Via The Flight Deal, flights to Europe are heavily discounted for September and October 2016 travel. They list San Francisco round-trip to Istanbul for just $425 as an example.
I found Chicago to London non-stop, round-trip on Virgin Atlantic for $583 September 24 to October 1, 2016.
I’m also seeing Washington, DC, round-trip to Barcelona for ~$595 on United Airlines and Air Canada in October 2016.
Here’s how to find the deal.