Grantham weather in September

In September, Grantham sees average daytime highs of 18°C and overnight lows near 10°C, with 54 mm of rain across 9.4 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 19°C in the first days to 17°C by the end. The sky is clear or mostly clear about 11% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 30 min at the start of September to 11 h 24 min by month's end. Set against the rest of the year, September is Grantham's 6th-clearest and 9th-windiest month. For the whole year in context, see Grantham's year-round climate.

Daytime high
18°
4th warmest
Overnight low
10°
9th coldest
Rainfall
54 mm
9.4 wet days
Daylight
12 h 24 min
5:45 AM – 6:09 PM
Cloud cover
72%
6th clearest
Wind
15 km/h
9th windiest
Solar energy
2.87 kWh/m²
Travel score
5.7
out of 10

Grantham is market town and civil parish in South Kesteven, Lincolnshire, England.

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 19°C in the first days to 17°C by the end.

A typical September day in Grantham reaches about 18°C in the afternoon and slips back to 10°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 22°C. Set against its neighbours, September runs about 3°C cooler than August and about 4°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
12012
22011
31911
41911
51911
61911
71911
81911
91911
101911
111911
121911
131811
141811
151811
161810
171810
181810
191810
201810
211710
221710
231710
241710
251710
261710
271710
281710
29169
30169

How September really feels in Grantham

Once humidity and wind are folded in, September 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
0
heat index over the day's high
Days feeling ≤ C
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.

Grantham weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 4811.31.17.90.8
Feb / 389.51.49.51.2
Mar10° / 4410.20.911.52.2
Apr13° / 5111.10.213.63.4
May16° / 5310.8015.54.7
Jun19° / 11°6411.3016.65.6
Jul21° / 13°6310.9016.16.2
Aug21° / 13°6511014.56.1
Sep18° / 10°549.4012.45.7
Oct14° / 6010.9010.33.9
Nov10° / 56110.28.42.1
Dec / 5311.11.17.41.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 11% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 72%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13169
23169
33070
43070
53070
63169
73169
83169
93169
103169
113169
123070
133070
142971
152971
162872
172872
182773
192773
202674
212674
222575
232575
242575
252575
262674
272674
282575
292575
302575

Chance of precipitation in September

Any precipitation

Grantham gets around 54 mm of rain over 9.4 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 32% and peaks near 36% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
130
229
329
429
529
629
729
829
930
1030
1130
1231
1331
1431
1532
1632
1732
1832
1932
2033
2133
2233
2333
2434
2534
2635
2735
2835
2936
3036

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 83% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
175223
277212
377212
478202
578202
678202
779192
879192
979183
1080173
1181172
1282162
1383152
1483152
1584142
1684142
1784142
1886131
1986131
2086131
2185141
2286140
2387130
2487130
2587130
2688120
2788120
2889110
2989110
3090100

Wind in September

Winds average 15 km/h in September.

Across September, daily wind ranges from about 15 km/h on the calmest days to 16 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
515light breeze
615light breeze
715light breeze
815light breeze
915light breeze
1015light breeze
1115light breeze
1215light breeze
1315light breeze
1415light breeze
1515light breeze
1615light breeze
1715light breeze
1815light breeze
1915light breeze
2015light breeze
2116light breeze
2216light breeze
2316light breeze
2416light breeze
2516light breeze
2616light breeze
2716light breeze
2816light breeze
2916light breeze
3016light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 30 min at the start of September to 11 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 126 minutes over September. Sunrise moves from 5:18 AM to 6:09 AM, and sunset from 6:46 PM to 5:34 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.55:186:46
213.45:206:44
313.35:226:41
413.35:246:39
513.25:256:36
613.15:276:34
713.05:296:32
813.05:316:29
912.95:326:27
1012.85:346:24
1112.85:366:22
1212.75:386:19
1312.65:396:17
1412.65:416:14
1512.55:436:12
1612.45:456:09
1712.35:466:07
1812.35:486:04
1912.25:506:02
2012.15:525:59
2112.15:535:57
2212.05:555:54
2311.95:575:52
2411.85:595:49
2511.86:015:47
2611.76:025:44
2711.66:045:42
2811.66:065:39
2911.56:085:37
3011.46:095:34

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.87 kWh/m².

For context, solar energy here swings from a low near 0.58 kWh/m² to a high of 4.95 kWh/m² in June across the year — September's 2.87 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.5Moderate
23.4Moderate
33.4Moderate
43.4Moderate
53.3Moderate
63.3Moderate
73.2Moderate
83.2Moderate
93.1Moderate
103.1Moderate
113.1Moderate
123.0Moderate
133.0Moderate
142.9Moderate
152.9Moderate
162.8Moderate
172.8Moderate
182.7Moderate
192.7Moderate
202.6Moderate
212.6Moderate
222.6Moderate
232.5Moderate
242.5Moderate
252.4Moderate
262.4Moderate
272.4Moderate
282.3Moderate
292.3Moderate
302.2Moderate
Planning a trip in September

Is September a good time to visit Grantham?

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

5.7
Sightseeing
3rd-best month of the year
1.9
Beach & pool
4th-best month of the year

September is a reasonable time to visit Grantham for sightseeing.

What to pack for Grantham in September

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

In September, Grantham sees daytime highs around 18°C and nights near 10°C. Worth packing: rain gear. About 9 days see rain.

rain gear

Sea temperature near Grantham in September

The nearest coast averages about 16°C 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 68 km away) is warmest in August at about 18°C and coldest in February near 5°C.

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

5°10°15°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°C)Comfort
Jan6Bracing
Feb5Bracing
Mar6Bracing
Apr8Bracing
May11Bracing
Jun14Bracing
Jul17Cool
Aug18Cool
Sep16Cool
Oct13Bracing
Nov10Bracing
Dec7Bracing

UV index in Grantham in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Grantham peaks around August 11 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.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateLowAug 11UV 6Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr3Moderate
May5High
Jun6High
Jul6High
Aug6High
Sep4Moderate
Oct2Low
Nov1Low
Dec1Low
Location & terrain

Where is Grantham?

Grantham sits at 52.9°N, 0.6°W, 64 m above sea level, in United Kingdom. The nearest listed city is Sleaford, 18 km away.

Topography around Grantham

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

Within 3 km, the terrain around Grantham has only modest variations in elevation — a maximum elevation change of 90 m around an average of 84 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 170 m; within 80 km, significant variations in elevation — a maximum elevation change of 494 m.

The land around Grantham is covered by cropland (31%), artificial surfaces (26%) and trees (22%) within 3 km, cropland (66%) and grassland (21%) within 16 km, and cropland (53%) and grassland (25%) within 80 km.

3 km
90 m
16 km
170 m
80 km
494 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Sleaford 18 km · Newark on Trent 21 km · Melton Mowbray 23 km · Stamford 31 km · West Bridgford 32 km · Arnold 34 km · Nottingham 34 km · Spalding 36 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
Christian 60%none 26%Muslim 4%other 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 Grantham (52.9115°, -0.6418°, elevation 64 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).