Marine wind maps: description and legend


Winds vary, often dramatically, in space and time. Winds near the shore can vary from those offshore, depending on the shape and orientation of the land. These maps allow one to visualize the complexity of the winds.

The map represents the 0.995 eta wind (i.e. the wind at approximately 40 meters above the water).

The winds are calculated by Environment and Climate Change Canada's numerical model of the atmosphere from the operational Global Environmental Multi-scale (GEM) model run twice daily (00:00 UTC and 12:00 UTC).

WindVis Application

The Canadian Ice Service's WindVis application allows users to select a marine region and a model issue time, then animate the corresponding sequence of marine forecast wind charts.

Click to access the WindVis application.


Wind visualization products are not currently archived. Approximately one month of daily model outputs are accessible with this application.



Legend defining line symbols found on marine wind maps
Symbol Description
 Pressure symbol - Black Pressure Gradient
The black lines represent the isobars which connect points of equal atmospheric pressure. Each line is assigned a value in hectopascals (hPa), plotted at 4 hPa intervals from the main isobar at 1000 hPa.
 Temperature symbol - Blue

Temperature Threshold (-4°C)
The blue line depicts the -4° Celsius air temperature threshold, which is used as a guideline for forecasting freezing spray.

The threshold represents the boundary between air colder and warmer than -4°C. This gives a rough estimation of where freezing spray might be encountered. Other factors such as wind speed and the amount of sea ice present should be considered when predicting freezing spray.

 Region symbol - Red Marine Regions
The red line is used to delimit marine weather regions.

Wind Barbs

Wind barbs indicate the wind speed and wind direction.  The symbol illustrates the direction of the wind travelling from the barbs to the solid dot.

Legend defining wind barb symbols found on marine wind maps
Symbol Description
 Wind barb - less than 5 knots No Barb
A bar with no barb indicates a wind speed less than 5 knots (kts)
 Wind Barb - 5 knots Half Barb
Each half barb (short bar) represents 5 knots (kts)
 Wind Barb - 10 knots Full Barb
Each full barb (long bar) represents 10 knots (kts)
 Wind Barb - 50 knots Triangle
Each triangle represents 50 knots (kts)

Wind Barb Colours

Legend defining colour ranges of wind barb symbols found on marine wind maps
Symbol Description
 Green - Light Wind Green
Less than 10 knots
  Blue - 10-15 kts Light Blue
10 to 20 knots
 Blue - 25 kts Dark Blue
25 to 30 knots
 Red - 35 kts+ Red
35 knots or more

Time Intervals

T+hh refers to the forecast’s time interval (hh), in hours, from the hour T of the model’s initial run time. The model is run every 12 hours, at 00:00 UTC and 12:00 UTC. A chart is produced for each 3 hour interval thereafter, such as T+00, T+03, T+06, etc.

For example, if the model is run at 12:00 UTC, the T+03 chart would display the winds forecast for 15:00 UTC.

Additional Information

Model Details

T+0 to T+48
Wind barbs are displayed at intervals between 24 km and 72 km, depending on the region, using Global Environmental Multi-scale (GEM) Regional model. See also Regional Deterministic Prediction System (RDPS)
T+60 to T+120
Wind barbs are displayed every 150 km using Global Environmental Multi-scale (GEM) Global model. See also Global Deterministic Prediction System (GDPS)

Marine Weather Guide

Consult the National Marine Weather Guide for more information about marine weather charting.

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