"It's windy in here" can only be used when you are inside some sort of structure or enclosure. An arena, a partially enclosed building or maybe a house (when the windows are open). "It's windy here" can also be used this way, but more often you use it when you are outside in the open air (not within or inside some building or enclosure)

You would only say 'in here' if you were inside. So, if somebody had left the windows open or the air conditioning was creating a strong breeze you might say "It's windy in here". However if you were outside, as you would normally be when commenting like this you would say "It's windy here"

There are a couple of clear and helpful responses from two of the best native English speaker answerers here. Both explain the difference between these two sentences and either of these should have been the 'Best Answer'. Yet the OP seems to have ignored them, choosing instead to thank the one person who has given an unhelpful/incomplete/wrong answer and to nominate that as her Best Answer. Why? The only reason I can think of is that Tetiana closed this discussion as soon as she saw her first answer, not realising that Bramwell and Greg were in the process of writing much better explanations. A word of advice: Never choose 'Best Answer' after only one response. Many of the answers that appear here are inaccurate and misleading, so it is always worth waiting to see if any more come along.

It‘s windy here’

"it's windy in here" is commonly used if you're within an enclosure like a tunnel, as to say "it's windy inside here"