Wind Rose: Days, Months and Seasons

The wind roses

The rose for the last hour, minute by minute, stays on the station’s own site: live one-hour wind rose.

What a wind rose shows

A wind rose is a compass with petals. Each of the 16 petals points to a compass direction, and its length shows how often the wind blew from that direction. Weather services always name wind by where it comes from: Environment and Climate Change Canada (ECCC) defines wind direction as the direction the wind blows from, so a west wind blows from the west toward the east.

The colours inside each petal split it by speed, from light blue for light breezes to near-black for gales. The circle in the middle holds the calm hours, when there was no wind to speak of, because calm air has no direction.

How to read it

1. Find the longest petal. That’s where the wind came from most often in that period. The text under each rose names it and gives its share of the hours.
2. Read the rings. The dashed circles are marked in percent of hours. A petal that reaches the 20% ring means the wind came from that direction one hour in five.
3. Look at the colours. A petal with lots of dark blue means that direction brings strong wind. A long but pale petal means frequent, gentle breezes.
4. Check the middle. The calm circle shows the share of hours with almost no wind.
5. Check how much data is behind it. Each rose says how many hours it’s based on, and since when. A rose built from a few days can look very different next month. Give it a full year before you trust the seasons.

Every rose also has a Show the numbers table with the percentage for each direction and speed, for anyone who prefers figures to pictures.

The speed colours

The speed groups follow the Beaufort wind scale that ECCC publishes, converted to km/h. A few neighbouring Beaufort numbers are combined so the rose stays readable.

The station reports wind in knots, and the tool converts at 1 knot = 1.852 km/h. The rose uses the station’s average wind at each reading, not the gusts, so gusty days look calmer here than they feel on a bike. For gusts, check the forecast page or the live readings on westlethbridgeweather.com.

How the log works

Once an hour, this site reads the latest file from Gary’s station and keeps one reading for that hour: the average wind speed, the gust, the direction and the temperature. If the station’s file is more than 45 minutes old, that hour is skipped rather than filled with an old reading, so a power cut or an internet outage leaves a gap instead of a wrong number.

• Last 24 hours and last 7 days roll forward every hour.
• This month starts fresh on the 1st, Alberta time.
• Seasons are whole months, the way ECCC groups them in its seasonal climate summaries: winter is December to February, spring March to May, summer June to August and fall September to November.
• All time covers up to the last three years. Older hours are dropped to keep the log small.

One reading an hour is a sample, not every gust and lull, but over weeks and months it builds a fair picture of our wind. Gary’s station sits on the west side of the coulees, so its wind can differ from the airport’s, south-east of the city.

Sources

• Environment and Climate Change Canada, Climate glossary (wind direction, calm): climate.weather.gc.ca
• Environment and Climate Change Canada, Beaufort wind scale table: canada.ca
• Environment and Climate Change Canada, Climate Trends and Variations Bulletin, Winter 2024/2025 (December to February): canada.ca
• Environment and Climate Change Canada, Climate Trends and Variations Bulletin, Spring 2025 (March to May): canada.ca
• Live readings: Gary’s West Lethbridge weather station, westlethbridgeweather.com