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$79+ Cheap flights from San Diego (SAN) to Illinois

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 9/18. Fares are subject to change and may not be available on all flights or dates of travel.
SAN — ORD
Aug 23 — Aug 301
Sat 8/23
Sat 8/30
1 adult, Economy
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Cheap flight deals from San Diego to Illinois

Keep the following information in mind while searching for San Diego to Illinois flight deals. Data was last updated August 18, 2025.

Round-trip from

$145
(Priceline)

One-way from

$79
(Priceline)

Popular in

December

Cheapest in

August

Average price

$259

Good round-trip deal

$205 or less

Good one-way deal

$144 or less
From San Diego to Illinois
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One-way flight from San Diego to Illinois
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Highest demand for flights based on searches. 14% potential increase in price ($62 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($10 potential savings vs. average RT price).
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Average for round-trip flights in August 2025
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Price to beat on a round-trip flight from San Diego to Illinois.
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Price to beat on a one-way flight from San Diego to Illinois.
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Find flight deals from San Diego to Illinois

Cheapest flights from San Diego to Illinois
Explore the most affordable flight options available from San Diego to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 18, 2025.

This Priceline deal was found by Cheapflights users on 8/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/49:03 pmSAN - STL
1 stop10h 03mFrontier
Mon 9/87:55 pmSTL - SAN
1 stop5h 58mFrontier
Deal found 8/17$145
This Priceline deal was found by Cheapflights users on 8/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/119:03 pmSAN - STL
1 stop10h 03mFrontier
Sun 9/1410:39 amSTL - SAN
1 stop8h 03mFrontier
Deal found 8/17$151
This CheapOair deal was found by Cheapflights users on 8/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/236:41 amSAN - MDW
1 stop15h 55mFrontier
Mon 10/276:24 pmMDW - SAN
1 stop7h 26mFrontier
Deal found 8/16$152
This Priceline deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/36:25 amSAN - STL
1 stop5h 28mFrontier
Tue 10/77:52 pmSTL - SAN
1 stop5h 58mFrontier
Deal found 8/14$152
This Kiwi.com deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/192:31 pmSAN - ORD
1 stop6h 09mFrontier
Sun 9/216:00 amORD - SAN
1 stop7h 09mFrontier
Deal found 8/15$153
This Gotogate deal was found by Cheapflights users on 8/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/412:04 pmSAN - MDW
1 stop25h 49mFrontier
Fri 9/124:48 pmMDW - SAN
1 stop9h 05mFrontier
Deal found 8/17$153
This United Airlines deal was found by Cheapflights users on 8/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/132:11 pmSAN - ORD
Nonstop4h 14mUnited Airlines
Sat 9/204:00 pmORD - SAN
Nonstop4h 20mUnited Airlines
Deal found 8/16$154
This Trip.com deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/1512:20 pmSAN - ORD
Nonstop4h 39mMultiple Airlines
Sun 10/197:15 amORD - SAN
Nonstop4h 22mMultiple Airlines
Deal found 8/14$155
This Kiwi.com deal was found by Cheapflights users on 8/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/1412:20 pmSAN - ORD
Nonstop4h 39mMultiple Airlines
Thu 11/136:00 amORD - SAN
1 stop19h 50mMultiple Airlines
Deal found 8/17$156
This Frontier deal was found by Cheapflights users on 8/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/253:40 pmSAN - ORD
Nonstop4h 23mFrontier
Mon 10/66:00 amORD - SAN
1 stop7h 09mFrontier
Deal found 8/17$157
This CheapOair deal was found by Cheapflights users on 8/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/66:25 amSAN - MDW
1 stop12h 18mFrontier
Mon 11/1012:30 pmMDW - SAN
1 stop13h 20mFrontier
Deal found 8/17$157
This Priceline deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/307:01 pmSAN - ORD
1 stop7h 49mMultiple Airlines
Sun 9/77:55 amORD - SAN
Nonstop4h 35mMultiple Airlines
Deal found 8/15$158

Cheapflights Fare Finder

 
Customize your flight search to find flights from San Diego to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated August 18, 2025.
Use the filters below to find and compare flights from San Diego to Illinois that are best for you.

