Climate and average weather in Swellendam
In Swellendam, the summers are hot, fairly dry, and mostly clear and the winters are mild and mostly clear.
Over the course of the year, the temperature in Swellendam typically varies from 6°C to 28°C, and is rarely below 1°C or above 34°C. February is the hottest month of the year, while July is the coldest.
Based on the travel score, Swellendam has no single best season — it scores well the whole year round, so any month is a good time to visit for warm-weather activities.
- Hottest
- Feb
- 28°
- Coldest
- Jul
- 6°
- Wettest
- Nov
- 40 mm
- Driest
- Feb
- 23 mm
- Rain / yr
- 383 mm
- 69 wet days
- Daylight
- 9.7–14.3 h
- shortest–longest
- Elevation
- 128 m
- 34.0°S
- Clearest
- Feb
- 36% cloud
Swellendam is town in Western Cape, South Africa.
- Founded
- 1746
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Swellendam weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score holds near its peak the whole year round.
Temperature through the year
Daily average highs and lows in Swellendam, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.9 months, from November 27 to March 24, with daily high temperatures above 26°C. The hottest month of the year in Swellendam is February, with an average high of 28°C and low of 16°C.
The cool season lasts 3.2 months, from May 27 to September 1, with daily high temperatures below 20°C. The coldest month of the year in Swellendam is July, with an average low of 6°C and high of 18°C.
Days typically run about 12°C warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 28 | 27 | 24 | 21 | 18 | 18 | 19 | 21 | 23 | 25 | 27 |
| Avg low (°C) | 16 | 16 | 15 | 12 | 9 | 7 | 6 | 7 | 9 | 11 | 13 | 15 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 28 | 16 |
| Feb | 28 | 16 |
| Mar | 27 | 15 |
| Apr | 24 | 12 |
| May | 21 | 9 |
| Jun | 18 | 7 |
| Jul | 18 | 6 |
| Aug | 19 | 7 |
| Sep | 21 | 9 |
| Oct | 23 | 11 |
| Nov | 25 | 13 |
| Dec | 27 | 15 |
Average hourly temperature in Swellendam
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on February afternoons, near 28°C, and coldest before dawn in July, near 6°C.
Swellendam weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 28° / 16° | 28 | 5.1 | 14 | 7.0 |
| Feb | 28° / 16° | 23 | 5.3 | 13.3 | 7.0 |
| Mar | 27° / 15° | 35 | 6 | 12.3 | 7.5 |
| Apr | 24° / 12° | 37 | 6.1 | 11.2 | 7.7 |
| May | 21° / 9° | 30 | 5.4 | 10.3 | 7.5 |
| Jun | 18° / 7° | 31 | 6.1 | 9.8 | 6.9 |
| Jul | 18° / 6° | 33 | 6 | 10 | 6.8 |
| Aug | 19° / 7° | 33 | 6.5 | 10.7 | 6.9 |
| Sep | 21° / 9° | 24 | 5.7 | 11.8 | 7.3 |
| Oct | 23° / 11° | 39 | 5.5 | 12.9 | 7.8 |
| Nov | 25° / 13° | 40 | 5.8 | 13.8 | 7.7 |
| Dec | 27° / 15° | 29 | 5.4 | 14.2 | 7.4 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Swellendam gets about 383 mm of precipitation a year. On a typical day the chance of rain is some rain, and that barely changes with the seasons — rain is spread fairly evenly through the year.
November is the wettest month by volume, with 40 mm over about 6 wet days; February is the driest, with 23 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 17 | 19 | 19 | 20 | 18 | 20 | 19 | 20 | 19 | 18 | 19 | 18 |
| Rain days | 5 | 5 | 6 | 6 | 5 | 6 | 6 | 7 | 6 | 6 | 6 | 5 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 17 | 5 |
| Feb | 19 | 5 |
| Mar | 19 | 6 |
| Apr | 20 | 6 |
| May | 18 | 5 |
| Jun | 20 | 6 |
| Jul | 19 | 6 |
| Aug | 20 | 7 |
| Sep | 19 | 6 |
| Oct | 18 | 6 |
| Nov | 19 | 6 |
| Dec | 18 | 5 |
Monthly rainfall
Over a full year, Swellendam collects about 383 mm of rain across 69 wet days — roughly 32 mm in an average month.
