Weather Program
The weather of Gough Island varies greatly with the change of seasons. The summers are relatively dry, with temperatures occasionally reaching 25ºC. Rainfall is erratic, with dry spells of up to seven or eight days, separated by days with rainfall of 30 to 40 mm, reaching as much as 100 mm in 24 hours. The winters on the other hand are characterized by continuous rainfall, with some days only a few mm and others averaging 15-20 mm. It is not uncommon to have one or two days per month with rainfall in excess of 60 mm. The months of June and July are characterized by continuous strong winds, often reaching gale force, 35 knots (65 km/h) average, with gusts of over 100 km/h.Meteorological station and personnel
The Gough Island weather station is considered to be one of the most important stations in the world. It is one of few weather stations in the Southern Atlantic Ocean. It helps to provide information of weather systems over the oceans surrounding South Africa - areas from where very little information is available.
According to the needs of the World Meteorological Organisation the South African weather service manage two fully manned island weather stations; Gough and Marion Islands. We have automatic weather stations on Tristan da Cunha, SANAE (Antarctica), Southern Thule and Zavadovski Islands, and 30-40 drifting weather buoys are deployed annually.
SA Agulhas Weather Office
As soon as the ship leaves Cape Town, the met team start with three hourly weather observations and this is kept up for the duration of the voyage. Because of the drift pattern of the weather buoys a few are deployed on the way, with others deployed on voyages to Marion and Antarctica.Gough Island Weather Station
In many ways the weather station on Gough functions just like any other weather office in South Africa.Meteorologists do hourly surface observations which are augmented by an automatic weather station which records data every five minutes. Elements recorded are temperature, rainfall, sunshine, radiation, wind speed, wind direction, barometric pressure, humidity and sea surface temperatures. Visual observations include cloud identification and weather conditions. Upper air soundings are done twice a day to determine temperature, pressure, humidity, winds speed and wind direction up to 30 000 metres. A LUT on the island receives data from drifting weather buoys within a radius of up to 3000 km. The buoy data is transmitted to Pretoria and used in weather forecasting. This happens 4-6 times a day - depending on satellite passes. Meteorological observations are coded and transmitted to the central forecasting office in Pretoria immediately after the observation. From Pretoria it is made internationally available on the Global Telecommunications System. Extremes and averages are transmitted to Pretoria on a monthly basis.
Weather forecasting
All forecasting is done by the Central Forecasting Office (CFO) in Pretoria and not on the island. CFO can give dedicated forecasts for Gough by request.Climate recearch
Meteorological data from Gough is also used for climatological research. Because the station has been in operation for such a long time in an almost unchanged condition, and without unnatural influences, it has become most valuable in determining long term climatological tendencies.
