minor updates to the data sets will be added to Open Ottawa. Please note there may be minor discrepancies between Open Ottawa and the report. If this occurs, the Open Ottawa version should be used.

Impacts of a changing climate

Climate change will impact us all in our daily lives in several ways. For example, more heat waves will increase heat related illnesses, especially for the most vulnerable. Shorter, warmer winters will negatively impact winter recreation. With increased extreme weather events we could see more damage to homes, power outages and strain on emergency services.

It will also impact the way the City operates and plans. Shifting freeze-thaw cycles can damage roads and other infrastructure and more intense rainfall can overwhelm sewer systems and increase the risk of flooding.

There will likely be some positive impacts too. Longer warmer seasons could benefit agriculture and construction. However, warmer weather and changing precipitation patterns will affect ecosystems and may increase conditions for diseases such as Lyme’s disease and West Nile virus.

The impacts of climate change will be looked at in further detail as a part of the climate vulnerability assessment.

City departments work together to understand and reduce the impacts of climate change. Current climate resiliency initiatives include:

• Environmental health warning and response programs to reduce illnesses and deaths associated with extreme heat and humidity, cold weather, and poor air quality.
• An Emergency Management Plan to prepare and respond to the needs of the community during a major emergency, while still ensuring continuation of essential services
• Applying a climate lens to the New Official Plan and its supporting documents to build energy and climate resiliency into future growth and development. The preliminary policy directions recommend climate change mitigation and adaptation policies throughout the plan.
• Using urban heat island maps to better understand what areas are impacted by hot weather, and to inform policies that will reduce the urban heat island effects to better protect public health.
• Applying a climate lens to asset management and capital projects to build resiliency of existing infrastructure.
• Building our infrastructure to be resilient in future climate conditions such as extreme weather, greater rainfall and higher temperatures. For example, the City’s wastewater treatment plant is being upgraded to permit the plant to operate independent of the utility grid, using power produced on site to so it can remain operational in the event of a sustained power failure.
• Growing Ottawa’s urban forest and making it healthier, more diverse and resilient through the Urban Forest Management Plan.

Flood risk management

• Every year the City activates a dedicated Spring Freshet Task Force to monitor the potential for spring floods and respond accordingly.
• The City works with Conservation Authorities to take preventative steps to protect homes from the spring snowmelt or freshet. This includes blasting ice on some sections of the Rideau River and flood monitoring and warning systems. The City also clears debris from storm water drains to prevent overland flooding.
• Designing stormwater infrastructure to accommodate increased flows and protect the Ottawa River through the Ottawa River Action Plan. For example, the Combined Sewage Storage Tunnel will reduce the frequency of sewage overflows entering the Ottawa river during storms.
• Providing grants to homeowners to reduce the risk of flooding through the Residential Protective Plumbing Program.
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• Updating floodplain mapping and community risk profiles to better understand and reduce potential risks from both riverine and urban (basement or overland) flooding. This interactive flood plain map shows three different flood events: a large flood event (1 in 50-year), regulatory flood event (1 in 100-year) and a more extreme flood event that could occur with climate change (1 in 350-year).
• Encouraging and supporting residents to take action on their property to reduce harmful impacts of rainwater run off through the Rain Ready Ottawa pilot program.

There are several things you can do to become more resilient to the impacts of changing weather patterns and extreme events.

Protect your home from flooding

• Manage rainwater on your property by redirecting your downspout to a permeable surface like lawn or garden. Residents can also help by using a rain barrel, installing a rain garden and replacing asphalt driveways with a permeable alternative. The City’s Rain Ready Ottawa program offers guidance and rebates of up to $5,000 for eligible residents.
• Help keep storm drains clear by removing debris and snow so rain can enter and doesn’t flood our streets and homes. Use this interactive map in the winter to find your closest catch basin.
• Manage rainwater on your property by re-directing your downspout onto grass or gardens, capturing rainwater in a rain barrel and landscaping to encourage rain to filter into the ground. Find out how you can better manage your rainwater.
• Plant a tree in your garden and protect existing trees. They soak up rainwater, provide shade and cool our neighbourhoods.
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• Check the interactive flood plain map to review the potential risk to your property and take steps to protect it
• Check that you have the appropriate insurance. Insurance for sewer backup and flooding often has to be purchased separately. You can find more information from the Insurance Bureau of Canada.

Stay safe during extreme weather events

• Be a good neighbour - check in on others who might be alone or need support in a power outage or emergency
• Follow Ottawa Public Health’s tips for staying healthy during extreme heat and humidity
• Develop an emergency preparedness plan and kit

Stay safe outdoors

There are many health benefits of being active and enjoying the outdoors. However, it’s important to take precautions.

• Enjoy the sun safely. Wear a hat, sunglasses, and sunscreen with a SPF of at least 30 to protect yourself from the sun and reduce the risk of skin cancer. Find out more about sun safety.
• Use the Air Quality Health Index to help identify what the air quality around you means to your health.
• Dress for the weather. When it’s cold wear three layers as well as a hat, mittens, face cover and boots to protect you from hypothermia and frost bite. Read more cold weather tips.

Increasing temperatures and more variable precipitation creates opportunities for vector borne diseases, such as West Nile virus and Lyme disease to spread. Reduce your risk by:

• Protecting yourself from ticks by wearing long pants, using DEET and doing tick checks when outdoors in wooded areas or areas with tall grasses. Populations of blacklegged ticks are growing and expanding into new areas as the climate warms, increasing the risk of Lyme disease. Find out more about Lyme disease prevention.
• Draining standing water to reduce the breeding grounds for the mosquitoes that may carry West Nile virus. Find out more about reducing the risk of West Nile Virus.