Merthyr Tydfil — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Merthyr Tydfil, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Merthyr Tydfil today is 18.4°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| AUG 6 | 17.7°C | 19.0°C | |
| AUG 7 | 17.7°C | 19.0°C | |
| AUG 8 | 17.7°C | 19.0°C | |
| AUG 9 | 17.7°C | 19.0°C | |
| AUG 10 | 18.4°C | 19.0°C | |
| AUG 11 | 18.4°C | 19.0°C | |
| AUG 12 | 18.4°C | 19.0°C | |
| AUG 13 | 18.4°C | 19.0°C | |
| AUG 14 | 19.0°C | 18.4°C | |
| AUG 15 | 19.0°C | 18.5°C | |
| AUG 16 | 19.0°C | 18.5°C | |
| AUG 17 | 19.0°C | 18.5°C | |
| AUG 18 | 19.0°C | 18.6°C | |
| AUG 19 | 19.0°C | 18.6°C | |
| AUG 20 | 19.0°C | 18.6°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 2°C | 6°C | 9°C |
| February | 3°C | 7°C | 9°C |
| March | 5°C | 9°C | 11°C |
| April | 6°C | 10°C | 14°C |
| May | 8°C | 14°C | 18°C |
| June | 10°C | 17°C | 24°C |
| July | 13°C | 19°C | 25°C |
| August | 15°C | 19°C | 24°C |
| September | 13°C | 18°C | 22°C |
| October | 9°C | 13°C | 16°C |
| November | 4°C | 8°C | 11°C |
| December | 3°C | 7°C | 9°C |
Merthyr Tydfil: Weather Forecast
August 14
August 15
August 16
August 17
August 18
August 19
Location & Local Information
Merthyr Tydfil lies in the upper valley of the River Taff, where the river begins its journey south from the Brecon Beacons. At this higher elevation, the water is notably cooler than in the lowlands. During winter, the River Taff near Merthyr typically averages 3–5 °C (37–41 °F), while spring brings a gradual rise to around 8–10 °C (46–50 °F). In summer, the water can warm to about 14–16 °C (57–61 °F) in slower, sunlit sections, though mountain-fed streams often keep it brisk even on warm days. By autumn, the temperature usually drops back to around 9–11 °C (48–52 °F), following the pattern of shorter daylight and cooler air.
Swimming in the River Taff around Merthyr Tydfil is possible and increasingly popular among wild swimming enthusiasts, but it remains best suited for confident swimmers familiar with natural conditions. The upper stretches are clean and clear, though currents can be swift after rainfall. Calm pools near Cefn Coed and within the Brecon Beacons National Park offer safer spots for a dip, particularly in midsummer. Wetsuits are advisable outside the warmest months. The area around Merthyr also provides scenic walking and cycling routes, with nearby attractions including Pontsticill Reservoir, Cyfarthfa Castle, and the dramatic landscapes of Pen y Fan.