Merthyr Tydfil weather in May

In May, Merthyr Tydfil sees average daytime highs of 14°C and overnight lows near 7°C, with 90 mm of rain across 14.2 wet days and about 15.4 hours of daylight. It is the 5th-warmest and 6th-wettest month of the year here.

Highs climb over the month, from about 13°C in the first days to 16°C by the end. The sky is clear or mostly clear about 12% of the time in May, and the air most often feels dry.

Daylight stretches from about 14 h 36 min at the start of May to 16 hours by month's end. Set against the rest of the year, May is Merthyr Tydfil's 3rd-clearest and 8th-windiest month. For the whole year in context, see Merthyr Tydfil's year-round climate.

Daytime high: 14°; 5th warmest
Overnight low: 7°; 7th coldest
Rainfall: 90 mm; 14.2 wet days
Daylight: 15 h 24 min; 4:28 AM – 7:52 PM
Cloud cover: 72%; 3rd clearest
Wind: 14 km/h; 8th windiest
Solar energy: 5.12 kWh/m²
Travel score: 3.7; out of 10

Merthyr Tydfil is town in Wales.

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← April Merthyr Tydfil year-round climate June →Best places to visit in May

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 13°C in the first days to 16°C by the end.

A typical May day in Merthyr Tydfil reaches about 14°C in the afternoon and slips back to 7°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 11°C and 19°C. Set against its neighbours, May runs about 3°C warmer than April and about 3°C cooler than June.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Avg high (°C)	13	13	13	13	13	13	13	14	14	14	14	14	14	14	14	14	14	15	15	15	15	15	15	15	15	15	16	16	16	16	16
Avg low (°C)	6	6	6	6	6	6	6	6	6	7	7	7	7	7	7	7	7	7	7	8	8	8	8	8	8	8	8	8	9	9	9

	Avg high (°C)	Avg low (°C)
1	13	6
2	13	6
3	13	6
4	13	6
5	13	6
6	13	6
7	13	6
8	14	6
9	14	6
10	14	7
11	14	7
12	14	7
13	14	7
14	14	7
15	14	7
16	14	7
17	14	7
18	15	7
19	15	7
20	15	8
21	15	8
22	15	8
23	15	8
24	15	8
25	15	8
26	15	8
27	16	8
28	16	8
29	16	9
30	16	9
31	16	9

How May really feels in Merthyr Tydfil

Once humidity and wind are folded in, May averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C

heat index over the day's high

Days feeling ≤ 0°C

wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Merthyr Tydfil weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 6th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	6° / 2°	112	15.3	1.7	8.1	0.6
Feb	7° / 2°	87	12	1.8	9.6	0.7
Mar	9° / 3°	80	13.3	1.3	11.5	1.5
Apr	11° / 4°	81	13.2	0.5	13.6	2.6
May	14° / 7°	90	14.2	0	15.4	3.7
Jun	17° / 10°	87	12.9	0	16.3	4.8
Jul	19° / 12°	89	14.3	0	16	5.3
Aug	18° / 12°	95	13.5	0	14.4	5.3
Sep	16° / 10°	83	11.7	0	12.4	4.7
Oct	13° / 7°	120	14.3	0.1	10.4	3.1
Nov	9° / 5°	114	15.2	0.6	8.6	1.7
Dec	7° / 3°	121	14.2	1.5	7.6	0.8

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 12% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 73%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Clearer (%)	30	30	30	29	29	29	29	29	29	28	27	27	26	26	26	26	25	25	26	25	25	25	25	26	26	26	27	27	27	27	29
Cloudier (%)	70	70	70	71	71	71	71	71	71	72	73	73	74	74	74	74	75	75	74	75	75	75	75	74	74	74	73	73	73	73	71

	Clearer (%)	Cloudier (%)
1	30	70
2	30	70
3	30	70
4	29	71
5	29	71
6	29	71
7	29	71
8	29	71
9	29	71
10	28	72
11	27	73
12	27	73
13	26	74
14	26	74
15	26	74
16	26	74
17	25	75
18	25	75
19	26	74
20	25	75
21	25	75
22	25	75
23	25	75
24	26	74
25	26	74
26	26	74
27	27	73
28	27	73
29	27	73
30	27	73
31	29	71

Chance of precipitation in May

Any precipitation

Merthyr Tydfil gets around 90 mm of rain over 14.2 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 47% and peaks near 48% on the wettest days.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Rain chance (%)	47	47	47	47	47	47	47	47	47	47	47	47	48	48	48	47	47	47	46	46	46	46	46	46	46	46	46	46	46	46	46

	Rain chance (%)
1	47
2	47
3	47
4	47
5	47
6	47
7	47
8	47
9	47
10	47
11	47
12	47
13	48
14	48
15	48
16	47
17	47
18	47
19	46
20	46
21	46
22	46
23	46
24	46
25	46
26	46
27	46
28	46
29	46
30	46
31	46