It doesn’t fall evenly. November is the wettest month with 40 mm, while February is the driest at just 23 mm. The three wettest months alone bring about 30% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 28 | 23 | 35 | 37 | 30 | 31 | 33 | 33 | 24 | 39 | 40 | 29 |
| Rain days | 5 | 5 | 6 | 6 | 5 | 6 | 6 | 7 | 6 | 6 | 6 | 5 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 28 | 5 |
| Feb | 23 | 5 |
| Mar | 35 | 6 |
| Apr | 37 | 6 |
| May | 30 | 5 |
| Jun | 31 | 6 |
| Jul | 33 | 6 |
| Aug | 33 | 7 |
| Sep | 24 | 6 |
| Oct | 39 | 6 |
| Nov | 40 | 6 |
| Dec | 29 | 5 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Swellendam, the average share of the sky covered by clouds shows moderate seasonal variation over the course of the year.
The clearer part of the year begins around June 5 and lasts for 2.6 months, ending around August 22. The clearest month is January, when the sky is clear, mostly clear, or partly cloudy 74% of the time on average.
The cloudier part of the year begins around August 23 and lasts for 3.8 months, ending around December 17. The cloudiest month is October, when it is overcast or mostly cloudy 41% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 74 | 73 | 70 | 64 | 65 | 73 | 72 | 69 | 62 | 59 | 63 | 68 |
| Cloudier (%) | 26 | 27 | 30 | 36 | 35 | 27 | 28 | 31 | 38 | 41 | 37 | 32 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 74 | 26 |
| Feb | 73 | 27 |
| Mar | 70 | 30 |
| Apr | 64 | 36 |
| May | 65 | 35 |
| Jun | 73 | 27 |
| Jul | 72 | 28 |
| Aug | 69 | 31 |
| Sep | 62 | 38 |
| Oct | 59 | 41 |
| Nov | 63 | 37 |
| Dec | 68 | 32 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around December 15, brings about 14 h 18 min of light; the shortest, around June 16, only 9 h 42 min — a swing of roughly 4 h 36 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 14.0 | 13.3 | 12.3 | 11.2 | 10.3 | 9.8 | 10.0 | 10.7 | 11.8 | 12.9 | 13.8 | 14.2 |
| Sunrise (AM) | 5:46 | 6:15 | 6:40 | 7:04 | 7:27 | 7:46 | 7:46 | 7:21 | 6:39 | 5:57 | 5:29 | 5:27 |
| Sunset (PM) | 7:49 | 7:31 | 6:56 | 6:13 | 5:42 | 5:31 | 5:42 | 6:04 | 6:26 | 6:49 | 7:18 | 7:42 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 14.0 | 5:46 | 7:49 |
| Feb | 13.3 | 6:15 | 7:31 |
| Mar | 12.3 | 6:40 | 6:56 |
| Apr | 11.2 | 7:04 | 6:13 |
| May | 10.3 | 7:27 | 5:42 |
| Jun | 9.8 | 7:46 | 5:31 |
| Jul | 10.0 | 7:46 | 5:42 |
| Aug | 10.7 | 7:21 | 6:04 |
| Sep | 11.8 | 6:39 | 6:26 |
| Oct | 12.9 | 5:57 | 6:49 |
| Nov | 13.8 | 5:29 | 7:18 |
| Dec | 14.2 | 5:27 | 7:42 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Swellendam averages about 15 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 12 and 19 days.
The sunnier stretch runs 3.4 months, from around Dec 14 to Mar 26. The sunniest month is February, with roughly 18 sunny days (bright).
The greyest month is October, down near 13 sunny days — about 31% fewer than the February peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 19 | 17 | 17 | 14 | 14 | 16 | 17 | 15 | 13 | 13 | 13 | 16 |
| Sky | Bright | Bright | Bright | Mixed | Mixed | Bright | Bright | Mixed | Mixed | Mixed | Mixed | Bright |
| Sunny days | Sky | |
|---|---|---|
| Jan | 19 | Bright |
| Feb | 17 | Bright |
| Mar | 17 | Bright |
| Apr | 14 | Mixed |
| May | 14 | Mixed |
| Jun | 16 | Bright |
| Jul | 17 | Bright |
| Aug | 15 | Mixed |
| Sep | 13 | Mixed |
| Oct | 13 | Mixed |
| Nov | 13 | Mixed |
| Dec | 16 | Bright |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Swellendam, how humid it feels changes noticeably over the year.
