According to the calender, Summer started last week, according to  Mother Nature, summer started months ago! Never the less,  if you're looking to take a vacation soon, the travel site Kayak found the best and worst days to find a bargain.

According to Kayak, the cheapest days to travel this summer are Monday, September 3rd and Wednesday, September 19th.  The median price of a domestic flight on those days is $177.

If you want to travel on a weekend, it's a little more expensive.  The best weekend to travel is August 25th, when the median flight is $305.

The most EXPENSIVE weekend to travel is June 30th, which is next weekend.

You could always travel during the week, of course, that's when the tickets are the cheapest.