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 97% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Dry (%)	100	100	99	99	99	99	99	99	98	98	98	98	98	98	98	98	97	97	97	97	97	97	97	96	96	96	96	96	95	95	95
Comfortable (%)	0	0	1	1	1	1	1	1	2	2	2	2	2	2	2	2	3	3	3	3	3	3	3	4	4	4	4	4	5	5	5

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	99	1
4	99	1
5	99	1
6	99	1
7	99	1
8	99	1
9	98	2
10	98	2
11	98	2
12	98	2
13	98	2
14	98	2
15	98	2
16	98	2
17	97	3
18	97	3
19	97	3
20	97	3
21	97	3
22	97	3
23	97	3
24	96	4
25	96	4
26	96	4
27	96	4
28	96	4
29	95	5
30	95	5
31	95	5

Wind in May

Winds average 14 km/h in May.

Across May, daily wind ranges from about 13 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Wind speed (km/h)	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	13	13	13	13
Feels	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze

	Wind speed (km/h)	Feels
1	14	light breeze
2	14	light breeze
3	14	light breeze
4	14	light breeze
5	14	light breeze
6	14	light breeze
7	14	light breeze
8	14	light breeze
9	14	light breeze
10	14	light breeze
11	14	light breeze
12	14	light breeze
13	14	light breeze
14	14	light breeze
15	14	light breeze
16	14	light breeze
17	14	light breeze
18	14	light breeze
19	14	light breeze
20	14	light breeze
21	14	light breeze
22	14	light breeze
23	14	light breeze
24	14	light breeze
25	14	light breeze
26	14	light breeze
27	14	light breeze
28	13	light breeze
29	13	light breeze
30	13	light breeze
31	13	light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 14 h 36 min at the start of May to 16 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 84 minutes over May. Sunrise moves from 4:54 AM to 4:10 AM, and sunset from 7:27 PM to 8:12 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Daylight (h)	14.6	14.6	14.7	14.7	14.8	14.8	14.9	15.0	15.0	15.1	15.1	15.2	15.2	15.3	15.3	15.4	15.4	15.5	15.5	15.6	15.6	15.7	15.7	15.8	15.8	15.9	15.9	15.9	16.0	16.0	16.0
Sunrise (AM)	4:54	4:52	4:50	4:48	4:46	4:45	4:43	4:41	4:39	4:38	4:36	4:34	4:33	4:31	4:29	4:28	4:26	4:25	4:24	4:22	4:21	4:20	4:18	4:17	4:16	4:15	4:14	4:13	4:12	4:11	4:10
Sunset (PM)	7:27	7:29	7:31	7:32	7:34	7:36	7:37	7:39	7:41	7:42	7:44	7:45	7:47	7:49	7:50	7:52	7:53	7:55	7:56	7:58	7:59	8:00	8:02	8:03	8:05	8:06	8:07	8:09	8:10	8:11	8:12

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	14.6	4:54	7:27
2	14.6	4:52	7:29
3	14.7	4:50	7:31
4	14.7	4:48	7:32
5	14.8	4:46	7:34
6	14.8	4:45	7:36
7	14.9	4:43	7:37
8	15.0	4:41	7:39
9	15.0	4:39	7:41
10	15.1	4:38	7:42
11	15.1	4:36	7:44
12	15.2	4:34	7:45
13	15.2	4:33	7:47
14	15.3	4:31	7:49
15	15.3	4:29	7:50
16	15.4	4:28	7:52
17	15.4	4:26	7:53
18	15.5	4:25	7:55
19	15.5	4:24	7:56
20	15.6	4:22	7:58
21	15.6	4:21	7:59
22	15.7	4:20	8:00
23	15.7	4:18	8:02
24	15.8	4:17	8:03
25	15.8	4:16	8:05
26	15.9	4:15	8:06
27	15.9	4:14	8:07
28	15.9	4:13	8:09
29	16.0	4:12	8:10
30	16.0	4:11	8:11
31	16.0	4:10	8:12

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.12 kWh/m².

