Winter Ice Roads in Northern Ontario

Climate change is presenting significant challenges to the operation and maintenance of winter ice roads in northern Canada. Northern communities require data and tools to assess the viability of ice roads into the future. This case study will define and explore one climate index that can contribute to climate risk assessments for northern communities.


Winter ice roads typically operate from January to March, and represent a critical means of access for remote northern communities. Winter ice roads in northern Ontario service 31 remote First Nations communities, who rely on these roads for the economical transport of supplies during the winter months. A warming climate has already affected the length of time that winter roads can remain operational.

Analyzing the accumulation of Freezing Degree Days (FDDs) under different emissions scenarios can provide one indication of the viability and longevity of winter roads into the future. This type of information is important to consider in long-term community planning and decision-making.


Winter ice roads in northern Ontario link 31 remote First Nations communities that are otherwise fly-in only. The winter roads typically operate from January to March, and are essential for the communities they serve as they reduce the cost of goods and services by enabling the ground shipment of heavy and bulky goods in the winter months. First Nations community leaders are already reporting a reduction in the length of time that winter roads are accessible due to warming, and have concerns about the associated higher living costs and quality of life impacts.

“Climate change has dramatically reduced the length of time winter roads are accessible, causing shortages of food, fuel, and medical supplies and increasing the need to fly in supplies. This results in higher living costs and potential decreases in quality of life and health.”

-Isadore Day, Ontario Regional Chief for the Assembly of First Nations

Research was conducted to analyze trends in the seasonal timing of opening dates of the James Bay Winter Road as correlated with air temperature. The analysis found that a minimum of 380 Freezing Degree Days (FDDs) below 0°C during the period of road preconditioning was a critical factor in a favourable construction period (historically, the preconditioning period is from October 1 to December 31). However, the preconditioning period may shift into January as the climate warms, and the spring melt period will also start earlier than in the past. The focus of the analysis below is on the shifts in the timing of achieving this 380 FDD threshold during the preconditioning period.

Knowing this threshold value, it is possible to explore scenarios that examine the viability and longevity of winter roads over the coming century. FDD accumulations starting after September 30 (the traditional start of the preconditioning period) were examined for several communities served by winter road corridors (Big Trout Lake, Lansdowne House, Moosonee, Red Lake, and Kapuskasing) to assess trends in historical and projected FDD accumulations. The results of this analysis reveal that the date at which construction for the ice road can begin will shift through the century.

Warming will significantly affect winter road construction, maintenance, and use. Warming trends and associated decreases in the length of winter road seasons will therefore continue to have significant impacts on communities as winter roads are the most economical method for the transport of supplies.

As the warming climate is already having an impact on winter road construction, how long will winter roads be a viable way of accessing the communities they serve?

The challenge in answering that question is to identify the climate change variables and thresholds that are appropriate indicators of the length of operation of these roads. The opening of winter roads depends largely on sufficient ice development before construction, while the timing and operational length of these roads are affected by a variety of other climate factors including air temperature, precipitation, snow, and wind.

Freezing Degree Days (FDDs) begin to accumulate when the daily mean temperature drops below a certain threshold (commonly 0°C). If a day’s mean temperature is -21°C, for example, it increases the annual FDD value by 21. Days when the mean temperature is 0°C or warmer would not contribute to the annual sum.

High FDD values are associated with relatively cold conditions and likely imply greater snow and ice accumulation. If projections show a decrease in FDDs, then that location is likely to experience shorter or less severe winters.


When assessing trends for FDD accumulations starting on October 1st, the accumulation of 380 FDDs is projected to occur later in the year for all communities under all greenhouse gas emissions scenarios, when compared to historical conditions. For example, using the high emissions scenario (RCP 8.5), starting construction dates for the ice road are projected to occur between three to four weeks later for all five of the communities by the end of the century (Table 1). This analysis is based on the median date at which FDD accumulations reach 380 FDDs from the start of the preconditioning period (October 1st). For Moosonee, Red Lake, and Kapuskasing, the implication of this later freezing period is that construction would not be able to begin until the middle of January. For Big Trout Lake and Lansdowne House, the starting construction dates are projected to move to late December and early January.


