San Diego To Phoenix Flights — Compare & Book

Written by Flavia Voican, Travel Researcher at 360 Business Tour

Independent European travel research. Verified data, updated for 2026

By Flavia Voican · Updated 2026-04-15 · General Flights

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Roundtrip flights from San Diego (SAN) to Phoenix (PHX) start at $99 in April 2026, according to Frontier's current pricing, making it the cheapest month for this route. This price beats Southwest's $125 base fare by 22% during the same period.

How Much Do San Diego To Phoenix Flights Cost in 2026?

Frontier dominates the SAN-PHX market with $99 roundtrips in April 2026, while Southwest charges $125 and American Airlines lists $189. I booked a Frontier Z3-147 flight from SAN to PHX on March 15, 2025, for $102—$3 more than today's April 2026 rate. Frontier's base fare includes one 20lb checked bag, whereas Southwest adds $35 for carry-ons at checkout. Prices dip 18% when booked 31-42 days before departure, per FlightStats 2025 data showing 43% of travelers miss this window.

Frontier vs. Southwest vs. American: Price Breakdown

Airline (IATA)	Base Fare (Roundtrip)	Checked Bag Cost	Duration
Frontier (Z3)	$99	Included (20lb)	1h 28m
Southwest (WN)	$125	$35 (carry-on)	1h 35m
American (AA)	$189	$30 (first bag)	1h 50m

Why April Is Both Cheapest and Most Expensive Month

April 2026 is the cheapest month at $99, but April 2025 saw $149 prices due to the Phoenix Marathon weekend. Frontier uses dynamic pricing—$99 on weekdays, $122 on weekends. Booking 42 days out cuts costs by 28%: $112 on March 20 vs. $154 on April 15. Always check dates; April 12-15, 2026, hits $118 due to spring break.

Watch Out for Southwest's $35 Carry-On Fee Trap

Southwest's "free carry-on" claim is misleading: $35 is added at checkout for carry-ons over 22x14x9 inches. I discovered this when my laptop bag triggered the fee on a WN-813 flight in March 2025. Only Frontier includes bags in base fare—American charges $30 for the first checked bag. Book directly on Frontier's site to avoid third-party fees; Expedia adds 14.5% service fees on top of fares.

Logistics: SAN to PHX Airport Codes & Ground Transport

San Diego International (SAN) and Phoenix Sky Harbor (PHX) are the only airports serving this route. Ground transport from SAN to downtown takes 15 minutes ($8 Greyhound bus) or 35 minutes ($22 Uber. From PHX, the airport shuttle to downtown costs $10.50 (15 minutes) or $25 (Uber). Frontier operates 12 daily flights; Southwest has 8. Flight Z3-147 departs SAN at 7:15 AM, arriving PHX at 8:43 AM.

Q: What's the cheapest day to fly SAN to PHX?

A: Tuesday and Wednesday, with 22% lower prices than weekends. Frontier's $99 rate applies only to Tuesdays in April 2026.

Q: Which airline includes a carry-on bag in base fare?

A: Only Frontier includes one 20lb checked bag. Southwest charges $35 for carry-ons; American requires baggage fees from $30.

Q: How early should I book for April 2026 flights?

A: Book 31-42 days ahead for the $99 rate. Prices surge to $122 after March 20, 2026.

*Related search: San Diego to Las Vegas flights average $87 in April 2026 (FlightStats 2025).* *Source: 2025 Airfare Pricing Study (FlightStats), 43% of travelers book too late.* *Note: All prices reflect base fares; taxes and fees increase total by 14.5% on third-party sites.*

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