For context, solar energy here swings from a low near 0.64 kWh/m² to a high of 5.39 kWh/m² in June across the year — May's 5.12 kWh/m² sits near the top of that range.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Solar energy (kWh/m²)	4.8	4.8	4.9	4.9	4.9	5.0	5.0	5.0	5.0	5.0	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.2	5.2	5.2	5.2	5.2	5.2	5.2	5.2
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright

	Solar energy (kWh/m²)	Level
1	4.8	Bright
2	4.8	Bright
3	4.9	Bright
4	4.9	Bright
5	4.9	Bright
6	5.0	Bright
7	5.0	Bright
8	5.0	Bright
9	5.0	Bright
10	5.0	Bright
11	5.1	Bright
12	5.1	Bright
13	5.1	Bright
14	5.1	Bright
15	5.1	Bright
16	5.1	Bright
17	5.1	Bright
18	5.1	Bright
19	5.1	Bright
20	5.1	Bright
21	5.1	Bright
22	5.1	Bright
23	5.1	Bright
24	5.2	Bright
25	5.2	Bright
26	5.2	Bright
27	5.2	Bright
28	5.2	Bright
29	5.2	Bright
30	5.2	Bright
31	5.2	Bright

Planning a trip in May

Is May a good time to visit Merthyr Tydfil?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

3.7

Sightseeing

5th-best month of the year

0.1

Beach & pool

5th-best month of the year

May is a weaker month for outdoor sightseeing in Merthyr Tydfil.

What to pack for Merthyr Tydfil in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Merthyr Tydfil sees daytime highs around 14°C and nights near 7°C. Pack rain gear. Worth having: a warm layer and sun protection. About 14 days see rain.

rain geara warm layersun protection

Sea temperature near Merthyr Tydfil in May

The nearest coast averages about 11°C in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 37 km away) is warmest in August at about 18°C and coldest in February near 8°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sea temperature (°C)	8	8	8	9	11	14	16	18	17	15	12	10
Comfort	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Cool	Cool	Cool	Cool	Bracing	Bracing

	Sea temperature (°C)	Comfort
Jan	8	Bracing
Feb	8	Bracing
Mar	8	Bracing
Apr	9	Bracing
May	11	Bracing
Jun	14	Bracing
Jul	16	Cool
Aug	18	Cool
Sep	17	Cool
Oct	15	Cool
Nov	12	Bracing
Dec	10	Bracing

UV index in Merthyr Tydfil in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Merthyr Tydfil peaks around August 13 at about 6 (high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near January 1 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 6 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	1	1	3	4	6	6	6	7	4	2	1	1
Level	Low	Low	Moderate	Moderate	High	High	High	High	Moderate	Moderate	Low	Low

	UV index (midday)	Level
Jan	1	Low
Feb	1	Low
Mar	3	Moderate
Apr	4	Moderate
May	6	High
Jun	6	High
Jul	6	High
Aug	7	High
Sep	4	Moderate
Oct	2	Moderate
Nov	1	Low
Dec	1	Low

Location & terrain

Where is Merthyr Tydfil?

Merthyr Tydfil sits at 51.7°N, 3.4°W, 186 m above sea level, in United Kingdom. The nearest listed city is Aberdare, 6.0 km away.

Topography around Merthyr Tydfil

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Merthyr Tydfil.

Within 3 km, the terrain around Merthyr Tydfil has significant variations in elevation — a maximum elevation change of 328 m around an average of 280 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 818 m; within 80 km, large variations in elevation — a maximum elevation change of 864 m.

The land around Merthyr Tydfil is covered by trees (41%), grassland (33%) and artificial surfaces (23%) within 3 km, grassland (58%) and trees (34%) within 16 km, and grassland (53%) within 80 km.

3 km

328 m

trees 41%

16 km

818 m

grassland 58%

80 km

864 m

grassland 53%

treesgrasslandcroplandartificial surfacesbare terrainwater

← April Merthyr Tydfil year-round climate June →Best places to visit in May

May weather nearby: Aberdare 6.0 km · Rhondda 11 km · Ebbw Vale 12 km · Gelligaer 13 km · Blackwood 15 km · Tonypandy 15 km · Pontypridd 16 km · Caerphilly 22 km

United Kingdom travel facts

Travel advisory: Level 2; Exercise Increased Caution
Power plugs: Type D / G / M; 230 V · 50 Hz
Prices: ≈ 89% of US; price level, 2025
GDP per capita: $57,602; 2025
Happiness: 6.7 / 10; World Happiness, 2025
Safe drinking water: 100%; of population, 2024
Homicide rate: 1.1; per 100k, 2021
Road deaths: 3.2; per 100k/yr, 2019
Income group: High; World Bank
Religion

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Merthyr Tydfil (51.7479°, -3.3778°, elevation 186 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).

