Climate and monthly weather forecast
Jamestown, Saint Helena, Ascension and Tristan da Cunha

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The valley town of Jamestown in Saint Helena, with a view of mountain slopes on both sides
The valley town of Jamestown in Saint Helena, with a view of mountain slopes on both sides

The climate of Jamestown

Jamestown harbors a tropical rainforest climate according to the Köppen climate classification. This island town, nestled in the middle of the South Atlantic Ocean, sees warm, tropical conditions, punctuated by plentiful rainfall throughout the year.

Upon inspection of the climate data, one sees that the temperatures largely remain consistent, with little fluctuation. The highest average recorded temperatures peak at 28°C (82.4°F), typically in March. Meanwhile, the cooler months, especially from June to September, see a slight dip in temperatures, with averages ranging from 22°C (71.6°F) to 23°C (73.4°F). Nighttime lows follow a similar pattern, with the chilliest nights occurring from June to September, recording averages of 17°C (62.6°F). Conversely, the warmer months, particularly from January to April, experience lows standing at around 21°C (69.8°F) to 22°C (71.6°F).

In terms of precipitation, Jamestown's tropical status is reinforced by an abundance of rainfall. The wettest period comes around March, with an average rainfall of 20mm (0.79"). Surprisingly, rainfall tends to significantly decline in November, with barely any to no rainfall, followed by December's 3mm (0.12") precipitation. The maximum daylight also fluctuates over the year; the island basking in approximately 13.1 hours of daylight at the year-end, while the shortest days, between June and July, experiencing around 11.2 to 11.3 daylight hours.

The best time to visit Jamestown

Considering the temperate, consistent climate, there isn’t necessarily a specific "best" time to visit Jamestown. That said, those comfortable with warmer climates would find the period from January to April most accommodating. During this period, daily highs stand at an inviting 27°C (80.6°F) to 28°C (82.4°F), with lows between 21°C (69.8°F) and 22°C (71.6°F). Meanwhile, the rainfall remains relatively subdued, making for comfortable, warm days, without the concern of frequent rains.

The worst time to visit Jamestown

Despite the warm, tropical allure, potential visitors should be wary during the month of March. Despite presenting a high average temperature of 28°C (82.4°F), the amount of rainfall also tends to peak at 20mm (0.79") during this month. The increased humidity and a relatively high likelihood of encountering wet weather might make it less desirable for some tourists.

Spring weather in Jamestown

In Jamestown, spring months span from September to November and usually indicate a transition towards the slightly warmer side of the climate spectrum. Throughout this period, average high temperatures gradually increase from 22°C (71.6°F) to 23°C (73.4°F) in November. Despite this upward trend in temperatures, rainfall significantly decreases, with November standing out as the driest month, reporting virtually no rainfall.

Summer weather in Jamestown

The summer months of December through February see the temperatures at a comfortable average between 23°C (73.4°F) and 27°C (80.6°F). Often, the temperatures hardly dip below 18°C (64.4°F) to 21°C (69.8°F) at night. Rainfall is minimal to moderate, ensuring relatively dry, warm conditions that define the summer experience in Jamestown.

Autumn weather in Jamestown

Experiencing autumn in Jamestown from March to May entails seeing an average high temperature of 27°C (80.6°F) to 24°C (75.2°F). Minimum temperatures never fall below 21°C (69.8°F). While March records the highest rainfall of the year at 20mm (0.79"), it gradually decreases to a moderate 18mm (0.71") by May.

Winter weather in Jamestown

Winter, spanning from June to August, reveals cooler climes. Temperatures vary from 22°C (71.6°F) to 23°C (73.4°F) during the day while plunging down to 17°C (62.6°F) at night. Despite being slightly cooler than other months, rainfall remains moderate with averages measuring between 8mm (0.31") and 10mm (0.39"), ensuring a distinctly mild, tropical winter in Jamestown.

Weather in January

Known as the heart of the Southern Hemisphere summer, January is typically hot in Jamestown, Saint Helena, Ascension, and Tristan da Cunha. The warmth is balanced against the fresh ocean breezes that people often associate with the quintessential island experience. Weather in January »

Weather in February

In February, the climate remains quite consistent with that of the previous month, showing a typical continuity of the summer season. The days continue to be warm and long, inviting outdoor activities and beach ventures. The weather conditions do not change dramatically, ensuring a steady flow of tourists during this period. Weather in February »

Weather in March

The tropical influence over the March weather is accompanied by an escalation of rainfall up to 20mm (0.79") while sustaining the previous months' highest temperature at 28°C (82.4°F). This is a period of transition, shifting from the continuous heat of summer towards the early signs of the cooler season. Weather in March »

Weather in April

Moving into the autumn season, April ushers in a noticeable decline in temperatures and rainfall in Jamestown, Saint Helena, Ascension, and Tristan da Cunha. The shift in temperature begins to signal the onset of cooler times while exhibiting a modest decrease in precipitation. Weather in April »