The more humid part of the year lasts 3.8 months, from around December 8 to April 1. The muggiest month is February, when the air feels humid, muggy or worse about 26% of the time.
The most comfortable stretch runs from around April 2 to December 7, and May is the most comfortable month — the air is dry or comfortable 100% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 39 | 29 | 43 | 75 | 96 | 100 | 100 | 99 | 98 | 90 | 82 | 59 |
| Comfortable (%) | 41 | 45 | 42 | 23 | 4 | 0 | 0 | 1 | 2 | 10 | 16 | 31 |
| Humid (%) | 18 | 24 | 15 | 3 | 0 | 0 | 0 | 0 | 0 | 1 | 3 | 11 |
| Muggy (%) | 2 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| Jan | 39 | 41 | 18 | 2 |
| Feb | 29 | 45 | 24 | 2 |
| Mar | 43 | 42 | 15 | 0 |
| Apr | 75 | 23 | 3 | 0 |
| May | 96 | 4 | 0 | 0 |
| Jun | 100 | 0 | 0 | 0 |
| Jul | 100 | 0 | 0 | 0 |
| Aug | 99 | 1 | 0 | 0 |
| Sep | 98 | 2 | 0 | 0 |
| Oct | 90 | 10 | 1 | 0 |
| Nov | 82 | 16 | 3 | 0 |
| Dec | 59 | 31 | 11 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Swellendam is typically calm, near 10 km/h, and varies little with the seasons.
The windier part of the year lasts 5.6 months, from around Sep 20 to Mar 8. The windiest month is December, averaging about 11 km/h (calm).
The calmer part of the year runs from around Mar 9 to Sep 19, with May the calmest month at about 8 km/h.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 11 | 10 | 9 | 8 | 8 | 9 | 9 | 9 | 9 | 10 | 11 | 11 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 11 | calm |
| Feb | 10 | calm |
| Mar | 9 | calm |
| Apr | 8 | calm |
| May | 8 | calm |
| Jun | 9 | calm |
| Jul | 9 | calm |
| Aug | 9 | calm |
| Sep | 9 | calm |
| Oct | 10 | calm |
| Nov | 11 | calm |
| Dec | 11 | calm |
Best time to visit Swellendam
To characterize how pleasant the weather is in Swellendam throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, Swellendam suits general outdoor tourist activities for most of the year, with a peak score in the second week of April.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 7.0 | 7.0 | 7.5 | 7.7 | 7.5 | 6.9 | 6.8 | 6.9 | 7.3 | 7.7 | 7.7 | 7.4 |
| Rating | good | good | ideal | ideal | good | good | good | good | good | ideal | ideal | good |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 7.0 | good |
| Feb | 7.0 | good |
| Mar | 7.5 | ideal |
| Apr | 7.7 | ideal |
| May | 7.5 | good |
| Jun | 6.9 | good |
| Jul | 6.8 | good |
| Aug | 6.9 | good |
| Sep | 7.3 | good |
| Oct | 7.7 | ideal |
| Nov | 7.7 | ideal |
| Dec | 7.4 | good |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Swellendam for hot-weather activities is from late October to mid April, with a peak score in the third week of January.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Swellendam, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around February (highs near 28°C), the essentials are light clothes and sun protection. In the cold season around July (highs near 18°C), pack a warm layer.
In February, Swellendam sees daytime highs around 28°C and nights near 16°C. Pack light clothes and sun protection. About 5 days see rain.
