ALL months have 28 days.
Why does February have 28 days?
If it had one less, we'd never get to March! If it had one more we'd have permanent leap years! (or March would crash into April - heaven knows what would happen!)
Because someone wanted a short month
Don't forget that this year, February has 29 days!
Because otherwise, you'd have to shorten the other months, and that would get confusing.
because of a leap year.