Acton weather in May

In May, Acton sees average daytime highs of 67°F and overnight lows near 49°F, with 3.1 in of rain across 10.5 wet days and about 14.4 hours of daylight. It is the 5th-warmest and 11th-wettest month of the year here.

Highs climb over the month, from about 63°F in the first days to 72°F by the end. The sky is clear or mostly clear about 23% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of May to 14 h 54 min by month's end. Set against the rest of the year, May is Acton's 12th-clearest and 8th-windiest month. For the whole year in context, see Acton's year-round climate.

Daytime high
67°
5th warmest
Overnight low
49°
8th coldest
Rainfall
3.1 in
10.5 wet days
Daylight
14 h 24 min
4:30 AM – 6:54 PM
Cloud cover
66%
12th clearest
Wind
7 mph
8th windiest
Solar energy
5.47 kWh/m²
Travel score
6.0
out of 10

Acton is town in Massachusetts, United States.

Founded
1639

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

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 63°F in the first days to 72°F by the end.

A typical May day in Acton reaches about 67°F in the afternoon and slips back to 49°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 55°F and 81°F. Set against its neighbours, May runs about 10°F warmer than April and about 10°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16344
26345
36345
46446
56446
66446
76546
86547
96547
106547
116647
126647
136648
146748
156748
166749
176849
186849
196849
206950
216950
227051
237051
247051
257152
267152
277152
287253
297253
307253
317354

How May really feels in Acton

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
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.

Acton weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan35° / 20°3.29.66.29.20.0
Feb37° / 22°3.08.55.710.30.0
Mar45° / 29°4.111.15.111.61.1
Apr57° / 39°3.610.51.213.14.0
May67° / 49°3.110.5014.46.0
Jun77° / 58°3.510.7015.16.5
Jul83° / 64°3.210.3014.85.8
Aug81° / 62°3.49.6013.76.5
Sep73° / 55°3.48012.37.0
Oct61° / 44°3.79.30.210.85.3
Nov50° / 34°3.39.11.19.62.3
Dec40° / 26°4.110.358.90.1

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in May, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 62%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13862
23763
33763
43763
53862
63763
73763
83862
93862
103862
113862
123862
133862
143862
153862
163862
173862
183961
193961
203961
213862
223862
233862
243862
253961
263961
274060
283961
294060
303961
313961

Chance of precipitation in May

Any precipitation

Acton gets around 3.1 in of rain over 10.5 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 34% and peaks near 35% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
135
235
334
434
534
634
734
834
934
1034
1134
1235
1335
1435
1535
1635
1735
1835
1935
2035
2134
2234
2334
2433
2533
2633
2732
2832
2932
3032
3132

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 85% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
195410
295410
394510
494510
594510
693520
792620
892620
992620
1092620
1191720
1291720
1391720
1490730
1590730
1689830
1788840
1886941
1985951
20841051
21821161
22811171
23801271
24771382
25751492
26751492
277315102
287116103
297016113
306917113
316817123

Wind in May

Winds average 7 mph in May.

Across May, daily wind ranges from about 7 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 48 min at the start of May to 14 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over May. Sunrise moves from 4:48 AM to 4:18 AM, and sunset from 6:38 PM to 7:09 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.84:486:38
213.94:476:39
313.94:456:40
414.04:446:41
514.04:436:42
614.04:416:43
714.14:406:45
814.14:396:46
914.24:386:47
1014.24:366:48
1114.24:356:49
1214.34:346:50
1314.34:336:51
1414.34:326:52
1514.44:316:53
1614.44:306:54
1714.44:296:55
1814.54:286:56
1914.54:276:57
2014.54:266:58
2114.64:256:59
2214.64:247:00
2314.64:237:01
2414.74:227:02
2514.74:227:03
2614.74:217:04
2714.84:207:05
2814.84:197:06
2914.84:197:07
3014.84:187:08
3114.94:187:09

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.47 kWh/m².

For context, solar energy here swings from a low near 1.59 kWh/m² to a high of 5.88 kWh/m² in July across the year — May's 5.47 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.1Bright
25.2Bright
35.2Bright
45.2Bright
55.2Bright
65.2Bright
75.3Bright
85.3Bright
95.3Bright
105.3Bright
115.3Bright
125.4Bright
135.4Bright
145.4Bright
155.4Bright
165.5Bright
175.5Bright
185.5Bright
195.5Bright
205.6Bright
215.6Bright
225.6Bright
235.6Bright
245.7Bright
255.7Bright
265.7Bright
275.7Bright
285.7Bright
295.7Bright
305.7Bright
315.7Bright
Planning a trip in May

Hazard calendar for Acton

In seasonPeak

None of Acton's seasonal hazards are active in May. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Acton sits in the Atlantic hurricane belt; the season peaks August–October.

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

Is May a good time to visit Acton?

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

6.0
Sightseeing
4th-best month of the year
3.1
Beach & pool
5th-best month of the year

May is a reasonable time to visit Acton for sightseeing.

What to pack for Acton in May

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

In May, Acton sees daytime highs around 67°F and nights near 49°F. Worth packing: rain gear and sun protection. About 11 days see rain.

rain gearsun protection

Sea temperature near Acton in May

The nearest coast averages about 50°F 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 29 mi away) is warmest in August at about 66°F and coldest in February near 38°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

40°50°60°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°F)Comfort
Jan41Bracing
Feb38Bracing
Mar38Bracing
Apr42Bracing
May50Bracing
Jun58Bracing
Jul65Cool
Aug66Cool
Sep63Cool
Oct56Bracing
Nov50Bracing
Dec46Bracing

UV index in Acton in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Acton peaks around July 10 at about 7 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 23 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 10UV 7Dec 23UV 1
UV index (midday)Level
Jan1Low
Feb3Moderate
Mar4Moderate
Apr5High
May7Very high
Jun7Very high
Jul7Very high
Aug5Moderate
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Acton in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in Acton is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (November, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1715 µg/m³Nov 188 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb13Moderate
Mar13Moderate
Apr13Moderate
May14Moderate
Jun13Moderate
Jul16Moderate
Aug14Moderate
Sep11Good
Oct9Good
Nov8Good
Dec9Good
Location & terrain

Where is Acton?

Acton sits at 42.5°N, 71.4°W, 266 ft above sea level, in United States. The nearest listed city is Concord, 4.3 mi away.

Topography around Acton

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Acton.

Within 2 miles, the terrain around Acton has only modest variations in elevation — a maximum elevation change of 315 ft around an average of 236 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 574 ft; within 50 miles, large variations in elevation — a maximum elevation change of 3,176 ft.

The land around Acton is covered by trees (86%) within 2 miles, trees (84%) within 10 miles, and trees (77%) within 50 miles.

2 miles
315 ft
10 miles
574 ft
50 miles
3,176 ft
treesgrasslandcroplandartificial surfaceswaterwetland
May weather nearby: Concord 4.3 mi · Westford 6.2 mi · Sudbury 6.8 mi · Chelmsford 8.7 mi · Billerica 9.9 mi · Lexington 11 mi · Marlborough 11 mi · Lowell 12 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

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 Acton (42.4851°, -71.4328°, elevation 266 ft), 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).