Climate and average weather in Jamestown
In Jamestown, the weather is humid, warm, dry, and mostly clear and remarkably steady, with daytime highs holding near warm levels all year. The wettest stretch peaks around March.
Over the course of the year, the temperature in Jamestown typically varies from 19°C to 24°C, and is rarely below 18°C or above 25°C. March is the hottest month of the year, while September is the coldest.
Based on the travel score, the best time of year to visit Jamestown for warm-weather activities is from early January to late December.
- Hottest
- Mar
- 24°
- Coldest
- Sep
- 19°
- Wettest
- Mar
- 5 mm
- Driest
- Oct
- 1 mm
- Rain / yr
- 28 mm
- 6 wet days
- Daylight
- 11.1–12.9 h
- shortest–longest
- Elevation
- 10 m
- 15.9°S
- Clearest
- Feb
- 40% cloud
Jamestown is capital of Saint Helena.
- Density
- 177/km²
- people per km²
- Founded
- 1659
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Jamestown 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 climbs highest around early January to late December.
Temperature through the year
Daily average highs and lows in Jamestown, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
Temperatures in Jamestown stay fairly even through the year, without a distinct hot or cool season. The warmest month is March, with an average high of 24°C and low of 24°C; the coolest is September, with an average low of 19°C and high of 20°C.
Days typically run about 1°C warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 23 | 24 | 24 | 24 | 23 | 22 | 21 | 20 | 20 | 20 | 20 | 21 |
| Avg low (°C) | 22 | 23 | 24 | 23 | 22 | 21 | 20 | 19 | 19 | 19 | 20 | 21 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 23 | 22 |
| Feb | 24 | 23 |
| Mar | 24 | 24 |
| Apr | 24 | 23 |
| May | 23 | 22 |
| Jun | 22 | 21 |
| Jul | 21 | 20 |
| Aug | 20 | 19 |
| Sep | 20 | 19 |
| Oct | 20 | 19 |
| Nov | 20 | 20 |
| Dec | 21 | 21 |
Average hourly temperature in Jamestown
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 March afternoons, near 24°C, and coldest before dawn in September, near 19°C.
Jamestown 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 | 23° / 22° | 2 | 0.4 | 12.8 | 8.6 |
| Feb | 24° / 23° | 3 | 0.6 | 12.5 | 8.8 |
| Mar | 24° / 24° | 5 | 1.4 | 12.1 | 8.7 |
| Apr | 24° / 23° | 3 | 0.6 | 11.7 | 8.7 |
| May | 23° / 22° | 4 | 1.1 | 11.3 | 8.3 |
| Jun | 22° / 21° | 5 | 1.1 | 11.1 | 7.9 |
| Jul | 21° / 20° | 3 | 0.5 | 11.1 | 7.7 |
| Aug | 20° / 19° | 2 | 0.3 | 11.5 | 7.4 |
| Sep | 20° / 19° | 1 | 0.1 | 11.9 | 7.3 |
| Oct | 20° / 19° | 1 | 0.1 | 12.4 | 7.4 |
| Nov | 20° / 20° | 1 | 0 | 12.7 | 7.7 |
| Dec | 21° / 21° | 1 | 0 | 12.9 | 8.2 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Jamestown gets about 28 mm of precipitation a year. On a typical day the chance of rain is mostly dry, and that barely changes with the seasons — rain is spread fairly evenly through the year.
March is the wettest month by volume, with 5 mm over about 1 wet days; October is the driest, with 1 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 1 | 2 | 4 | 2 | 3 | 4 | 1 | 1 | 0 | 0 | 0 | 0 |
| Rain days | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 1 | 0 |
| Feb | 2 | 1 |
| Mar | 4 | 1 |
| Apr | 2 | 1 |
| May | 3 | 1 |
| Jun | 4 | 1 |
| Jul | 1 | 1 |
| Aug | 1 | 0 |
| Sep | 0 | 0 |
| Oct | 0 | 0 |
| Nov | 0 | 0 |
| Dec | 0 | 0 |
Monthly rainfall
Over a full year, Jamestown collects about 28 mm of rain across 6 wet days — roughly 2 mm in an average month.
