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$78+ Cheap flights from San Diego (SAN) to Boulder, CO

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 10/14. Fares are subject to change and may not be available on all flights or dates of travel.
SAN — DEN
jun. 17 — jun. 241
mar. 6/17
mar. 6/24
1 adult, Economy
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Cheapflights Tip: The best prices from San Diego to Boulder are usually found in January or February, booked 44 days in advance, depart on a Saturday or Thursday and return on a Tuesday

Cheap flight deals from San Diego to Boulder

Keep the following information in mind while searching for San Diego to Boulder flight deals. Data was last updated junio 12, 2025.

Round-trip from

$127
(Cheapflightsfares)

One-way from

$79
(United Airlines)

Popular in

March

Cheapest in

January

Average price

$235
From San Diego to Boulder
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One-way flight from San Diego to Boulder
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Highest demand for flights based on searches. 3% potential increase in price ($8 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($6 potential savings vs. average RT price).
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Average for round-trip flights in June 2025
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Find flight deals from San Diego to Boulder

Cheapest flights from San Diego to Boulder
Explore the most affordable flight options available from San Diego to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on junio 12, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 6/10. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 7/96:25 amSAN - DEN
Nonstop2h 37mFrontier
mié. 7/169:44 amDEN - SAN
Nonstop2h 26mFrontier
Deal found 6/10$127
This American Airlines deal was found by Cheapflights users on 6/12. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mar. 9/238:15 amSAN - DEN
1 stop5h 12mAmerican Airlines
sáb. 9/273:07 pmDEN - SAN
1 stop5h 17mAmerican Airlines
Deal found 6/12$177
This Delta deal was found by Cheapflights users on 6/11. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sáb. 7/269:59 amSAN - DEN
1 stop7h 18mDelta
sáb. 8/25:30 amDEN - SAN
1 stop4h 08mDelta
Deal found 6/11$217
This Southwest deal was found by Cheapflights users on 6/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sáb. 12/136:30 amSAN - DEN
Nonstop2h 30mSouthwest
lun. 12/151:30 pmDEN - SAN
1 stop4h 25mSouthwest
Deal found 6/10$266
This Alaska Airlines deal was found by Cheapflights users on 6/10. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mar. 9/238:05 amSAN - DEN
2 stops11h 22mAlaska Airlines
mié. 9/249:23 pmDEN - SAN
1 stop13h 51mAlaska Airlines
Deal found 6/10$282

Cheapflights Fare Finder

Customize your flight search to find flights from San Diego to Boulder 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 junio 12, 2025.
Use the filters below to find and compare flights from San Diego to Boulder that are best for you.

Fly from

San Diego

Fly to

Boulder

Route

Depart

Return

Price

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mié. 7/9

6:25 am-10:02 am

Nonstop2h 37m

Denver Intl

mié. 7/16

9:44 am-11:10 am

Nonstop2h 26m

$127

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 9/23

8:15 am-2:27 pm

1 stop5h 12m

Denver Intl

sáb. 9/27

3:07 pm-7:24 pm

1 stop5h 17m

$177

San DiegoDenver

SAN - DEN

SANDEN

San Diego

sáb. 7/26

9:45 am-3:00 pm

1 stop4h 15m

Denver Intl

mar. 8/12

7:21 pm-10:54 pm

1 stop4h 33m

$217

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 7/29

7:35 pm-11:00 pm

Nonstop2h 25m

Denver Intl

jue. 7/31

5:35 am-9:15 am

1 stop4h 40m

$225

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 9/23

8:05 am-8:27 pm

2 stops11h 22m

Denver Intl

mié. 9/24

9:23 pm-10:14 am

1 stop13h 51m

$282

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 10/14

8:19 pm-11:47 pm

Nonstop2h 28m

$78

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 9/16

12:52 pm-4:20 pm

Nonstop2h 28m

$79

San DiegoDenver

SAN - DEN

SANDEN

San Diego

lun. 8/11

1:03 pm-4:00 am

1 stop13h 57m

$82

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 7/8

6:15 am-7:19 pm

1 stop12h 04m

$83

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 10/14

10:24 am-6:08 pm

1 stop6h 44m

$88

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/12

Showing 1-10 of 13 results
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Best time to book a flight from San Diego to Boulder

Have a flexible travel schedule? Discover the best time to fly to Boulder 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 Boulder

How far ahead should I book a flight from San Diego to Boulder?