Sea temperature near Swellendam
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 21 | 22 | 21 | 19 | 17 | 16 | 15 | 15 | 16 | 17 | 19 | 20 |
| Comfort | Refreshing | Refreshing | Refreshing | Cool | Cool | Cool | Cool | Cool | Cool | Cool | Cool | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 21 | Refreshing |
| Feb | 22 | Refreshing |
| Mar | 21 | Refreshing |
| Apr | 19 | Cool |
| May | 17 | Cool |
| Jun | 16 | Cool |
| Jul | 15 | Cool |
| Aug | 15 | Cool |
| Sep | 16 | Cool |
| Oct | 17 | Cool |
| Nov | 19 | Cool |
| Dec | 20 | Refreshing |
UV index (midday) in Swellendam by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 14 | 10 | 10 | 6 | 4 | 3 | 3 | 4 | 6 | 10 | 12 | 12 |
| Level | Extreme | Very high | Very high | High | Moderate | Moderate | Moderate | Moderate | High | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 14 | Extreme |
| Feb | 10 | Very high |
| Mar | 10 | Very high |
| Apr | 6 | High |
| May | 4 | Moderate |
| Jun | 3 | Moderate |
| Jul | 3 | Moderate |
| Aug | 4 | Moderate |
| Sep | 6 | High |
| Oct | 10 | Extreme |
| Nov | 12 | Extreme |
| Dec | 12 | Extreme |
Average hourly UV index in Swellendam
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in January the burn window is concentrated in the middle of the day: about 9 hours a day reach index 3 (protection recommended), and 7 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 9 | 8 | 7.5 | 5.5 | 3 | 0 | 1 | 4 | 5.5 | 8 | 8.5 | 9 |
| UV ≥ 6 (h/day) | 7 | 5.5 | 5 | 1 | 0 | 0 | 0 | 0 | 0 | 5.5 | 6.5 | 6.5 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 9 | 7 |
| Feb | 8 | 5.5 |
| Mar | 7.5 | 5 |
| Apr | 5.5 | 1 |
| May | 3 | 0 |
| Jun | 0 | 0 |
| Jul | 1 | 0 |
| Aug | 4 | 0 |
| Sep | 5.5 | 0 |
| Oct | 8 | 5.5 |
| Nov | 8.5 | 6.5 |
| Dec | 9 | 6.5 |
Air quality in Swellendam by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly 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).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 6 | 8 | 9 | 10 | 16 | 17 | 17 | 16 | 13 | 9 | 7 | 8 |
| Level | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 6 | Good |
| Feb | 8 | Good |
| Mar | 9 | Good |
| Apr | 10 | Good |
| May | 16 | Moderate |
| Jun | 17 | Moderate |
| Jul | 17 | Moderate |
| Aug | 16 | Moderate |
| Sep | 13 | Moderate |
| Oct | 9 | Good |
| Nov | 7 | Good |
| Dec | 8 | Good |
Growing season
Swellendam is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 99 | 97 | 99 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 99 | 0 |
| Jul | 97 | 0 |
| Aug | 99 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Swellendam banks about 2,662 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around February.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 377 | 344 | 335 | 238 | 164 | 73 | 55 | 84 | 149 | 226 | 271 | 345 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 377 |
| Feb | 344 |
| Mar | 335 |
| Apr | 238 |
| May | 164 |
| Jun | 73 |
| Jul | 55 |
| Aug | 84 |
| Sep | 149 |
| Oct | 226 |
| Nov | 271 |
| Dec | 345 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Swellendam receives about 5.1 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 2.6 and 7.6 kWh/m².
The brighter stretch of the year lasts 5.9 months, from around Sep 21 to Mar 20. The brightest month is December, averaging about 7.5 kWh/m² (intense).
The dimmest month is June, down near 2.7 kWh/m² — roughly 65% less than the December peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 7.4 | 6.5 | 5.3 | 4.0 | 3.1 | 2.6 | 2.9 | 3.6 | 4.9 | 6.0 | 7.1 | 7.5 |
| Level | Intense | Intense | Bright | Bright | Moderate | Moderate | Moderate | Moderate | Bright | Intense | Intense | Intense |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 7.4 | Intense |
| Feb | 6.5 | Intense |
| Mar | 5.3 | Bright |
| Apr | 4.0 | Bright |
| May | 3.1 | Moderate |
| Jun | 2.6 | Moderate |
| Jul | 2.9 | Moderate |
| Aug | 3.6 | Moderate |
| Sep | 4.9 | Bright |
| Oct | 6.0 | Intense |
| Nov | 7.1 | Intense |
| Dec | 7.5 | Intense |
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.
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
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).