Weather in May

May signifies the true arrival of autumn in this part of the world, bringing in the lower temperatures and noticeable changes to the local flora. Prevalent in this season is the blend of both sunshine and rainfall, creating an array of rainbows that dot the overhead skies. Weather in May »

Weather in June

When June arrives, residents and visitors have fully embraced the cooler conditions in Jamestown and its associated islands. Outdoor enthusiasts find the atmosphere optimal for exploration and terrain trekking without the scorching heat of the summer months. Weather in June »

Weather in July

July’s weather casts a calm and tranquil vibe over Jamestown, Saint Helena, Ascension, and Tristan da Cunha. It's a time where locals welcome the intermingling of cold fronts and clear skies. While rainfall becomes more frequent, reaching 8mm (0.31"), the region's natural allure remains undiminished for the wildlife and visitors. Weather in July »

Weather in August

Weather in August evokes a sense of ever-changing meteorological dynamics as the transition from winter to spring begins. Sporadic showers intersperse with warm spells, bestowing awe-inspiring landscapes. The potential for incredible photography is high during this period, courtesy of the contrasting elements of sun, rain, and unique flora. Weather in August »

Weather in September

September ushers a new lease of life to these South Atlantic islands, flourishing with the onset of spring. A gentler 5mm (0.2") rainfall allows the petals to unfurl and the leathery leaves to shine in verdant hues. Appearances of rainbows become more frequent, curving over the island landscape against the backdrop of fewer scattered clouds. Weather in September »

Weather in October

October is routinely distinguished by its flowers' full bloom and a barely-there 3mm (0.12") rainfall. The pleasant weather, coupled with wandering wildlife, creates an intriguing spectacle for nature lovers. Mild nights, warm days, and gentle breezes are the hallmarks of October in Jamestown and its surrounding islands. Weather in October »

Weather in November

In November, the fine weather shows no signs of cessation, making the island an appealing destination for visitors. The climate defines the quintessential pre-summer conditions, marked by sunshine and long daylight hours. The minimal rainfall of 0mm (0") assists the transition from spring to summer, providing the perfect blend of warmth and light. Weather in November »

Weather in December

As the chapter of the year comes to a close, Jamestown, Saint Helena, Ascension, and Tristan da Cunha bask in the full glow of the Southern Hemisphere’s summer. The weather in December is typically warm and inviting, characterized by longer days and higher temperatures soaring up to 24°C (75.2°F). Weather in December »

Frequently asked questions

How many days does it rain in Jamestown?

Throughout the year, in Jamestown, there are 40.7 rainfall days, and 113mm (4.45") of precipitation is accumulated.

What is the warmest month in Jamestown?

March is the month when Jamestown, Saint Helena, Ascension and Tristan da Cunha, experiences its warmest temperatures, averaging a high of 28°C (82.4°F) and a low of 22°C (71.6°F).

What is the wettest month in Jamestown?

March is the month with the most rainfall. Rain falls for 5 days and accumulates 20mm (0.79") of precipitation.

What is the month with the shortest days in Jamestown?

With an average of 11h and 12min of daylight, June has the shortest days of the year.

What is the coldest month in Jamestown?

July through September in Jamestown, Saint Helena, Ascension and Tristan da Cunha, are characterised by lowest temperatures, with an average high of 22°C (71.6°F).

What is the driest month in Jamestown?

The only month without rainfall is November.

When does it rain in Jamestown?

Months with rainfall in Jamestown are January through October and December.

When are the longest days in Jamestown?

With an average of 13h and 6min of daylight, December has the longest days of the year in Jamestown, Saint Helena, Ascension and Tristan da Cunha.

Is there Daylight Saving Time (DST) in Jamestown?

Jamestown, Saint Helena, Ascension and Tristan da Cunha, does not utilize Daylight Saving Time (DST). GMT timezone is used over the entire year.

Average temperature
Jamestown, Saint Helena, Ascension and Tristan da Cunha

Average temperature - Jamestown, Saint Helena, Ascension and Tristan da Cunha

The warmest month (with the highest average high temperature) is March (28°C).
The months with the lowest average high temperature are July, August and September (22°C).

The month with the highest average low temperature is March (22°C).
The coldest months (with the lowest average low temperature) are July, August and September (17°C).

Average rainfall
Jamestown, Saint Helena, Ascension and Tristan da Cunha

Average rainfall - Jamestown, Saint Helena, Ascension and Tristan da Cunha

The wettest month (with the highest rainfall) is March (20mm).
The driest month (with the least rainfall) is November (0mm).

Average rainfall days
Jamestown, Saint Helena, Ascension and Tristan da Cunha

Average rainfall days - Jamestown, Saint Helena, Ascension and Tristan da Cunha

The month with the highest number of rainy days is July (8 days).
The month with the least rainy days is November (0 days).

Average daylight
Jamestown, Saint Helena, Ascension and Tristan da Cunha

Average daylight - Jamestown, Saint Helena, Ascension and Tristan da Cunha

The month with the longest days is December (Average daylight: 13h and 6min).
The month with the shortest days is June (Average daylight: 11h and 12min).

Jamestown, Saint Helena, Ascension and Tristan da Cunha

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