"If you can see the Mumbles Head clearly, it is going to rain; if you can't, it is raining."
- local weather forecasting joke.
The homogeneity of climate records of Swansea and Gower have been slightly disturbed due to the shifting location of its weather stations and the varying methods employed in the collection and the recording of its data.
From 1886 to 1905 it was the Swansea Harbour Trust who were responsible for the collating and archiving of climatology records. There are, however, no details available as to the methodology they employed in the gathering of this information and the official metreological record for Swansea does not commence until 1908 when a weather station was built at Victoria Park, Swansea.
A second station was established at Mumbles Head in 1959. More inland, most of Gower’s recorded climatology data derives from rainfall measurements recorded between 1928 and 1960 at Penrice.
An amateur meteorologist of Penmaen, Gower, recorded weather data from 1961-2009. John Powell had provided daily data to the Met Office from his one-man weather station for almost 50 years. There is also a climate/environmental station in Swansea's city centre.
Earlier records are more sporadic and less detailed in their recording of precise data. In 1839, local surgeon J. W. Gutch published a general précis on the area’s climate in his work 'Medical Topography, Statistics, Climatology and Natural History of Swansea' where he stated that:
“The climate of Swansea is generally mild and a long continuance of cold weather of rare occurrence. It is, however, certainly humid owing perhaps to the district being exposed to vapours caused by western or south-western winds from the Atlantic and attracted by the hills; these winds prevailing to a very considerable extent.
The humidity is a source of much perplexity to the farmer during the hay and corn harvest and also causes considerable damage to various agricultural crops by the abundant growth of natural gasses which in consequence spring up, and which in the deep gravelly soils it is found almost impossible to eradicate from the arable lands.”
The surgeon later became both editor and treasurer of the British Meteorological Society in London.
The area was generally thought of as possessing a healthy climate, despite the nearby copper smelting works that poisoned so much of the nearby land and air. John Jenkins, keeping brief climate records at The Royal Institution of South Wales between 1843 and 1846 concluded that the climate here was:
“highly conductive to the health of persons affected with pulmonary complaints and desirable for the residence of the valetudinarian.”
One of the major catalysts to Swansea and Gower’s climate is the Bristol Channel which affords the good passage of air from the south-west. Sea temperatures here range from an average of 9° C in February to 17° C in July and provide a great influence to the air temperature of much of the peninsula.
Protected from colder northern influences by both the coalfield plateau and high scarp of the Carmarthen Fans plus the huge hill ranges of the Brecon Beacons, the area here experiences many of the qualities associated with a west coast Oceanic climate.
Moderated by such oceanic influences, Swansea and Gower avoid most extremes of heat or cold that can occur elsewhere in the U.K. Demonstrating this fact, Swansea’s lowest recorded temperature was recorded as -10.0° C on January 26th 1945. That same night, Cardiff felt the brunt of a -16.7° C chill. John Powell of Penmaen also reported a record low temperature of -10.0° C on January 13, 1987.
|Mumbles Head climate station:|
Location: 51.565, -3.981
Altitude: 32 m above mean sea level
|Averages per month|
|Days of air frost |
|Days of rainfall >= 1 mm |
Sunshine and Rainfall
Swansea and Gower are known to suffer many days of total cloud cover, with the cloud base falling below 600 metres on many of these occasions. This has often led to the impression that the area suffers from a particularly dark and rainy disposition. However, such blanketing cloud conditions can often lead to little or no rainfall over the city and the peninsula and the region as a whole achieves rather a good proportion of recorded sunshine in comparison with the rest of the U.K.
Swansea also experiences far fewer mists and fogs than other area and when such conditions are produced, they are formed from sea-mists rather than the cooling of radiation in clear weather. Such sea-mists are inherently less dense than the radiation mists produced over many other parts of the country and reduce light and visibility to a much lesser degree.
Records of sunshine and rainfall may prove of particular interest to tourists when planning a visit to the locale. For example, whilst holidaymaker numbers on the peninsula reach a peak in August, this figure does not correspond to the area’s most complimenting weather. May and June usually record the area's greatest hours of sunshine whilst July and August are frequently known to exhibit more unstable meteorological conditions. That stated, July and August usually average the warmest, if not the sunniest, months of the year.
Onshore winds, warmed from coastal tides, plus its geological protection from northerly influences on the climate combine to produce little snowfall over Swansea and Gower. On average, snow is only likely to fall on only six days per annum, chiefly contained in the first two months of the year.
When snow does fall, it seldom establishes ground cover and when it does fall thick enough and long enough for it to settle, it lasts no longer than a day or two.