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Hello,
How do you ask a friend if he/she is OK about temperature in room or outside when it can be cold? You hope that he/she don't feel bad.
Are not you cold?
Don't you freeze?
Is not it cold for you?
?
Thanks
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"Are you warm enough?" would also be natural.
Comments  
Hi,
Here are some examples.

Questions
Isn't it cold today?
Isn't it cold in here?
Are you cold?
Aren't you freezing?
Would you like me to turn up the heat (BrE: heating)?

Answers
It's freezing cold.
I'm freezing.
I'm cold.
Please turn up the heat. Thanks.

Regards
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Thanks a lot, Regards
 khoff's reply was promoted to an answer.
Thanks, knoff
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