Swellendam weather in September

In September, Swellendam sees average daytime highs of 21°C and overnight lows near 9°C, with 24 mm of rain across 5.7 wet days and about 11.8 hours of daylight. It is the 9th-warmest and 11th-wettest month of the year here.

Highs climb over the month, from about 20°C in the first days to 22°C by the end. The sky is clear or mostly clear about 44% of the time in September, and the air most often feels dry.

Daylight stretches from about 11 h 18 min at the start of September to 12 h 18 min by month's end. Set against the rest of the year, September is Swellendam's 11th-clearest and 6th-windiest month. For the whole year in context, see Swellendam's year-round climate.

Daytime high
21°
9th warmest
Overnight low
4th coldest
Rainfall
24 mm
5.7 wet days
Daylight
11 h 48 min
6:39 AM – 6:26 PM
Cloud cover
46%
11th clearest
Wind
9 km/h
6th windiest
Solar energy
4.86 kWh/m²
Travel score
7.3
out of 10

Swellendam is town in Western Cape, South Africa.

Founded
1746

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 20°C in the first days to 22°C by the end.

A typical September day in Swellendam reaches about 21°C in the afternoon and slips back to 9°C overnight — a 12°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 27°C. Set against its neighbours, September runs about 2°C warmer than August and about 2°C cooler than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
1208
2208
3208
4208
5208
6208
7209
8219
9219
10219
11219
12219
13219
14219
15219
16219
17219
18219
19219
20219
21219
22229
23229
24229
25229
26229
272210
282210
292210
302210

Swellendam weather by month

How September compares with the rest of the year at a glance. September is the 9th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 16°285.1147.0
Feb28° / 16°235.313.37.0
Mar27° / 15°35612.37.5
Apr24° / 12°376.111.27.7
May21° / 305.410.37.5
Jun18° / 316.19.86.9
Jul18° / 336106.8
Aug19° / 336.510.76.9
Sep21° / 245.711.87.3
Oct23° / 11°395.512.97.8
Nov25° / 13°405.813.87.7
Dec27° / 15°295.414.27.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 44% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 38%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16634
26535
36535
46535
56436
66436
76436
86436
96337
106337
116337
126337
136337
146238
156238
166139
176139
186139
196139
206139
216139
226139
236139
246139
256040
266040
276040
286040
296040
305941

Chance of precipitation in September

Any precipitation

Swellendam gets around 24 mm of rain over 5.7 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 19% and peaks near 20% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
120
220
320
420
520
619
719
819
919
1018
1118
1218
1319
1419
1519
1619
1719
1820
1920
2020
2120
2220
2320
2420
2519
2619
2719
2818
2918
3018

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 98% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)
1991
2991
3991
4991
5991
6991
7982
8982
9982
10982
11982
12982
13982
14982
15973
16973
17973
18973
19973
20973
21973
22982
23982
24982
25982
26982
27982
28982
29982
30982

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 9 km/h on the calmest days to 10 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 18 min at the start of September to 12 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over September. Sunrise moves from 7:00 AM to 6:19 AM, and sunset from 6:16 PM to 6:37 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.37:006:16
211.36:596:16
311.36:576:17
411.46:566:18
511.46:556:18
611.46:536:19
711.56:526:20
811.56:506:21
911.56:496:21
1011.66:486:22
1111.66:466:23
1211.66:456:23
1311.76:436:24
1411.76:426:25
1511.86:406:26
1611.86:396:26
1711.86:376:27
1811.96:366:28
1911.96:346:28
2011.96:336:29
2112.06:326:30
2212.06:306:31
2312.06:296:31
2412.16:276:32
2512.16:266:33
2612.26:246:34
2712.26:236:34
2812.26:216:35
2912.36:206:36
3012.36:196:37

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.86 kWh/m².

