It’s one thing to see sub-$400 transatlantic roundtrips in Winter, as great as that is, but we’re now starting to see fares like this for summer which is peak time to visit Europe and when you normally see the cost of European coach airfares skyrocket. What could be better than Paris in summer for less than $350?

Air Canada and Swiss have fares in the high $300s between Miami and Paris, for instance:

This is an insanely low $37 base fare in each direction, so you know it doesn’t really get much cheaper than this.

Except… when it does. Here’s an Air Canada trip via Toronto (United Airlines codeshare) found using airfare metasearch site Momondo that’s even cheaper:

Key things to know about this fare:

• You can fly to Europe on a Sunday through Wednesday. Travel is permitted under this fare April 1 through May 11 or August 6 through August 28, September 3 through September 27.

• You can fly back from Europe on a Monday through Thursday, April 1 through June 2 or August 24 through September 30.

• Minimum stay requires travel no earlier than the first Sunday after arrival, but in practice it’s the first Monday since Sunday travel isn’t allowed with this fare.

Tickets must be issued by February 16, but it’s unlikely the fare will last that long – the lowest airfares wind up as flash sales – here’s why.

Meanwhile a fare with similar rules is available on American Airlines for $396:

You’re not going to upgrade the Air Canada or Swiss fares, but American AAdvantage systemwide upgrades can be used even on this $396 roundtrip Miami – Paris fare when traveling on American.

(HT: Loyalty Traveler)