The air temperature can give you a false sense of security and if hot can actually make the water feel colder. Likewise if cold can make the water feel comfortable but will cool you down very quickly when you get out.
Direction of the wind is going to be either onshore, offshore or cross shore. Strength and temperature of the wind can also have a cooling effect on your body if blowing strong and cold. Consider changing in a sheltered spot as near to the water as possible.
Monitor the weather condition. If a hot sunny day you might feel like staying in longer than if a freezing hailing day.
Water temperatures can fluctuate daily depending on the weather. The less time the sun has given heat to the water the colder it will be. February/March is usually the coldest months in the UK’s waters.
The height of the tide may dictate how long you can stay in; if too high or low it may expose hidden dangers.
Sea conditions play a massive part. Diving under the waves and swimming in between sets uses a lot of energy. If it’s calm and you are gently bobbing around you won’t use so much but may get just as cold as not moving much.
Swim time may be depicted by how much time you have. Is it a lunchtime dip or an after work swim? Allow yourself plenty of time to get changed and warm up before driving home. If you are swimming with a friend do you need to get out with them and are they restricted for time.
How you feel both physically and mentally will have an impact on the length of time you stay in the water. If you are already cold you may feel you don’t want to stay in for long whereas if you are hot and it’s a lovely summers day you may not want to get out!!! One day you might go in for 10 minutes the next day 5. Note how long it takes you to warm up in various conditions and soon you will appreciate how you feel. It is better to get out sooner than to stay in too long and get cold. Remember your core continues to cool down at least 20 minutes after you have left the water.
SO IN SHORT STAY IN AS LONG AS YOU WANT TO.
IT IS TOTALLY UP TO THE INDIVIDUAL AND YOU SHOULD LEARN TO LISTEN TO YOUR OWN BODY.
NEVER STAY IN THE WATER WHEN YOU ARE SHIVERING, HAVE STOPPED SHIVERING, CAN’T STRING A SENTENCE TOGETHER OR FEEL UNWELL. IF YOU EXPERIENCE ANY OF THESE ENSURE SOMEONE STAYS WITH YOU AND MONITORS YOU UNTIL YOU FEEL BACK TO NORMAL.
BE MINDFUL OF NOT PRESSURISING ANYONE TO STAY IN LONGER THAN THEY WANT.