Jamestown Temperature by Month

The average annual maximum temperature in Jamestown, Saint Helena is 23°C (73°F), with little variation between seasons. This page covers monthly averages, day-night differences, and how Jamestown compares to cities worldwide.

Jamestown enjoys a stable climate with temperatures staying pretty much the same throughout the year. Maximum daytime temperatures range from a pleasant 21°C (70°F) in September to a comfortable 26°C (79°F) in March. Nights are consistently cool, with lows between 24°C (75°F) and 19°C (66°F).

The chart below illustrates the average maximum day and minimum night temperatures in Jamestown by month:

The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM.

The chart below shows the average temperature throughout the year:

Jamestown's average annual maximum temperature is 23°C (73°F). To put that in context, here's how it compares to a few well-known destinations:

Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.

Reykjavík, Iceland averages 9°C (48°F) a year, mild summers by Icelandic standards, but cold winters and frequent wind.

Seoul, South Korea averages 18°C (64°F) a year, with four clear seasons, cold winters, and hot humid summers.

Tokyo, Japan averages 21°C (70°F) a year, with hot summers, cool winters, and a well-defined cherry blossom spring.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In Jamestown, September is the coolest month, with average highs of 21°C (70°F) and humidity around 75%, considered high. In March, the warmest month, temperatures average 26°C (79°F) with 64% humidity, conditions that feel high. For a full picture, see our humidity page.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained, so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.

For more on Jamestown's weather, including monthly rainfall, sunshine hours, and humidity, visit our Jamestown climate page.