5°C (41°F) is very cold water for unacclimatised swimmers, especially if you're used to swimming in 18°C (64°F). You could probably manage a short dip (1 or 2 mins), but I would not plan for longer than than.

A couple of years ago I swam outdoors from May-November in my local lido. The water temperature peaked at ~20°C (~68°F) in August, and by the start of November was 8°C (44°F). In the summer I was swimming up to 5000m, but as the temperature dropped I reduced this down. By the end was I only doing 400m.

The exact perception of the cold depends on a lot of things: size, weight, fat, gender, cold water acclimatisation, etc etc. Personally, while swimming below 10°C (50°F) I would feel a burning sensation from the cold, eventually followed by creeping numbness in the hands and feet. I would get out before feeling cold in my core. About 5-10 minutes after getting out I would sometimes shiver for a few minutes due to afterdrop (when your body temperature drops further after getting out of the water). After about an hour I would start to warm up again.

A few tips if you are still considering it:

• Just plan for a dip the first time you go in, don't expect to spend more than a couple of minutes in the water.
• Get in slowly to manage cold shock. Splash water on your face before putting your head under, and expect the mammalian diving reflex.
• Wear 2x swim hats to provide some extra insulation, and when getting dressed take them off last to keep the heat in
• Have a hot drink ready for when you get out
• Pile your clothes in the order you put them on, and make sure everything is the right way round. Trying to turn a jumper inside out with damp numb hands is surprisingly tricky! Take more layers than you think you'll need and a wooly hat.
• Plan your entry and exit to the water. Don't get into the water before you know how you can get out of it.
• Take a friend who can call for help and .

I would also check out LoneSwimmer, which is a great cold water swimming blog with lots of advice. Cold water swimming is a great sport, and I definitely would encourage you to get into it, but 5°C (41°F) is probably too cold a starting point.

5°C (41°F) is very cold water for unacclimatised swimmers, especially if you're used to swimming in 18°C (64°F). You could probably manage a short dip (1 or 2 mins), but I would not plan for longer than than.

A couple of years ago I swam outdoors from May-November in my local lido. The water temperature peaked at ~20°C (~68°F) in August, and by the start of November was 8°C (44°F). In the summer I was swimming up to 5000m, but as the temperature dropped I reduced this down. By the end was I only doing 400m.

The exact perception of the cold depends on a lot of things: size, weight, fat, gender, cold water acclimatisation, etc etc. Personally, while swimming below 10°C (50°F) I would feel a burning sensation from the cold, eventually followed by creeping numbness in the hands and feet. I would get out before feeling cold in my core. About 5-10 minutes after getting out I would sometimes shiver for a few minutes due to afterdrop (when your body temperature drops further after getting out of the water). After about an hour I would start to warm up again.

A few tips if you are still considering it:

• Take a friend - they can call for help if you get into difficulty and help you warm up/get dressed etc.
• Just plan for a dip the first time you go in, don't expect to spend more than a couple of minutes in the water.
• Get in slowly to manage cold shock. Splash water on your face before putting your head under, and expect the mammalian diving reflex.
• Wear 2x swim hats to provide some extra insulation, and when getting dressed take them off last to keep the heat in
• Have a hot drink ready for when you get out
• Pile your clothes in the order you put them on, and make sure everything is the right way round. Trying to turn a jumper inside out with damp numb hands is surprisingly tricky! Take more layers than you think you'll need and a wooly hat.
• Plan your entry and exit to the water. Don't get into the water before you know how you can get out of it.

I would also check out LoneSwimmer, which is a great cold water swimming blog with lots of advice. Cold water swimming is a great sport, and I definitely would encourage you to get into it, but 5°C (41°F) is probably too cold a starting point.

5°C is very cold water for unacclimatised swimmers, especially if you're used to swimming in 18°C. You could probably manage a short dip (1 or 2 mins), but I would not plan for longer than than.

A couple of years ago I swam outdoors from May-November in my local lido. The water temperature peaked at ~20°C in August, and by the start of November was 8°C. In the summer I was swimming up to 5000m, but as the temperature dropped I reduced this down. By the end was I only doing 400m.

The exact perception of the cold depends on a lot of things: size, weight, fat, gender, cold water acclimatisation, etc etc. Personally, while swimming below 10°C I would feel a burning sensation from the cold, eventually followed by creeping numbness in the hands and feet. I would get out before feeling cold in my core. About 5-10 minutes after getting out I would sometimes shiver for a few minutes due to afterdrop (when your body temperature drops further after getting out of the water). After about an hour I would start to warm up again.

A few tips if you are still considering it:

• Just plan for a dip the first time you go in, don't expect to spend more than a couple of minutes in the water.
• Get in slowly to manage cold shock. Splash water on your face before putting your head under, and expect the mammalian diving reflex.
• Wear 2x swim hats to provide some extra insulation, and when getting dressed take them off last to keep the heat in
• Have a hot drink ready for when you get out
• Pile your clothes in the order you put them on, and make sure everything is the right way round. Trying to turn a jumper inside out with damp numb hands is surprisingly tricky! Take more layers than you think you'll need and a wooly hat.
• Plan your entry and exit to the water. Don't get into the water before you know how you can get out of it.
• Take a friend who can call for help and .

I would also check out LoneSwimmer, which is a great cold water swimming blog with lots of advice. Cold water swimming is a great sport, and I definitely would encourage you to get into it, but 5°C is probably too cold a starting point.

5°C (41°F) is very cold water for unacclimatised swimmers, especially if you're used to swimming in 18°C (64°F). You could probably manage a short dip (1 or 2 mins), but I would not plan for longer than than.

A couple of years ago I swam outdoors from May-November in my local lido. The water temperature peaked at ~20°C (~68°F) in August, and by the start of November was 8°C (44°F). In the summer I was swimming up to 5000m, but as the temperature dropped I reduced this down. By the end was I only doing 400m.

The exact perception of the cold depends on a lot of things: size, weight, fat, gender, cold water acclimatisation, etc etc. Personally, while swimming below 10°C (50°F) I would feel a burning sensation from the cold, eventually followed by creeping numbness in the hands and feet. I would get out before feeling cold in my core. About 5-10 minutes after getting out I would sometimes shiver for a few minutes due to afterdrop (when your body temperature drops further after getting out of the water). After about an hour I would start to warm up again.

A few tips if you are still considering it:

• Just plan for a dip the first time you go in, don't expect to spend more than a couple of minutes in the water.
• Get in slowly to manage cold shock. Splash water on your face before putting your head under, and expect the mammalian diving reflex.
• Wear 2x swim hats to provide some extra insulation, and when getting dressed take them off last to keep the heat in
• Have a hot drink ready for when you get out
• Pile your clothes in the order you put them on, and make sure everything is the right way round. Trying to turn a jumper inside out with damp numb hands is surprisingly tricky! Take more layers than you think you'll need and a wooly hat.
• Plan your entry and exit to the water. Don't get into the water before you know how you can get out of it.
• Take a friend who can call for help and .

I would also check out LoneSwimmer, which is a great cold water swimming blog with lots of advice. Cold water swimming is a great sport, and I definitely would encourage you to get into it, but 5°C (41°F) is probably too cold a starting point.