Climate and monthly weather forecast
Weather in January
In January, the average sea temperature in Portland, United Kingdom, is 9.7°C (49.5°F). Note: Dipping in 9.7°C (49.5°F) at temperatures less than 10°C (50°F) without proper gear can lead to pronounced cold shock and breathing difficulties. Weather in January »
Weather in February
In Portland, United Kingdom, in February, the average water temperature is 9.2°C (48.6°F). Note: Swimming in 9.2°C (48.6°F) is considered dangerous. Weather in February »
Weather in March
March is the month with the coldest seawater in Portland, United Kingdom, with an average sea temperature of 8.8°C (47.8°F). Note: Entering waters of 8.8°C (47.8°F) is life-endangering. Weather in March »
Weather in April
In April, the average sea temperature in Portland, United Kingdom, is 10°C (50°F). Note: Caution: 10°C (50°F) temperatures below 10°C (50°F) during swimming can result in intense cold shock and quickened breathing. Weather in April »
Weather in May
In Portland, United Kingdom, in May, the average water temperature is 11.4°C (52.5°F). Note: Unprotected swimming in 11.4°C (52.5°F) is dangerous due to potential cold shock. Weather in May »
Weather in June
In Portland, United Kingdom, in June, the average water temperature is 13.3°C (55.9°F). Note: One needs to be cautious in 13.3°C (55.9°F) waters. 13°C (55.4°F) is already forbidding, but sub-10°C (14°F) can seriously disrupt your breathing and lead to a frigid shock, considering one's well-being. Weather in June »
Weather in July
In Portland, United Kingdom, the average seawater temperature in July is 15.3°C (59.5°F). Note: Swimming is not a pleasant activity for most individuals in 15.3°C (59.5°F). Weather in July »
Weather in August
In August, the average sea temperature in Portland, United Kingdom, is 16.6°C (61.9°F). Note: When the surface water temperature is 16.6°C (61.9°F), most do not enjoy swimming. Weather in August »
Weather in September
September is the month with the warmest seawater in Portland, United Kingdom, with an average sea temperature of 17.1°C (62.8°F). Note: For most individuals, swimming in 17.1°C (62.8°F) is not enjoyable. Weather in September »
Weather in October
In Portland, United Kingdom, in October, the average water temperature is 16.2°C (61.2°F). Note: Swimming in 16.2°C (61.2°F) does not offer a pleasant experience for most individuals. Weather in October »
Weather in November
In November, the average sea temperature in Portland, United Kingdom, is 14.3°C (57.7°F). Note: Swimming in 14.3°C (57.7°F) is deemed hazardous. Exposure to temperatures below 10°C (50°F) leads to immediate severe cold shock and hyperventilation. Weather in November »
Weather in December
In Portland, United Kingdom, in December, the average water temperature is 11.9°C (53.4°F). Note: Dipping into 11.9°C (53.4°F) below 10°C (50°F) is possible with the right protection; absent that, anticipate cold shock and hampered breathing. Weather in December »
Updated: Feb 8, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What month is the sea coldest in Portland?
March is the month with the coldest seawater in Portland, with an average sea temperature of 8.8°C (47.8°F).
When are the longest days in Portland?
June has the longest days of the year, with an average of 16h and 24min of daylight.
What is the month with the warmest sea water in Portland?
The month with the warmest seawater in Portland is September, with an average sea temperature of 17.1°C (62.8°F).
When is Daylight Saving Time (DST) in Portland?
On Sunday, 27. October 2024, at 2:00 am, Daylight Saving Time ends in Portland, and the time zone changes from BST to GMT. The next Daylight Saving Time starts on Sunday, 30. March 2025, at 1:00 am, and the time zone reverts from GMT to BST.
What is the month with the shortest days in Portland?
December has the shortest days of the year in Portland, United Kingdom, with an average of 8h and 6min of daylight.
Average sea temperature
Portland, United Kingdom
The best month for swimming (with the highest average sea temperature) is September (17.1°C).
The coldest month (with the lowest average sea temperature) is March (8.8°C).
Average daylight
Portland, United Kingdom
- Average daylight in January:
8h and 4min - Average daylight in February:
10h and 1min - Average daylight in March:
11h and 5min - Average daylight in April:
13h and 5min - Average daylight in May:
15h and 3min - Average daylight in June:
16h and 2min
- Average daylight in July:
15h and 5min - Average daylight in August:
14h and 3min - Average daylight in September:
12h and 4min - Average daylight in October:
10h and 4min - Average daylight in November:
9h and 0min - Average daylight in December:
8h and 1min
The month with the longest days is June (Average daylight: 16h and 24min).
The month with the shortest days is December (Average daylight: 8h and 6min).