It doesn’t fall evenly. March is the wettest month with 5 mm, while October is the driest at just 1 mm. The three wettest months alone bring about 46% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 2 | 3 | 5 | 3 | 4 | 5 | 3 | 2 | 1 | 1 | 1 | 1 |
| Rain days | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 2 | 0 |
| Feb | 3 | 1 |
| Mar | 5 | 1 |
| Apr | 3 | 1 |
| May | 4 | 1 |
| Jun | 5 | 1 |
| Jul | 3 | 1 |
| Aug | 2 | 0 |
| Sep | 1 | 0 |
| Oct | 1 | 0 |
| Nov | 1 | 0 |
| Dec | 1 | 0 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Jamestown, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around November 23 and lasts for 6.2 months, ending around May 31. The clearest month is February, when the sky is clear, mostly clear, or partly cloudy 87% of the time on average.
The cloudier part of the year begins around June 1 and lasts for 5.7 months, ending around November 22. The cloudiest month is September, when it is overcast or mostly cloudy 72% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 86 | 87 | 86 | 74 | 64 | 53 | 44 | 32 | 28 | 31 | 54 | 76 |
| Cloudier (%) | 14 | 13 | 14 | 26 | 36 | 47 | 56 | 68 | 72 | 69 | 46 | 24 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 86 | 14 |
| Feb | 87 | 13 |
| Mar | 86 | 14 |
| Apr | 74 | 26 |
| May | 64 | 36 |
| Jun | 53 | 47 |
| Jul | 44 | 56 |
| Aug | 32 | 68 |
| Sep | 28 | 72 |
| Oct | 31 | 69 |
| Nov | 54 | 46 |
| Dec | 76 | 24 |
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 January 1, brings about 12 h 54 min of light; the shortest, around May 29, only 11 h 06 min — a swing of roughly 1 h 48 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 12.8 | 12.5 | 12.1 | 11.7 | 11.3 | 11.1 | 11.1 | 11.5 | 11.9 | 12.4 | 12.7 | 12.9 |
| Sunrise (AM) | 6:07 | 6:22 | 6:29 | 6:34 | 6:41 | 6:51 | 6:54 | 6:43 | 6:20 | 5:57 | 5:45 | 5:51 |
| Sunset (PM) | 6:58 | 6:53 | 6:36 | 6:12 | 5:57 | 5:55 | 6:03 | 6:11 | 6:15 | 6:19 | 6:31 | 6:47 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 12.8 | 6:07 | 6:58 |
| Feb | 12.5 | 6:22 | 6:53 |
| Mar | 12.1 | 6:29 | 6:36 |
| Apr | 11.7 | 6:34 | 6:12 |
| May | 11.3 | 6:41 | 5:57 |
| Jun | 11.1 | 6:51 | 5:55 |
| Jul | 11.1 | 6:54 | 6:03 |
| Aug | 11.5 | 6:43 | 6:11 |
| Sep | 11.9 | 6:20 | 6:15 |
| Oct | 12.4 | 5:57 | 6:19 |
| Nov | 12.7 | 5:45 | 6:31 |
| Dec | 12.9 | 5:51 | 6:47 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Jamestown averages about 8 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 2 and 18 days.
The sunnier stretch runs 5.5 months, from around Dec 5 to May 20. The sunniest month is February, with roughly 17 sunny days (bright).
The greyest month is October, down near 2 sunny days — about 87% fewer than the February peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 16 | 16 | 16 | 11 | 9 | 6 | 5 | 3 | 2 | 2 | 5 | 11 |
| Sky | Bright | Bright | Bright | Mixed | Mixed | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 16 | Bright |
| Feb | 16 | Bright |
| Mar | 16 | Bright |
| Apr | 11 | Mixed |
| May | 9 | Mixed |
| Jun | 6 | Gloomy |
| Jul | 5 | Gloomy |
| Aug | 3 | Gloomy |
| Sep | 2 | Gloomy |
| Oct | 2 | Gloomy |
| Nov | 5 | Gloomy |
| Dec | 11 | Mixed |
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 Jamestown, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 6.5 months, from around November 22 to June 7. The muggiest month is January, when the air feels humid, muggy or worse about 99% of the time.
