Ice and iceberg bulletin overview

Bulletins provide information on ice and iceberg conditions. The Canadian Ice Service provides the following bulletins:

• Ice Forecasts (with Ice Warnings)
• Iceberg Bulletins
• St.Lawrence River Ice Bulletins
• Seasonal Outlooks
• 30-Day Ice Outlooks
• Seasonal Summaries

To view the latest bulletins, click on the “Latest” links in the tables below, or use our "Product Search" application.

Ice Forecasts

These daily forecasts describe the ice edge using latitude and longitude coordinates and for each marine area, the total ice concentration, the predominant ice stage of development and the concentration of the oldest ice type. Warnings are issued as appropriate. The forecasts are valid from the time of issue until the end of the following day (so for a period of 24 to 48 hours).

These forecasts are important to mariners and shipping agencies requiring information on ice conditions that could affect their operations. They are issued when there is ice and marine activity in the area. The table below shows when they are usually available.

Ice Warnings

Ice warnings are part of the ice bulletins and provide notice of possible or increased risks of damage to vessels and equipment, and to the safety of marine navigation and marine activities due to ice.

The following types of ice warnings may be issued:

Rapid closing of coastal leads warning

A rapid closing of coastal leads warning will be issued when significant leads are expected to become blocked by six tenths or more of grey-white ice or older within a 12 hour period. To be considered significant the lead must be:

• At least 10 nautical miles wide
• At least 25 nautical miles long
• Contain no more than three tenths of ice

Ice pressure warning

Strong ice pressure occurs where a ship moves with the ice, and is not able to navigate. The ship may be pushed on the side or lifted. At the same time, ice ridges may be actively building.

Special ice warning

A special ice warning will be issued for the following situations:

• When one tenth or more of greywhite ice or older is expected to be in an area when ice is not normally present.
• Any unusual or significant ice event that is or could present a hazard to navigation.

Iceberg Bulletins

The iceberg bulletin describes the iceberg limit in Canada's East Coast waters, based on data gathered from ship reports, iceberg reconnaissance flights and occasionally from satellite. Information about the icebergs is put into a database then the positions are drifted to the valid time of the bulletin. The iceberg limit describes the furthest extent of the icebergs. When applicable, there may be a western limit in the Gulf of St Lawrence.

The iceberg limit is given by latitude and longitude coordinates. General information on the number of known icebergs within each marine area is also provided.

Iceberg bulletins are used by mariners and shipping agencies requiring information on conditions that could affect marine safety.

St.Lawrence River Ice Bulletins

These bulletins describe general current ice conditions for the St. Lawrence River from Montreal to Cabot Strait as well as a description of the ice type and concentration for sections of the river. They may recommend a particular shipping route, depending on conditions.

These bulletins are issued by the Canadian Coast Guard, with input from the Canadian Ice Service. Warnings are not a part of this bulletin. These bulletins are used primarily by mariners and shipping agencies to help plan their operations and routes, and are available from December to April.

Seasonal Outlooks

These outlooks give an indication of the expected timing of the ice breakup in the Arctic or freeze-up in the south for the season. The Great Lakes and the North American Arctic Waters Seasonal Outlooks are issued in partnership with the US National Ice Center under the North American Ice Service). These outlooks are not updated or amended and are removed from the website after 30 days.

To view the latest outlooks, please visit our "Product Search" page.

30-Day Ice Outlooks

These outlooks describe the general advance or retreat of ice in a region over a 30-day period. They also describe ice stage of development and identify areas and time periods in which conditions are expected to be more or less favorable than normal. They are issued on the third business day following the 1^st and 15^th of each month.

Each outlook is issued by the Canadian Ice Service in text format. In addition, the Hudson and Foxe, Eastern and Northern Arctic, Western and Central Arctic, and Great Lakes forecasts are also issued by the North American Ice Service in a graphic format.

These outlooks help shipping agencies and mariners plan their marine operations up to 30 days in advance.

Seasonal Summaries

These documents provide a post-seasonal summary of prevailing ice conditions and related weather. The Canadian Arctic summary is issued by the Canadian Ice Service in three time periods - Spring (February to May), Summer (June to October) and the period from November to January is described in the Arctic Annual Atlas. The Summer Summary includes the Labrador Coast when ice lingers beyond the end of May.

The Great Lakes Seasonal Summary is issued in partnership with the US National Ice Center under the North American Ice Service.