Carmarthen weather

The Carmarthen weather guide shows monthly weather averages (including daytime and night-time temperatures, rainfall and hours of sunshine) for holidays in Carmarthen, Carmarthenshire, Wales in 2026/2027.

• Carmarthen weather averages
• Carmarthen weather by month
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Carmarthen weather averages

Check the Carmarthen weather averages for each month of the year including maximum daytime and minimum night-time temperatures, monthly rainfall, number of days with rain and average daily hours of sunshine for Carmarthen, Carmarthenshire, Wales.

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Carmarthen weather by month

Check the weather for Carmarthen, Carmarthenshire, Wales for a particular month by selecting from the list below. This gives the best indication of what to expect from the weather months in advance.

• January
• February
• March
• April
• May
• June
• July
• August
• September
• October
• November
• December

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Carmarthen weather in January

The average maximum daytime temperature in Carmarthen in January is a cold 7°C (45°F), while the average minimum night-time temperature is a cold 2°C (36°F). You can expect on average 2 hours of sunshine a day in Carmarthen during January.

• 7
  7°C max day temperature
• 2
  2 hours of sunshine per day
• 20
  20 days with some rainfall
• 2
  2°C min night temperature
• 161
  161 mm of monthly rainfall

On average 161 mm (6.3 inches) of rain normally falls in Carmarthen during January with rain falling on 20 days of the month.

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Carmarthen weather in February

The average maximum daytime temperature in Carmarthen in February is a cool 8°C (46°F), while the average minimum night-time temperature is a cold 2°C (36°F). You can expect on average 3 hours of sunshine a day in Carmarthen during February.

• 8
  8°C max day temperature
• 3
  3 hours of sunshine per day
• 16
  16 days with some rainfall
• 2
  2°C min night temperature
• 112
  112 mm of monthly rainfall

On average 112 mm (4.4 inches) of rain normally falls in Carmarthen during February with rain falling on 16 days of the month.

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Carmarthen weather in March

The average maximum daytime temperature in Carmarthen in March is a cool 9°C (48°F), while the average minimum night-time temperature is a cold 3°C (37°F). You can expect on average 4 hours of sunshine a day in Carmarthen during March.

• 9
  9°C max day temperature
• 4
  4 hours of sunshine per day
• 17
  17 days with some rainfall
• 3
  3°C min night temperature
• 114
  114 mm of monthly rainfall

On average 114 mm (4.5 inches) of rain normally falls in Carmarthen during March with rain falling on 17 days of the month.

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Carmarthen weather in April

The average maximum daytime temperature in Carmarthen in April is a cool 12°C (54°F), while the average minimum night-time temperature is a cold 4°C (39°F). You can expect on average 5 hours of sunshine a day in Carmarthen during April.

• 12
  12°C max day temperature
• 5
  5 hours of sunshine per day
• 14
  14 days with some rainfall
• 4
  4°C min night temperature
• 84
  84 mm of monthly rainfall

On average 84 mm (3.3 inches) of rain normally falls in Carmarthen during April with rain falling on 14 days of the month.

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Carmarthen weather in May

The average maximum daytime temperature in Carmarthen in May is a comfortable 15°C (59°F), while the average minimum night-time temperature is a cold 7°C (45°F). You can expect on average 6 hours of sunshine a day in Carmarthen during May.

• 15
  15°C max day temperature
• 6
  6 hours of sunshine per day
• 13
  13 days with some rainfall
• 7
  7°C min night temperature
• 79
  79 mm of monthly rainfall

On average 79 mm (3.1 inches) of rain normally falls in Carmarthen during May with rain falling on 13 days of the month.

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Carmarthen weather in June

The average maximum daytime temperature in Carmarthen in June is a comfortable 17°C (63°F), while the average minimum night-time temperature is a cool 10°C (50°F). You can expect on average 6 hours of sunshine a day in Carmarthen during June.

• 17
  17°C max day temperature
• 6
  6 hours of sunshine per day
• 14
  14 days with some rainfall
• 10
  10°C min night temperature
• 97
  97 mm of monthly rainfall

On average 97 mm (3.8 inches) of rain normally falls in Carmarthen during June with rain falling on 14 days of the month.

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Carmarthen weather in July

The average maximum daytime temperature in Carmarthen in July is a comfortable 20°C (68°F), while the average minimum night-time temperature is a cool 12°C (54°F). You can expect on average 6 hours of sunshine a day in Carmarthen during July.

• 20
  20°C max day temperature
• 6
  6 hours of sunshine per day
• 13
  13 days with some rainfall
• 12
  12°C min night temperature
• 86
  86 mm of monthly rainfall

On average 86 mm (3.4 inches) of rain normally falls in Carmarthen during July with rain falling on 13 days of the month.

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Carmarthen weather in August

The average maximum daytime temperature in Carmarthen in August is a comfortable 19°C (66°F), while the average minimum night-time temperature is a cool 12°C (54°F). You can expect on average 6 hours of sunshine a day in Carmarthen during August.

• 19
  19°C max day temperature
• 6
  6 hours of sunshine per day
• 15
  15 days with some rainfall
• 12
  12°C min night temperature
• 124
  124 mm of monthly rainfall

On average 124 mm (4.9 inches) of rain normally falls in Carmarthen during August with rain falling on 15 days of the month.

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Carmarthen weather in September

The average maximum daytime temperature in Carmarthen in September is a comfortable 17°C (63°F), while the average minimum night-time temperature is a cool 10°C (50°F). You can expect on average 4 hours of sunshine a day in Carmarthen during September.

• 17
  17°C max day temperature
• 4
  4 hours of sunshine per day
• 16
  16 days with some rainfall
• 10
  10°C min night temperature
• 131
  131 mm of monthly rainfall

On average 131 mm (5.2 inches) of rain normally falls in Carmarthen during September with rain falling on 16 days of the month.

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Carmarthen weather in October

The average maximum daytime temperature in Carmarthen in October is a comfortable 14°C (57°F), while the average minimum night-time temperature is a cool 8°C (46°F). You can expect on average 3 hours of sunshine a day in Carmarthen during October.

• 14
  14°C max day temperature
• 3
  3 hours of sunshine per day
• 19
  19 days with some rainfall
• 8
  8°C min night temperature
• 157
  157 mm of monthly rainfall

On average 157 mm (6.2 inches) of rain normally falls in Carmarthen during October with rain falling on 19 days of the month.

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Carmarthen weather in November

The average maximum daytime temperature in Carmarthen in November is a cool 10°C (50°F), while the average minimum night-time temperature is a cold 4°C (39°F). You can expect on average 2 hours of sunshine a day in Carmarthen during November.

• 10
  10°C max day temperature
• 2
  2 hours of sunshine per day
• 20
  20 days with some rainfall
• 4
  4°C min night temperature
• 167
  167 mm of monthly rainfall

On average 167 mm (6.6 inches) of rain normally falls in Carmarthen during November with rain falling on 20 days of the month.

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Carmarthen weather in December

The average maximum daytime temperature in Carmarthen in December is a cool 8°C (46°F), while the average minimum night-time temperature is a cold 3°C (37°F). You can expect on average 1 hours of sunshine a day in Carmarthen during December.

• 8
  8°C max day temperature
• 1
  1 hour of sunshine per day
• 20
  20 days with some rainfall
• 3
  3°C min night temperature
• 169
  169 mm of monthly rainfall

On average 169 mm (6.7 inches) of rain normally falls in Carmarthen during December with rain falling on 20 days of the month.

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