"Mid" here means "mid point" or "middle point." Or "halfway point." So "mid-February" means 14 February. But when used with a month, it does not have to mean the exact halfway point. But it would be close. So, "mid-February" means 14 February or close to 14 February (say 12-16 February). It does not mean the "middle third" of February (10-20 February). "Mid-day" means noon. (Not 11 am or 1 pm). Mid-night means 12am.