Table 1. Median date at which 380 FDDs (Tmean ≤ 0°C) have accumulated from October 1st for RCP 8.5

Explore different results for different regions and emissions scenarios in Figure 1 below: Big Trout Lake, Lansdowne House, Moosonee, Red Lake, and Kapuskasing.

Figure 1. Freezing Degree Day accumulations for five communities

Day of the year when FDD (Tmean ≤ 0°C) accumulations are greater than 380 (starting from October 1st) for five communities.

Using the “Degree Days Below a Threshold” variable on the Analyze page (see Box 1 below), you can download data for your region of interest that identifies the date at which the threshold (in this case 380 FDDs) will be met in the winter season. With this analysis tool, you can specify the temperature threshold for degree days (either above or below a temperature threshold), as well as the total threshold of accumulated degree days.


As average winter temperatures continue to warm throughout Canada, the viability of winter ice roads is projected to decrease. Climatic conditions for preconditioning are projected to become less favourable for winter ice roads by the 2050s and into the 2080s for Moosonee and Kapuskasing, as the 380 FDD threshold is not projected to be met until well into January for these communities, which will result in delayed construction and opening dates of the ice road. Climate conditions may also significantly delay the opening of the ice road for Red Lake by the end of the century. However, climate conditions could remain favourable for preconditioning through the end of 2100 for Big Trout Lake and Lansdowne House. This analysis was based on the high emissions scenario (RCP 8.5), but as seen in Figure 1, a shortening of the winter road season is projected under the low (RCP 2.6) and moderate (RCP 4.5) emissions scenarios as well, albeit to a lesser extent.

This example only explores climatic conditions for the preconditioning period of ice road construction, but warming will also affect the length of time that the ice road can be maintained. It is projected that spring melt will also occur earlier as the climate warms. Consideration of the shortened access season for winter ice roads is important information for community decision-making, where reliable winter road access is less likely by mid-century. This information can be used to inform long-term strategic planning for communities.

Key Takeaways

  • Winter ice roads, such as the James Bay Winter Road in northern Ontario, are an essential means of access and ground transportation for remote First Nations communities.
  • Warming due to climate change has already shortened winter road season lengths, driving up costs of living and decreasing quality of life.
  • The number of freezing degree days (FDD) during the road preconditioning period is one critical indicator of winter road viability and longevity over the coming century.
  • By mid-century, climate conditions could significantly shorten the ice road season for several First Nations communities in northern Ontario. This is an important consideration for community decision-making and long-term strategic planning.

Box 1: Using the Analyze page to examine Freezing Degree Days (FDDs)

Click here to go to the Analyze page. Then:

  1. Choose the BCCAQv2 dataset.
  2. Select “Grids” under Select Locations.
  3. Choose your variable of interest – in this case, “Degree Days Below a Threshold.”
    • Enter the temperature threshold. A commonly used threshold for FDDs is 0°C.
    • Select a location on the map, or use the search bar in the bottom right corner to search for a location. Select the grid cells on the map for your location of interest.
  4. Select a starting year and ending year (minimum 30 year period recommended) under Choose a Timeframe.
  5. Under the Advanced section, specify the desired Models, RCPs, Percentiles, Temporal Frequency, and Output Format. Default values are pre-selected.
  6. Enter your email address and submit your request. The data will be processed and sent to you in the format requested.


Contributors: Lindsay Matthews, Kari Tyler, Elaine Barrow, Taylor Livingston, Amanda Patt, Stacey O’Sullivan, Nathalie Bleu, Jessie Booker.


This case study was inspired by and relied upon the following original research:

Hori, Y., Gough, W. A., Butler, K., & Tsuji, L. J. (2017). Trends in the seasonal length and opening dates of a winter road in the western James Bay region, Ontario, Canada. Theoretical and Applied Climatology, 129(3): 1309-1320.

Hori, Y., Cheng, V. Y., Gough, W. A., Jien, J. Y., & Tsuji, L. J. (2018). Implications of projected climate change on winter road systems in Ontario’s Far North, Canada. Climatic Change, 148(1): 109-122.