	Avg high (°C)	Avg low (°C)
1	13	6
2	13	6
3	13	6
4	13	6
5	13	6
6	13	6
7	13	6
8	14	6
9	14	6
10	14	7
11	14	7
12	14	7
13	14	7
14	14	7
15	14	7
16	14	7
17	14	7
18	15	7
19	15	7
20	15	8
21	15	8
22	15	8
23	15	8
24	15	8
25	15	8
26	15	8
27	16	8
28	16	8
29	16	9
30	16	9
31	16	9

	Clearer (%)	Cloudier (%)
1	30	70
2	30	70
3	30	70
4	29	71
5	29	71
6	29	71
7	29	71
8	29	71
9	29	71
10	28	72
11	27	73
12	27	73
13	26	74
14	26	74
15	26	74
16	26	74
17	25	75
18	25	75
19	26	74
20	25	75
21	25	75
22	25	75
23	25	75
24	26	74
25	26	74
26	26	74
27	27	73
28	27	73
29	27	73
30	27	73
31	29	71

	Rain chance (%)
1	47
2	47
3	47
4	47
5	47
6	47
7	47
8	47
9	47
10	47
11	47
12	47
13	48
14	48
15	48
16	47
17	47
18	47
19	46
20	46
21	46
22	46
23	46
24	46
25	46
26	46
27	46
28	46
29	46
30	46
31	46

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	99	1
4	99	1
5	99	1
6	99	1
7	99	1
8	99	1
9	98	2
10	98	2
11	98	2
12	98	2
13	98	2
14	98	2
15	98	2
16	98	2
17	97	3
18	97	3
19	97	3
20	97	3
21	97	3
22	97	3
23	97	3
24	96	4
25	96	4
26	96	4
27	96	4
28	96	4
29	95	5
30	95	5
31	95	5

	Avg high (°C)	Avg low (°C)
1	13	6
2	13	6
3	13	6
4	13	6
5	13	6
6	13	6
7	13	6
8	14	6
9	14	6
10	14	7
11	14	7
12	14	7
13	14	7
14	14	7
15	14	7
16	14	7
17	14	7
18	15	7
19	15	7
20	15	8
21	15	8
22	15	8
23	15	8
24	15	8
25	15	8
26	15	8
27	16	8
28	16	8
29	16	9
30	16	9
31	16	9

	Clearer (%)	Cloudier (%)
1	30	70
2	30	70
3	30	70
4	29	71
5	29	71
6	29	71
7	29	71
8	29	71
9	29	71
10	28	72
11	27	73
12	27	73
13	26	74
14	26	74
15	26	74
16	26	74
17	25	75
18	25	75
19	26	74
20	25	75
21	25	75
22	25	75
23	25	75
24	26	74
25	26	74
26	26	74
27	27	73
28	27	73
29	27	73
30	27	73
31	29	71

	Rain chance (%)
1	47
2	47
3	47
4	47
5	47
6	47
7	47
8	47
9	47
10	47
11	47
12	47
13	48
14	48
15	48
16	47
17	47
18	47
19	46
20	46
21	46
22	46
23	46
24	46
25	46
26	46
27	46
28	46
29	46
30	46
31	46

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	99	1
4	99	1
5	99	1
6	99	1
7	99	1
8	99	1
9	98	2
10	98	2
11	98	2
12	98	2
13	98	2
14	98	2
15	98	2
16	98	2
17	97	3
18	97	3
19	97	3
20	97	3
21	97	3
22	97	3
23	97	3
24	96	4
25	96	4
26	96	4
27	96	4
28	96	4
29	95	5
30	95	5
31	95	5

	Avg high (°C)	Avg low (°C)
1	13	6
2	13	6
3	13	6
4	13	6
5	13	6
6	13	6
7	13	6
8	14	6
9	14	6
10	14	7
11	14	7
12	14	7
13	14	7
14	14	7
15	14	7
16	14	7
17	14	7
18	15	7
19	15	7
20	15	8
21	15	8
22	15	8
23	15	8
24	15	8
25	15	8
26	15	8
27	16	8
28	16	8
29	16	9
30	16	9
31	16	9

	Clearer (%)	Cloudier (%)
1	30	70
2	30	70
3	30	70
4	29	71
5	29	71
6	29	71
7	29	71
8	29	71
9	29	71
10	28	72
11	27	73
12	27	73
13	26	74
14	26	74
15	26	74
16	26	74
17	25	75
18	25	75
19	26	74
20	25	75
21	25	75
22	25	75
23	25	75
24	26	74
25	26	74
26	26	74
27	27	73
28	27	73
29	27	73
30	27	73
31	29	71

	Rain chance (%)
1	47
2	47
3	47
4	47
5	47
6	47
7	47
8	47
9	47
10	47
11	47
12	47
13	48
14	48
15	48
16	47
17	47
18	47
19	46
20	46
21	46
22	46
23	46
24	46
25	46
26	46
27	46
28	46
29	46
30	46
31	46

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	99	1
4	99	1
5	99	1
6	99	1
7	99	1
8	99	1
9	98	2
10	98	2
11	98	2
12	98	2
13	98	2
14	98	2
15	98	2
16	98	2
17	97	3
18	97	3
19	97	3
20	97	3
21	97	3
22	97	3
23	97	3
24	96	4
25	96	4
26	96	4
27	96	4
28	96	4
29	95	5
30	95	5
31	95	5