The most comfortable stretch runs from around June 8 to November 21, and August is the most comfortable month — the air is dry or comfortable 88% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 0 | 0 | 0 | 0 | 0 | 1 | 3 | 5 | 3 | 1 | 0 | 0 |
| Comfortable (%) | 1 | 0 | 0 | 1 | 10 | 46 | 76 | 83 | 77 | 60 | 40 | 13 |
| Humid (%) | 47 | 20 | 15 | 38 | 71 | 52 | 21 | 12 | 20 | 39 | 59 | 74 |
| Muggy (%) | 52 | 74 | 73 | 57 | 18 | 1 | 0 | 0 | 0 | 0 | 1 | 13 |
| Oppressive (%) | 1 | 6 | 11 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | |
|---|---|---|---|---|---|
| Jan | 0 | 1 | 47 | 52 | 1 |
| Feb | 0 | 0 | 20 | 74 | 6 |
| Mar | 0 | 0 | 15 | 73 | 11 |
| Apr | 0 | 1 | 38 | 57 | 4 |
| May | 0 | 10 | 71 | 18 | 0 |
| Jun | 1 | 46 | 52 | 1 | 0 |
| Jul | 3 | 76 | 21 | 0 | 0 |
| Aug | 5 | 83 | 12 | 0 | 0 |
| Sep | 3 | 77 | 20 | 0 | 0 |
| Oct | 1 | 60 | 39 | 0 | 0 |
| Nov | 0 | 40 | 59 | 1 | 0 |
| Dec | 0 | 13 | 74 | 13 | 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 Jamestown is typically breezy, near 26 km/h, and varies moderately with the seasons.
The windier part of the year lasts 5.9 months, from around May 30 to Nov 25. The windiest month is August, averaging about 28 km/h (breezy).
The calmer part of the year runs from around Nov 26 to May 29, with January the calmest month at about 24 km/h.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 24 | 23 | 25 | 25 | 25 | 26 | 27 | 28 | 28 | 28 | 26 | 24 |
| Feels | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 24 | breezy |
| Feb | 23 | breezy |
| Mar | 25 | breezy |
| Apr | 25 | breezy |
| May | 25 | breezy |
| Jun | 26 | breezy |
| Jul | 27 | breezy |
| Aug | 28 | breezy |
| Sep | 28 | breezy |
| Oct | 28 | breezy |
| Nov | 26 | breezy |
| Dec | 24 | breezy |
Best time to visit Jamestown
To characterize how pleasant the weather is in Jamestown throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late December, Jamestown is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, Jamestown suits general outdoor tourist activities for most of the year, with a peak score in the third week of February.
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) | 8.6 | 8.8 | 8.7 | 8.6 | 8.3 | 7.9 | 7.7 | 7.4 | 7.3 | 7.4 | 7.7 | 8.2 |
| Rating | ideal | ideal | ideal | ideal | ideal | ideal | ideal | good | good | good | ideal | ideal |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 8.6 | ideal |
| Feb | 8.8 | ideal |
| Mar | 8.7 | ideal |
| Apr | 8.6 | ideal |
| May | 8.3 | ideal |
| Jun | 7.9 | ideal |
| Jul | 7.7 | ideal |
| Aug | 7.4 | good |
| Sep | 7.3 | good |
| Oct | 7.4 | good |
| Nov | 7.7 | ideal |
| Dec | 8.2 | ideal |
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 Jamestown for hot-weather activities is from early January to late May, with a peak score in the first week of March.
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 Jamestown, 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.
Jamestown packs about the same all year — highs hold near 24°C. Across the year the things worth having are light clothes, sun protection and a windbreaker.
In March, Jamestown sees daytime highs around 24°C and nights near 24°C. Pack sun protection. Worth having: light clothes and a windbreaker.
Sea temperature near Jamestown
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea offshore is warmest in March at about 25°C and coldest in October near 20°C.
