 |
|
| Weather |
|
Live Wind Web Cams |
How Windy is Wellington? - Article compiled by James Court
We wanted to find out exactly how windy Wellington is and when it is windy. What is presented here is a gathering together of available information that better defines Wellington's wind climate in a form understandable to wind junkies. We all know that Wellington is pretty windy, but not many of us know exactly how windy. It's easy to find detailed statistics on sunshine hours, rainfall and temperature however, wind speed statistics and information are harder to find. How do you know for sure which month is the windiest, was last year windier than the previous year, etc, etc. This is important and interesting information for any wind sports enthusiast to be able to compare with experience or decide which month to take annual leave. Wellington wind summary: • Wellington is located in a River of Wind - a wind corridor between the South Island and the North Island. • Wellington is the windiest main centre in New Zealand with a mean annual wind speed of 22 km/h. • Wellington also has an average of 22 days per year with mean wind speeds over 63 km/h (40 knots). • Wellington averages 173 days a year with wind gusts greater than about 60 km/h or 32 knots. • October is generally the windiest month of the year with a mean of 27 days with wind speeds over 15 knots, 19 of those days are over 20 knots. • North is by far the most common wind direction, blowing from this direction (0 degrees) a massive 37.6% of the time. • Wellington is one of the windiest cities in the world (possibly the windiest) and is windier than other southern windy cities including Cape Town, Perth, and Geraldton. • The strongest wind speeds where recorded at Hawkins Hill of 248km/h (134 knots) on the 6 November 1959 and 4 July 1962. Rivers of wind Wellington is located next to Cook Strait, which forms a narrow gap between the mountain ranges of the North and South Islands. This gap between the islands and mountain ranges accelerates the wind through the Cook Strait making Wellington a very windy city. Wellingtons physical wind climate is best described in an article written by Metservice head forecaster at the time Bob McDavitt for NZ Windsurfer magazine in 1995 titled "Rivers of Wind". McDavitt describes what Rivers of Wind are: "These occur over the sea at the downwind end of a long range of mountains. These rivers are strongest when there is a HIGH on the weather map and isobars are drawn across the mountains. The wind can not follow the isobars through the mountains, and a HIGH may restrict airflow up and over the mountains, so that a lot of the air that collects up-wind of the mountain chain can only exit around the ends or through the gaps . . . and this wind blows best once it reaches the open sea. . . . Wellington is located next door to Cook Strait and is a perfect example of wind galloping through the gaps." McDavitt also compares wind statistics between New Zealand main centres, showing their mean wind speed km/hr and number of days with wind speeds over gale force (63km/h) between 1971 and 2000. Figure 1 shows that Wellington tops the mean wind speed comparisons with the notable exception of the Chatham Islands and ranks number 3 behind Kaikoura and Scott Base for the number of gale force days. Figure 1 New Zealand Wind Statistics 1971 - 2000 Source: NZ Metservice
We have analysed the Metservice data to determine:
The raw Metservice data is for Wellington Airport between 1995 and 2001. The Wellington Airport site was selected as it is the closest Metservice weather station and considered representative of most of the main Wellington City sailing spots particularly Lyall Bay, Evans Bay and Seatoun. • So when is it windy?Figure 2 shows the mean number of days per month wind speeds at the Wellington airport that exceed 15 knots and 20 knots for at least one hour per day. A mean of 15 knots was selected as the minimum amount of wind required for most sailors to have a reasonable light wind sail, the 20 knot threshold was selected to identify higher wind conditions.
October is the windiest month of the year with a mean 27 days of wind speeds over 15 knots, 19 of those days are over 20 knots. July is the least windy month with a mean of 21 days with wind speeds over 15 knots, 12 of those days are over 20 knots. October to January is the windiest time of year with the least windy months extending from February to July. Figure 3 Wellington average wind speed per month
Source: http://www.mytravelguide.com/travel-tools/climate-graphs/ This graph sourced from My travel guide climate graphs and shows the breakdown of average wind speeds per month. The location of the monitoring station is unknown. Which direction does it blow from?To determine which direction the wind blows from, the direction of wind speeds over 15 knots and 20 knots was determined. The figure below shows this distribution on a radar graph (similar to a wind rose).
The funnelling and redirecting effects of the Cook Strait can be seen strongly in the above graph. Northerlies are the most common a massive 37.6% of the time, the next closest frequency direction is from the South at 13.1%. Westerly (WNW, W, WSW) and Easterly (ENE, E, ESE) wind directions are not represented at all. Higher wind speeds over 20 knots (blue) show a similar distribution. The bias to direct Northerly and Southerly wind directions is probably slightly exaggerated by the North South alignment of the hills surrounding the airport. Metservice lead forecaster Erick Brenstrum in an article for NZ National Geographic describes this effect. "On average, northerlies outnumber southerlies about two to one through Cook Strait. This is because Cook Strait lies in a latitude where westerly winds predominate, but the westerlies are deflected by the mountains to blow north or north-west through the Strait." Source: www.metservice.co.nz How strong does it get? Wellington is not only known for its frequently windy conditions but for the strength of its wind. The Metservice reports the following extreme wind conditions in Wellington:
Source: www.metservice.co.nz How does Wellington compare to other windy cities The average windspeeds from other cities in the southern hemisphere known or reputed to be windy cities have been compiled and compared to Wellington using the My travel guide climate graphs. Figure 5, Monthly average wind speeds comparisons between Wellington, Cape Town, Geraldton, and Perth. |
Hosting sponsored by The Kiwi Web Hosting Company