If you want to maintain your professional image do not go shorter just because it is summer. Avoid wearing short dresses, especially if you opt to go without pantyhose. Showing too much leg in the office is a sure way to come off as "too much sexy and not enough smarts."
Mini skirts are never acceptable at the office -- even mini skirts with a suit jacket. Save cute skirts like the one above for weekends and after hours when you are not on your employer's clock.
Jean skirts of any length are also too casual for the work place. And, if you want co-workers, clients, and your boss to take your seriously avoid tight skirts, skits with high slits, and skirts that ride up and show too much thigh when you sit down or bend over.
Not sure if a skirt is too short? Ask a friend, your spouse, or bend halfway over and look in the mirror. If you can see the upper part of your thighs or panties -- it is too short!