Cup counter anemometer.

Llansadwrn Weather Station:
Anglesey wind averages

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Wind direction

The prevailing wind blows from between S and W for 56% of the time. The least wind blows from the SE for only 5% of the time. It is rarely calm (only 2%).

Wind direction data for Anglesey.

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Wind Speed

Wind speed (based on mean hourly values) averages 13 mph and ranges between 10-15 mph in all months of the year. Lowest average speeds occur between April-August, but even the lowest in July is still more than 10 mph. Highest speeds are between September-March; the highest in December and January average more than 15 mph. The highest hourly mean speed of 65 mph was recorded in December 1966 and again on 24th December 1997.

Hourly mean wind speeds on Anglesey 1981-90.

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Distribution of Wind Speeds

The distribution of hourly mean wind speeds shows that most winds (73% of the year) are more than 4 mph and less than 24 mph. The wind is less than 4 mph for only 12% of the time and more than 39 mph (gale force 8) for 92 hours, or 1% of the time.

Distribution of hourly wind speed on Anglesey 1981-90.

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Days with Gales

The number of days with gales (mean wind speed >39 mph for at least 10 minutes) averages 30. Most gales occur in the months October to March. December and January have the most number with averages over 5. The least number of gales occur between April and July, all average less than 1. August has an average of 1 while September has an average of 2. The highest gust of 97 mph was recorded on 17 January 1965.

Number of days with gales on Anglesey 1961-90.


I am grateful to Robert Jones, Admin Officer at the Met Office at RAF Valley, for his help in finding some of the data.


Meteorological Office 1961-90. Monthly Weather Report: Annual Summaries. HMSO.

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Document dated: 15 October 2000. This page is maintained at

Copyright ©: 2000 Donald Perkins