Fly from

San Diego

Fly to

Illinois

Route

Depart

Return

Price

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Fri 10/17

9:03 pm-9:07 am

1 stop10h 04m

Lambert-St Louis

Fri 10/24

7:52 pm-11:50 pm

1 stop5h 58m

$145

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Thu 9/4

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Mon 9/8

7:55 pm-11:53 pm

1 stop5h 58m

$145

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Fri 10/10

9:03 pm-9:07 am

1 stop10h 04m

Lambert-St Louis

Mon 10/13

7:52 pm-11:50 pm

1 stop5h 58m

$145

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Sun 9/21

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Sun 9/28

7:55 pm-11:53 pm

1 stop5h 58m

$145

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Thu 9/18

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Mon 9/22

7:55 pm-11:53 pm

1 stop5h 58m

$145

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Thu 9/11

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Sun 9/21

10:39 am-4:42 pm

1 stop8h 03m

$151

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Thu 9/11

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Sun 9/14

10:39 am-4:42 pm

1 stop8h 03m

$151

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Sun 9/14

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Sun 9/21

10:39 am-4:42 pm

1 stop8h 03m

$151

San DiegoSt. Louis

SAN - STL

SANSTL

San Diego

Thu 9/4

9:03 pm-9:06 am

1 stop10h 03m

Lambert-St Louis

Sun 9/7

10:39 am-4:42 pm

1 stop8h 03m

$151

San DiegoChicago

SAN - MDW

SANMDW

San Diego

Thu 10/23

6:41 am-12:36 am

1 stop15h 55m

Chicago Midway

Mon 10/27

6:24 pm-11:50 pm

1 stop7h 26m

$152

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/15

Showing 1-10 of 60 results
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Best time to book a flight from San Diego to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from San Diego with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from San Diego to Illinois

What is the cheapest month to book a flight from San Diego to Illinois?

Currently, August is the cheapest month in which you can book a flight from San Diego to Illinois (average of $245). Flying from San Diego to Illinois in March is currently the most expensive (average of $321). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from SAN to IL?

Find hourly flight availability from San Diego to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated August 18, 2025.

When flying from San Diego to Illinois, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

Weekly flight availability from San Diego to Illinois

Explore weekly flight availability from San Diego to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated August 18, 2025.

The most flights from SAN to USIL are scheduled on a Sunday (51 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (20 on average).

Reviews of airlines servicing Illinois

Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated August 18, 2025.
Read reviews from past customers who have flown Southwest, United Airlines, and American Airlines from San Diego to Illinois. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,246 reviews

Entertainment

7.5

Boarding

8.1

Overall

8.0

Food

7.0

Crew

8.6

Comfort

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Southwest
8.0
Very good
4,246 reviews
Southwest
8.0
Very good
4,246 reviews

Entertainment

7.5

Boarding

8.1

Overall

8.0

Food

7.0

Crew

8.6

Comfort

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
United Airlines
7.4
Good
8,925 reviews
Southwest
8.0
Very good
4,246 reviews

Entertainment

7.5

Boarding

8.1

Overall

8.0

Food

7.0

Crew

8.6

Comfort

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,246 reviews

Entertainment

7.5

Boarding

8.1

Overall

8.0

Food

7.0

Crew

8.6

Comfort

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Spirit Airlines
6.3
Okay
8,038 reviews
Southwest
8.0
Very good
4,246 reviews

Entertainment

7.5

Boarding

8.1

Overall

8.0

Food

7.0

Crew

8.6

Comfort

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Frontier
5.8
Fair
3,212 reviews
Southwest
8.0
Very good
4,246 reviews

Entertainment

7.5

Boarding

8.1

Overall

8.0

Food

7.0

Crew

8.6

Comfort

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.

Related info for your journey

Find useful and relevant information for your journey from San Diego to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from San Diego to Illinois?

    Located just 2.6 mi from the city center, San Diego (SAN) is the airport most travelers will use when flying to Illinois from San Diego.

  • What are the cheapest airlines to fly from San Diego to Illinois one-way?

    One-way options have recently been found by users for as low as $79 on Frontier. Other airlines that offer cheap prices include Spirit Airlines from $80 and American Airlines from $126 one-way.

  • What are the most popular routes from San Diego to Illinois?

    While some choose either San Diego - Chicago Midway or San Diego - Lambert-St Louis, San Diego - Chicago O'Hare Intl is the most popular route from San Diego to Illinois.

  • What are the most reliable airlines from San Diego to Illinois?

    The top 3 most reliable airlines when flying from San Diego to Illinois are Royal Jordanian (87%), Austrian Airlines (85%) and Cathay Pacific (84%).

  • What are the cheapest flights from San Diego to Illinois?

    While on average a flight from San Diego to Illinois is generally $880, our data shows the cheapest flight currently is $86. When looking at the most popular route, (San Diego - Chicago O'Hare Intl), you can expect to pay $116 for that flight.

  • Can I find deals for flights from San Diego to Illinois that include hotel bookings?

    Yes. In addition to deals on San Diego to Illinois flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from San Diego to Illinois?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from San Diego to Illinois.

  • Can I find deals for business class flights from San Diego to Illinois?

    Yes. Cheapflights offers flight deals from San Diego to Illinois by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from San Diego to Illinois?

    Currently, August is the cheapest month in which you can book a flight from San Diego to Illinois (average of $245). Flying from San Diego to Illinois in March is currently the most expensive (average of $321). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

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Alternative routes for San Diego to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 7 airlines flying from San Diego to Illinois

Discover the top 7 airlines that operate flights from San Diego to Illinois. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated August 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$98Average$180FlexibilityNo cancel feeOn-time65%
FrontierCheapest$116Average$207FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$175Average$467FlexibilityNo cancel feeOn-time71%
Alaska AirlinesCheapest$184Average$537FlexibilityNo cancel feeOn-time75%
United AirlinesCheapest$225Average$512FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$236Average$431FlexibilityNo cancel feeOn-time63%
DeltaCheapest$267Average$387FlexibilityNo cancel feeOn-timeN/A

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