Lowell weather in September

In September, Lowell sees average daytime highs of 73°F and overnight lows near 55°F, with 3.3 in of rain across 8.2 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 7th-wettest month of the year here.

Highs ease over the month, from about 78°F in the first days to 68°F by the end. The sky is clear or mostly clear about 38% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Lowell's 1st-clearest and 9th-windiest month. For the whole year in context, see Lowell's year-round climate.

Daytime high
73°
4th warmest
Overnight low
55°
9th coldest
Rainfall
3.3 in
8.2 wet days
Daylight
12 h 18 min
5:31 AM – 5:48 PM
Cloud cover
55%
1st clearest
Wind
6 mph
9th windiest
Solar energy
4.12 kWh/m²
Travel score
7.0
out of 10

Lowell is city in Middlesex County, Massachusetts, United States.

Density
2,942/km²
people per km²
Founded
1653

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 78°F in the first days to 68°F by the end.

A typical September day in Lowell reaches about 73°F in the afternoon and slips back to 55°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 64°F and 84°F. Set against its neighbours, September runs about 8°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17860
27859
37859
47759
57758
67758
77658
87658
97657
107557
117556
127456
137456
147455
157355
167355
177354
187254
197254
207253
217153
227153
237152
247052
257052
266951
276951
286851
296850
306750

How September really feels in Lowell

Once humidity and wind are folded in, September 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

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

Lowell weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan34° / 19°3.29.66.59.20.0
Feb37° / 20°3.08.7610.30.0
Mar45° / 28°4.110.9511.60.9
Apr57° / 39°3.710.61.413.13.9
May67° / 49°3.110.4014.46.0
Jun77° / 58°3.410.6015.16.5
Jul83° / 64°3.29.7014.86.0
Aug81° / 62°3.39.3013.76.6
Sep73° / 55°3.38.2012.37.0
Oct61° / 44°3.89.50.310.85.2
Nov49° / 34°3.49.31.39.62.1
Dec39° / 25°4.110.35.28.90.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 38% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 47%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15446
25446
35347
45347
55248
65347
75347
85347
95347
105347
115347
125446
135446
145446
155446
165446
175446
185446
195347
205347
215347
225248
235248
245347
255347
265248
275248
285248
295248
305248

Chance of precipitation in September

Any precipitation

Lowell gets around 3.3 in of rain over 8.2 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 27% and peaks near 29% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
125
225
326
426
527
627
728
828
928
1028
1128
1228
1328
1428
1527
1627
1727
1827
1927
2027
2127
2227
2327
2427
2527
2628
2728
2828
2929
3029

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 55% of days. Sticky, muggy-or-worse air turns up on roughly 10% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1372719143
2382719143
3392718133
4402618133
5412618122
6432617122
7442517122
8452517112
9462517112
10472417112
11482316111
12492316101
13512216101
1453211691
1553211691
1655201591
1756201581
1857191581
1958191481
2061181470
2162181370
2263171370
2365171260
2465171260
2568161150
2668161150
2770161040
2871151040
297215940
307514830

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 6 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over September. Sunrise moves from 5:14 AM to 5:47 AM, and sunset from 6:15 PM to 5:22 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:146:15
213.05:166:14
312.95:176:12
412.95:186:10
512.85:196:08
612.85:206:07
712.75:216:05
812.75:226:03
912.65:236:01
1012.65:245:59
1112.55:265:57
1212.55:275:56
1312.45:285:54
1412.45:295:52
1512.35:305:50
1612.35:315:48
1712.25:325:46
1812.25:335:44
1912.15:345:43
2012.15:365:41
2112.05:375:39
2212.05:385:37
2311.95:395:35
2411.95:405:33
2511.85:415:31
2611.85:425:30
2711.75:435:28
2811.75:455:26
2911.65:465:24
3011.65:475:22

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.12 kWh/m².

For context, solar energy here swings from a low near 1.58 kWh/m² to a high of 5.9 kWh/m² in July across the year — September's 4.12 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.7Bright
34.7Bright
44.7Bright
54.6Bright
64.5Bright
74.5Bright
84.5Bright
94.4Bright
104.4Bright
114.3Bright
124.3Bright
134.2Bright
144.2Bright
154.2Bright
164.1Bright
174.1Bright
184.0Bright
194.0Bright
204.0Moderate
213.9Moderate
223.9Moderate
233.8Moderate
243.8Moderate
253.7Moderate
263.7Moderate
273.6Moderate
283.6Moderate
293.5Moderate
303.5Moderate
Planning a trip in September

Hazard calendar for Lowell

In seasonPeak

In September, Lowell sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Lowell 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 September a good time to visit Lowell?

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

7.0
Sightseeing
1st-best month of the year
5.3
Beach & pool
4th-best month of the year

September is one of the better times to visit Lowell for general sightseeing.

What to pack for Lowell in September

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

In September, Lowell sees daytime highs around 73°F and nights near 55°F. Worth packing: light clothes and rain gear. About 8 days see rain.

light clothesrain gear

Sea temperature near Lowell in September

The nearest coast averages about 63°F in September — 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 Lowell in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September 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 Lowell 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 January 1 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 highHighHighModerateLowJul 10UV 7Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr5High
May7High
Jun7High
Jul7Very high
Aug5Moderate
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Lowell in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Lowell 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 Lowell?

Lowell sits at 42.6°N, 71.3°W, 118 ft above sea level, in United States. The nearest listed city is Dracut, 2.5 mi away.

Topography around Lowell

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

Within 2 miles, the terrain around Lowell has only modest variations in elevation — a maximum elevation change of 269 ft around an average of 131 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 594 ft; within 50 miles, large variations in elevation — a maximum elevation change of 3,176 ft.

The land around Lowell is covered by artificial surfaces (48%) and trees (40%) within 2 miles, trees (79%) within 10 miles, and trees (73%) within 50 miles.

2 miles
269 ft
10 miles
594 ft
50 miles
3,176 ft
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Dracut 2.5 mi · Chelmsford 3.7 mi · Tewksbury 4.3 mi · Billerica 5.6 mi · Westford 7.5 mi · Methuen 9.3 mi · Lawrence 9.3 mi · Wilmington 9.3 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 Lowell (42.6334°, -71.3162°, elevation 118 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).