Daily departures at this price open up in late April and are valid through June and then again from late-August until the end of November. There is no minimum stay required and checked baggage is included, which makes this deal much better than what other airlines are offering in the price range. Other than peak summer July and early August trips this fare is wide open and easily booked on the Copa website.
As an example below, I found tickets departing BOS on Wednesday, August 28 and returning from SJO on Wednesday, September 4, 2019. Perfect for a weeklong exotic escape over the Labor Day extended weekend.
Need a room in San Jose? Here's what we found for the listed dates on Hotelwatchdog.