For context, solar energy here swings from a low near 2.64 kWh/m² to a high of 7.53 kWh/m² in December across the year — September's 4.86 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
14.2Bright
24.3Bright
34.3Bright
44.4Bright
54.4Bright
64.4Bright
74.5Bright
84.5Bright
94.6Bright
104.6Bright
114.7Bright
124.7Bright
134.7Bright
144.8Bright
154.8Bright
164.9Bright
174.9Bright
185.0Bright
195.0Bright
205.0Bright
215.1Bright
225.1Bright
235.2Bright
245.2Bright
255.2Bright
265.3Bright
275.3Bright
285.4Bright
295.4Bright
305.4Bright
Planning a trip in September

Is September a good time to visit Swellendam?

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

7.3
Sightseeing
7th-best month of the year
4.5
Beach & pool
9th-best month of the year

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

What to pack for Swellendam in September

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

In September, Swellendam sees daytime highs around 21°C and nights near 9°C. Worth packing: sun protection. About 6 days see rain.

sun protection

Sea temperature near Swellendam 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 56 km away) is warmest in February at about 22°C and coldest in July near 15°C.

It's comfortable for a long swim from Dec 15 to Mar 26 — about 3.4 months when the water holds above 20°C.

15°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingcomfortable to swim
Sea temperature (°C)Comfort
Jan21Refreshing
Feb22Refreshing
Mar21Refreshing
Apr19Cool
May17Cool
Jun16Cool
Jul15Cool
Aug15Cool
Sep16Cool
Oct17Cool
Nov19Cool
Dec20Refreshing

UV index in Swellendam 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 Swellendam peaks around January 13 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highModerateExtremeJan 13UV 13Jun 20UV 3
UV index (midday)Level
Jan14Extreme
Feb10Very high
Mar10Very high
Apr6High
May4Moderate
Jun3Moderate
Jul3Moderate
Aug4Moderate
Sep6High
Oct10Extreme
Nov12Extreme
Dec12Extreme

Air quality in Swellendam 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 Swellendam is worst in June — around 17 µg/m³ PM2.5 (moderate), about 2.9× the cleanest month (January, 6 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJun 2017 µg/m³Jan 166 µg/m³
PM2.5 (µg/m³)Level
Jan6Good
Feb8Good
Mar9Good
Apr10Good
May16Moderate
Jun17Moderate
Jul17Moderate
Aug16Moderate
Sep13Moderate
Oct9Good
Nov7Good
Dec8Good
Location & terrain

Where is Swellendam?

Swellendam sits at 34.0°S, 20.4°E, 128 m above sea level, in South Africa. The nearest listed city is Montagu, 40 km away.

Topography around Swellendam

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

Within 3 km, the terrain around Swellendam has only modest variations in elevation — a maximum elevation change of 248 m around an average of 163 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,677 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,683 m.

The land around Swellendam is covered by trees (28%), grassland (25%) and shrubs (24%) within 3 km, grassland (33%), cropland (31%) and shrubs (24%) within 16 km, and grassland (38%), shrubs (27%) and cropland (22%) within 80 km.

3 km
248 m
16 km
1,677 m
80 km
1,683 m
treesshrubsgrasslandcroplandartificial surfaceswater
September weather nearby: Montagu 40 km · Ashton 41 km · Robertson 57 km · Bredasdorp 68 km · Riversdale 76 km · Caledon 96 km · Worcester 101 km · Gansbaai 118 km

South Africa travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / M / N
230 V · 50 Hz
Prices
≈ 41% of US
price level, 2025
GDP per capita
$6,598
2025
Happiness
5.0 / 10
World Happiness, 2025
Safe drinking water
68%
of population, 2024
Homicide rate
43.7
per 100k, 2022
Road deaths
22.2
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Very high
EF EPI 602
Religion
Christian 86%or other traditional African religions 5%nothing in particular 5%Muslim 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 Swellendam (-34.0226°, 20.4417°, elevation 128 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. 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).