Grimstad weather in September

In September, Grimstad sees average daytime highs of 16°C and overnight lows near 11°C, with 105 mm of rain across 12.4 wet days and about 12.5 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 18°C in the first days to 14°C by the end. The sky is clear or mostly clear about 26% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of September to 11 h 18 min by month's end. Set against the rest of the year, September is Grimstad's 6th-clearest and 7th-windiest month. For the whole year in context, see Grimstad's year-round climate.

Daytime high
16°
4th warmest
Overnight low
11°
9th coldest
Rainfall
105 mm
12.4 wet days
Daylight
12 h 30 min
6:05 AM – 6:35 PM
Cloud cover
64%
6th clearest
Wind
18 km/h
7th windiest
Solar energy
2.7 kWh/m²
Travel score
4.6
out of 10

Grimstad is settlement in Grimstad Municipality, Norway.

Density
2,552/km²
people per km²
Founded
1816

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 18°C in the first days to 14°C by the end.

A typical September day in Grimstad reaches about 16°C in the afternoon and slips back to 11°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 19°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11812
21812
31812
41712
51712
61712
71712
81712
91711
101711
111611
121611
131611
141611
151611
161611
171611
181610
191510
201510
211510
221510
231510
241510
251410
26149
27149
28149
29149
30149

How September really feels in Grimstad

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.

Grimstad weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -0°10714.47.66.80.0
Feb / -1°7911.478.90.0
Mar / 7110.14.811.40.4
Apr10° / 589.91.3142.1
May14° / 6310016.44.2
Jun18° / 11°759.5017.85.8
Jul20° / 14°729.7017.26.4
Aug20° / 14°10112015.16.0
Sep16° / 11°10512.4012.54.6
Oct11° / 11914.10.39.92.5
Nov / 11514.82.47.50.8
Dec / 104144.26.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% 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 57%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14456
24456
34357
44456
54456
64456
74357
84456
94456
104456
114555
124555
134555
144555
154456
164456
174456
184456
194357
204357
214357
224258
234159
244159
253961
263961
273961
283862
293862
303961

Chance of precipitation in September

Any precipitation

Grimstad gets around 105 mm of rain over 12.4 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 42% and peaks near 44% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
141
242
342
442
543
643
743
844
944
1044
1144
1244
1344
1443
1543
1642
1742
1841
1940
2040
2139
2239
2339
2439
2539
2640
2740
2841
2941
3041

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 86% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
177203
278193
378193
480182
580182
680182
781172
881172
981172
1082162
1182162
1284151
1384151
1485141
1586131
1686131
1787121
1889110
1989110
2090100
2190100
229190
239190
249280
259280
269370
279370
289460
299460
309550

Wind in September

Winds average 18 km/h in September.

Across September, daily wind ranges from about 16 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202530
Wind speed (km/h)Feels
116light breeze
216light breeze
316light breeze
417light breeze
517light breeze
617light breeze
717light breeze
817light breeze
917light breeze
1018light breeze
1118light breeze
1218light breeze
1318light breeze
1418light breeze
1518light breeze
1618light breeze
1718light breeze
1818light breeze
1918light breeze
2018light breeze
2118light breeze
2218light breeze
2318light breeze
2418light breeze
2518light breeze
2618light breeze
2718light breeze
2818light breeze
2918light breeze
3018light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 48 min at the start of September to 11 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 150 minutes over September. Sunrise moves from 5:31 AM to 6:37 AM, and sunset from 7:19 PM to 5:53 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.85:317:19
213.75:347:16
313.65:367:14
413.55:387:11
513.55:407:08
613.45:437:05
713.35:457:02
813.25:476:59
913.15:496:56
1013.05:516:53
1112.95:546:50
1212.85:566:47
1312.85:586:44
1412.76:006:41
1512.66:036:38
1612.56:056:35
1712.46:076:32
1812.36:096:29
1912.26:126:26
2012.26:146:23
2112.16:166:20
2212.06:186:17
2311.96:216:14
2411.86:236:11
2511.76:256:08
2611.66:276:05
2711.56:306:02
2811.56:325:59
2911.46:345:56
3011.36:375:53

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.7 kWh/m².

For context, solar energy here swings from a low near 0.28 kWh/m² to a high of 6.12 kWh/m² in June across the year — September's 2.7 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.5Moderate
23.5Moderate
33.4Moderate
43.3Moderate
53.3Moderate
63.2Moderate
73.1Moderate
83.1Moderate
93.0Moderate
103.0Moderate
112.9Moderate
122.9Moderate
132.8Moderate
142.8Moderate
152.7Moderate
162.7Moderate
172.6Moderate
182.6Moderate
192.5Moderate
202.5Moderate
212.4Moderate
222.4Moderate
232.3Moderate
242.3Moderate
252.2Moderate
262.2Moderate
272.1Moderate
282.1Moderate
292.0Moderate
302.0Dim
Planning a trip in September

Is September a good time to visit Grimstad?

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

4.6
Sightseeing
4th-best month of the year
0.6
Beach & pool
4th-best month of the year

September is a reasonable time to visit Grimstad for sightseeing.

What to pack for Grimstad in September

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

In September, Grimstad sees daytime highs around 16°C and nights near 11°C. Worth packing: a warm layer and rain gear. About 12 days see rain.

a warm layerrain gear

Sea temperature near Grimstad in September

The nearest coast averages about 15°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 18°C and coldest in February near 4°C.

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

0°5°10°15°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°C)Comfort
Jan5Bracing
Feb4Bracing
Mar4Bracing
Apr6Bracing
May10Bracing
Jun15Bracing
Jul17Cool
Aug18Cool
Sep15Cool
Oct12Bracing
Nov9Bracing
Dec7Bracing

UV index in Grimstad in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 3. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Grimstad peaks around August 10 at about 5 (moderate) — a little sun protection helps at midday. It bottoms out near December 20 at about 0 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 4 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateLowAug 10UV 5Dec 20UV 0
UV index (midday)Level
Jan0Low
Feb1Low
Mar2Low
Apr3Moderate
May5Moderate
Jun4Moderate
Jul5Moderate
Aug5Moderate
Sep3Moderate
Oct1Low
Nov1Low
Dec0Low
Location & terrain

Where is Grimstad?

Grimstad sits at 58.3°N, 8.6°E, 9 m above sea level, in Norway. The nearest listed city is Arendal, 17 km away.

Topography around Grimstad

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

Within 3 km, the terrain around Grimstad has only modest variations in elevation — a maximum elevation change of 124 m around an average of 29 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 340 m; within 80 km, large variations in elevation — a maximum elevation change of 930 m.

The land around Grimstad is covered by trees (39%) and water (30%) within 3 km, water (51%) and trees (40%) within 16 km, and trees (56%) and water (37%) within 80 km.

3 km
124 m
16 km
340 m
80 km
930 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Arendal 17 km · Kristiansand 41 km · Porsgrunn 108 km · Skien 113 km · Larvik 115 km · Hjørring 127 km · Sandefjord 128 km · Skagen 136 km

Norway travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 91% of US
price level, 2025
GDP per capita
$94,594
2025
Happiness
7.2 / 10
World Happiness, 2025
Safe drinking water
99%
of population, 2024
Homicide rate
0.7
per 100k, 2023
Road deaths
2.1
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 613
Religion
Church of Norway 68%other Christian 4%Muslim 3%Roman Catholic 3%

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 Grimstad (58.3405°, 8.5934°, elevation 9 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).