Cardiff Weather: Your Complete Guide to Welsh Capital Climate
Understanding Cardiff's Maritime Climate
Cardiff sits on the Bristol Channel in South Wales, giving it a temperate maritime climate classified as Cfb under the Köppen climate classification system. The city experiences mild winters, cool summers, and substantial rainfall distributed throughout the year. Unlike continental climates with extreme temperature swings, Cardiff maintains relatively stable temperatures due to the moderating influence of the Atlantic Ocean and Irish Sea.
The city's weather patterns are heavily influenced by Atlantic weather systems that move eastward across the British Isles. These systems bring frequent cloud cover, precipitation, and moderate winds. Cardiff receives approximately 1,150mm (45 inches) of rainfall annually, which is actually less than many UK cities but still represents significant precipitation spread across 180-200 days per year. The wettest months typically occur from October through January, when Atlantic depressions are most active.
Temperature extremes are rare in Cardiff. The warmest temperature ever recorded was 33.3°C (91.9°F) in August 1990, while the coldest was -13.9°C (7.0°F) in January 1982. These records, spanning over four decades, demonstrate the city's generally moderate climate. Daily temperature ranges are also modest, typically varying by only 8-10°C between daytime highs and nighttime lows during most months.
| Month | Avg High (°C) | Avg Low (°C) | Rainfall (mm) | Rainy Days |
|---|---|---|---|---|
| January | 8 | 3 | 111 | 16 |
| February | 8 | 3 | 84 | 13 |
| March | 11 | 4 | 85 | 13 |
| April | 14 | 6 | 65 | 12 |
| May | 17 | 9 | 66 | 12 |
| June | 20 | 12 | 71 | 11 |
| July | 22 | 14 | 64 | 11 |
| August | 21 | 14 | 82 | 12 |
| September | 19 | 12 | 90 | 13 |
| October | 15 | 9 | 121 | 16 |
| November | 11 | 6 | 113 | 16 |
| December | 8 | 4 | 117 | 16 |
Seasonal Weather Patterns in Cardiff
Spring in Cardiff, spanning March through May, brings gradually warming temperatures and increasing daylight hours. March starts cool with average highs around 11°C (52°F), but by May temperatures reach a pleasant 17°C (63°F). This season sees moderate rainfall averaging 65-85mm per month, making it one of the drier periods. Spring weather can be quite variable, with sunny days alternating with rainy spells. The countryside around Cardiff becomes particularly green during this time, and daffodils bloom abundantly throughout Wales, the national flower appearing in parks and gardens across the city.
Summer months from June through August offer Cardiff's warmest and most stable weather. Average high temperatures range from 20-22°C (68-72°F), though occasional warm spells can push temperatures into the mid-20s Celsius. July typically provides the most sunshine, averaging around 200 hours of bright sunshine for the month. Despite being the warmest season, summer still sees regular rainfall with 64-82mm monthly, though rain tends to come in shorter bursts rather than prolonged periods. Coastal breezes keep conditions comfortable, and the extended daylight hours in June and July provide excellent conditions for outdoor activities around Cardiff Bay and nearby beaches.
Autumn arrives in September with temperatures still relatively mild at 19°C (66°F), but October sees a noticeable cooling to 15°C (59°F). This season marks the transition to wetter weather, with October and November each receiving over 110mm of rainfall. Atlantic storms become more frequent, bringing stronger winds and more persistent rain. By November, average highs drop to 11°C (52°F), and the city experiences significantly reduced daylight hours. Winter, from December through February, is Cardiff's coldest season but remains mild by global standards. Average highs hover around 8°C (46°F) with lows around 3-4°C (37-39°F). Snow is infrequent, typically occurring only 3-5 days per year and rarely accumulating significantly. December and January are the wettest months, each receiving approximately 111-117mm of precipitation.
Wind Patterns and Coastal Influences
Cardiff's position on the Bristol Channel exposes it to prevailing southwesterly winds that dominate throughout the year. Average wind speeds range from 10-15 mph, but coastal areas and elevated positions experience stronger gusts. The UK Met Office weather station at Cardiff Airport, located approximately 12 miles southwest of the city center, records some of the most reliable wind data for the region. Winter months see the strongest winds, with average speeds increasing to 15-18 mph and gusts frequently exceeding 30-40 mph during storm systems.
The Bristol Channel itself creates a funneling effect that can intensify winds, particularly during low-pressure systems tracking across the Atlantic. This geographical feature makes Cardiff windier than many inland UK cities. The channel's tidal range is among the largest in the world, reaching up to 14 meters (46 feet) during spring tides, second only to the Bay of Fundy in Canada. While tidal range doesn't directly affect wind patterns, it reflects the powerful marine forces at work in this coastal environment.
Wind direction varies seasonally, with southwesterly and westerly winds predominant from October through March, bringing mild, moist air from the Atlantic. Summer months see more variable wind directions, including easterly flows that can bring drier, warmer continental air from Europe. According to data from the UK Met Office, calm conditions (wind speeds below 2 mph) occur only about 5-8% of the time in Cardiff, reflecting its consistently breezy nature. Understanding these wind patterns is essential for planning outdoor activities, particularly sailing in Cardiff Bay or hiking in the nearby Brecon Beacons National Park.
| Season | Average Speed | Common Gusts | Prevailing Direction | Calm Days (%) |
|---|---|---|---|---|
| Winter (Dec-Feb) | 15-18 | 30-45 | Southwest | 5 |
| Spring (Mar-May) | 12-15 | 25-35 | West/Southwest | 7 |
| Summer (Jun-Aug) | 10-13 | 20-30 | Variable | 8 |
| Autumn (Sep-Nov) | 13-16 | 28-40 | Southwest | 6 |
Comparing Cardiff Weather to Other UK Cities
Cardiff's weather differs notably from other major UK cities due to its western coastal location. Compared to London, Cardiff receives about 150mm more annual rainfall (1,150mm vs 1,000mm), but experiences milder winter temperatures due to maritime influences. London's more continental position leads to colder winters with average January lows around 2°C compared to Cardiff's 3°C, and occasionally warmer summers with July highs reaching 24°C versus Cardiff's 22°C.
Manchester, located in northwest England, receives significantly more rainfall than Cardiff, averaging approximately 1,400mm annually. However, Manchester's temperatures are comparable to Cardiff's, both cities benefiting from Atlantic maritime influences. Edinburgh, Scotland's capital, is notably cooler year-round, with July highs averaging only 19°C compared to Cardiff's 22°C, and winter temperatures regularly dropping below freezing. Edinburgh also experiences more snowfall, typically 15-20 days annually versus Cardiff's 3-5 days.
Belfast, across the Irish Sea, shares many similarities with Cardiff due to comparable maritime exposure. Both cities average around 1,150-1,200mm annual rainfall and experience similar temperature ranges. However, Belfast tends to be slightly cooler in summer and experiences more frequent frost in winter. According to climate data compiled by the UK Met Office and published through their historical datasets, Cardiff ranks as the eleventh-wettest major UK city but maintains one of the mildest temperature profiles, rarely experiencing the temperature extremes seen in more inland or northern locations.