4 hr 5 min is the shortest flight time from Chicago to San Diego.

The cheapest days to fly are usually in January. Typical prices range from $115 to $210.

The best round-trip deal recently found on Google Flights from Chicago to San Diego was with Spirit from $127. The best one-way deal was with Spirit from $55.

There are direct flights from Chicago to San Diego on a daily basis.

Southwest, United and American fly direct from Chicago to San Diego.

The cheapest round-trip flight from Chicago to San Diego starts at $127 from Mon, Aug 19 to Tue, Aug 27. The cheapest one-way flight starts at $55 and departs on Mon, Aug 26.

Jun–Aug is when most people visit San Diego, where the weather's temperate year-round. Beaches are less crowded Dec–Feb, which bring cooler temperatures but brighter sun. Whale-watching season is from mid-Dec–mid-Mar. Major annual events include Comic-Con International (Jul), a massive comic book convention with workshops and film screenings. Fleet Week (autumn) is a large military appreciation event featuring Navy ship tours, an air show and more.

It's easy to use Google Flights to find the cheapest days to fly from Chicago to San Diego.
Just click the Departure label near the top of the page to open the calendar. Choose a start date and a return date to see how the round-trip fare changes on those specific days.
Adjust the trip type to see one-way fares. The cheapest available flights are highlighted and easy to spot. Once you settle on dates, click the Search button to see flight options and book the deal.

You can also turn on price tracking to get alerts if the price changes for a route or flight.