One of the essential ways to save on airfare from San Diego to St. John's is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the morning could potentially save you up to 15% on airfare.
Flying to your destination on a Sunday can be more expensive, but this shouldn’t discourage you from finding affordable options to get to St. John's. Check prices with Cheapflights to find a great deal for your trip.