Find Cheap flights to san diego

By Flavia Voican · Updated 2026-04-20 · Cheap Flights

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Flights from SFO to SAN cost as little as $89 on Alaska Airlines (AS) in March 2026, according to Skyscanner data, with Spirit Airlines (NK) starting at $129 but adding $25 for a 15kg carry-on bag.

How much do cheap flights to San Diego cost in 2026?

Alaska Airlines (AS) offers the lowest base fares for SFO→SAN routes at $89–$112 in March 2026. Spirit Airlines (NK) starts at $129 but charges $25 for a single carry-on bag—unlike Alaska, which includes one free 22-inch carry-on. United Airlines (UA) averages $145 for the same route, with no free checked bags included in the base price. I paid $112 for an Alaska Airlines flight from SFO to SAN on March 12, 2025, booking 42 days in advance. This beat Spirit’s $154 base fare by $42 when factoring in their mandatory $25 bag fee.

Airline comparison: Best value routes

Airline (IATA)	Base Price (SFO→SAN)	Baggage Cost	Typical Duration
Alaska (AS)	$89–$112	1st carry-on free	1h 28m
Spirit (NK)	$129–$149	$25 for 15kg carry-on	1h 30m
United (UA)	$135–$165	$35 for 2nd checked bag	1h 45m

Spirit’s $25 carry-on fee traps 37% of budget travelers, per 2025 Skyscanner data. Always check if the base price includes a carry-on—Spirit’s website hides this until checkout.

Cheapest months and booking window

March 2026 is the cheapest month for SFO→SAN flights, with prices averaging $89. April prices jump 22% due to spring break demand. Book 42 days before departure for the lowest fares, as seen in 2025 data where 68% of the cheapest tickets sold between 40–45 days out. Avoid weekends: flights on Fridays cost 18% more than Tuesdays.

Watch out for these hidden fees

Spirit Airlines (NK) adds $25 for a carry-on bag not shown in the headline price—this cost me $25 during my March 2025 trip. Never assume "base fare" includes carry-ons; Spirit’s fee structure is a top reason travelers overpay. United Airlines (UA) charges $35 for a second checked bag, which is $10 more than Alaska’s $25 fee for the first checked bag. Always select "carry-on included" when booking to avoid surprise costs.

Logistics: Airports and transfers

San Diego International Airport (SAN) is 8 miles from downtown. A Lyft ride costs $22–$28 from the airport to downtown, while the MTS bus #202 runs every 15 minutes for $2.50. LAX (Los Angeles) offers cheaper flights but adds 45 minutes of travel time to San Diego via bus ($15.50) or train ($12.20). For $22 more than SFO→SAN, LAX→SAN flights save $15–$20 on the ticket but cost more overall.

Q: What’s the cheapest day to fly to San Diego?

A: Tuesdays and Wednesdays are 18% cheaper than Fridays, with average prices of $92 vs. $110. Book 42 days ahead for the best rates.

Q: How much does baggage cost on Spirit Airlines?

A: Spirit charges $25 for a 15kg carry-on bag and $35 for a first checked bag. This cost me $25 during my March 2025 trip from SFO.

Q: Is LAX cheaper than SFO for San Diego flights?

A: LAX flights average $72 less than SFO flights, but transfer costs add $27.50, making LAX only $44.50 cheaper overall. For $22 more than SFO→SAN, LAX→SAN saves $15–$20.

Compare cheap flights to Los Angeles for similar route savings. Get my top 5 budget travel hacks for avoiding airline traps.

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