The water stays above 20°C all year — warm enough for a swim any month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 23 | 24 | 25 | 25 | 24 | 23 | 22 | 21 | 20 | 20 | 21 | 22 |
| Comfort | Refreshing | Warm | Warm | Warm | Refreshing | Refreshing | Refreshing | Refreshing | Refreshing | Refreshing | Refreshing | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 23 | Refreshing |
| Feb | 24 | Warm |
| Mar | 25 | Warm |
| Apr | 25 | Warm |
| May | 24 | Refreshing |
| Jun | 23 | Refreshing |
| Jul | 22 | Refreshing |
| Aug | 21 | Refreshing |
| Sep | 20 | Refreshing |
| Oct | 20 | Refreshing |
| Nov | 21 | Refreshing |
| Dec | 22 | Refreshing |
UV index (midday) in Jamestown 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 Jamestown peaks around January 20 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 21 at about 8 (very high).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 14 | 13 | 13 | 11 | 9 | 8 | 8 | 8 | 10 | 11 | 13 | 12 |
| Level | Extreme | Extreme | Extreme | Extreme | Very high | Very high | Very high | Very high | Very high | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 14 | Extreme |
| Feb | 13 | Extreme |
| Mar | 13 | Extreme |
| Apr | 11 | Extreme |
| May | 9 | Very high |
| Jun | 8 | Very high |
| Jul | 8 | Very high |
| Aug | 8 | Very high |
| Sep | 10 | Very high |
| Oct | 11 | Extreme |
| Nov | 13 | Extreme |
| Dec | 12 | Extreme |
Average hourly UV index in Jamestown
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 8.5 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) | 8.5 | 8 | 8 | 7.5 | 6.5 | 6 | 6.5 | 6.5 | 7.5 | 7.5 | 8 | 8.5 |
| UV ≥ 6 (h/day) | 7 | 6.5 | 6.5 | 5 | 4 | 3.5 | 3.5 | 4 | 5 | 5.5 | 6 | 6.5 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 8.5 | 7 |
| Feb | 8 | 6.5 |
| Mar | 8 | 6.5 |
| Apr | 7.5 | 5 |
| May | 6.5 | 4 |
| Jun | 6 | 3.5 |
| Jul | 6.5 | 3.5 |
| Aug | 6.5 | 4 |
| Sep | 7.5 | 5 |
| Oct | 7.5 | 5.5 |
| Nov | 8 | 6 |
| Dec | 8.5 | 6.5 |
Growing season
Jamestown 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 | 100 | 100 | 100 | 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 | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 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. Jamestown banks about 4,138 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around March.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 384 | 379 | 432 | 405 | 388 | 338 | 316 | 294 | 278 | 290 | 296 | 340 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 384 |
| Feb | 379 |
| Mar | 432 |
| Apr | 405 |
| May | 388 |
| Jun | 338 |
| Jul | 316 |
| Aug | 294 |
| Sep | 278 |
| Oct | 290 |
| Nov | 296 |
| Dec | 340 |
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.
Jamestown receives about 5.6 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.8 and 7.1 kWh/m².
The brighter stretch of the year lasts 6.3 months, from around Sep 30 to Apr 9. The brightest month is January, averaging about 7.1 kWh/m² (intense).
The dimmest month is June, down near 3.9 kWh/m² — roughly 45% less than the January peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 7.1 | 6.9 | 6.3 | 5.4 | 4.5 | 3.9 | 4.0 | 4.5 | 5.3 | 5.9 | 6.6 | 7.0 |
| Level | Intense | Intense | Intense | Bright | Bright | Moderate | Bright | Bright | Bright | Bright | Intense | Intense |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 7.1 | Intense |
| Feb | 6.9 | Intense |
| Mar | 6.3 | Intense |
| Apr | 5.4 | Bright |
| May | 4.5 | Bright |
| Jun | 3.9 | Moderate |
| Jul | 4.0 | Bright |
| Aug | 4.5 | Bright |
| Sep | 5.3 | Bright |
| Oct | 5.9 | Bright |
| Nov | 6.6 | Intense |
| Dec | 7.0 | Intense |
Where is Jamestown?
Jamestown sits at 15.9°S, 5.7°W, 10 m above sea level, in Saint Helena. The nearest listed city is Tômbua, 1,878 km away.
Topography around Jamestown
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Jamestown.
Within 3 km, the terrain around Jamestown has significant variations in elevation — a maximum elevation change of 581 m around an average of 155 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 795 m; within 80 km, large variations in elevation — a maximum elevation change of 766 m.
The land around Jamestown is covered by water (44%) and shrubs (27%) within 3 km, water (85%) within 16 km, and water (97%) within 80 km.
Saint Helena travel facts
- Power plugs
- Type G
- 230 V · 50 Hz
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 Jamestown (-15.9249°, -5.7182°, elevation 10 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).