Use this chart to determine the optimal time to book a round-trip flight from San Diego to Boulder. Price data was last updated on June 9, 2025.

Booking 44 days in advance of your planned departure date is, on average, the best time to get cheap flights from San Diego to Boulder. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

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

Currently, October is the cheapest month in which you can book a flight from San Diego to Boulder (average of $197). Flying from San Diego to Boulder in March is currently the most expensive (average of $278). 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 BD9?

Find hourly flight availability from San Diego to Boulder. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated junio 12, 2025.

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

What is the cheapest day to fly from San Diego to Boulder?

Use this chart to determine the cheapest time to fly round-trip from San Diego to Boulder. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their San Diego to Boulder flight should consider departing on Saturday evenings when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from San Diego to Boulder

Explore weekly flight availability from San Diego to Boulder. 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 junio 12, 2025.

The most flights from SAN to BD9 are scheduled on a Thursday (26 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (10 on average).

Rainfall in Boulder by month

Plan your trip to Boulder by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Boulder ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Boulder when rainfall is around 0.5 in.

Temperature in Boulder by month

Plan your trip to Boulder by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Boulder, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

Reviews of airlines servicing Boulder

Get insights into the airlines that provide service to Boulder. 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 Boulder. Reviews last updated junio 12, 2025.
Read reviews from past customers who have flown Alaska Airlines, Southwest and Delta from San Diego to Boulder. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Comfort

7.8

Entertainment

7.1

Overall

8.0

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Comfort

7.8

Entertainment

7.1

Overall

8.0

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Southwest
8.0
Very good
4,287 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Comfort

7.8

Entertainment

7.1

Overall

8.0

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Delta
8.0
Very good
7,946 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Comfort

7.8

Entertainment

7.1

Overall

8.0

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
United Airlines
7.4
Good
8,790 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Comfort

7.8

Entertainment

7.1

Overall

8.0

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Comfort

7.8

Entertainment

7.1

Overall

8.0

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.

Related info for your journey

Find useful and relevant information for your journey from San Diego to Boulder. 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 Boulder?

    San Diego (SAN), located 2.6 mi from the city center, is the airport you fly out of when you book flights from San Diego to Boulder. 6 airlines have flights from San Diego to Boulder on a regular basis. Booking flights from San Diego to Boulder should not be difficult; the airport handles an average of 20 outbound flights to Boulder per day.

  • How popular is this San Diego to Boulder flight route?

    Flights from San Diego to Boulder have been viewed 165 times in the past calendar month.

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

    One-way options have recently been found by users for as low as $79 on United Airlines. Other airlines that offer cheap prices include Frontier from $82 and Southwest from $88 one-way.

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

    No one likes to see their flight delayed. When booking a flight from San Diego to Boulder consider choosing Sun Country Air (100%), United Airlines (78%) or Air Canada (77%) as they are the most reliable in getting you off to your destination on time.

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

    On average you can expect to pay $1,087 for a flight from San Diego to Boulder. The cheapest flight overall is $75 while the most popular route, (San Diego - Denver Intl) is currently priced at $121.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from San Diego to Boulder 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 Boulder?

    Currently, October is the cheapest month in which you can book a flight from San Diego to Boulder (average of $197). Flying from San Diego to Boulder in March is currently the most expensive (average of $278). 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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Top 6 airlines flying from San Diego to Boulder

Discover the top 6 airlines that operate flights from San Diego to Boulder. 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 junio 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$58Average$156FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$167Average$418FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$176Average$331FlexibilityNo cancel feeOn-time63%
Alaska AirlinesCheapest$177Average$245FlexibilityNo cancel feeOn-time75%
DeltaCheapest$196Average$306FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$197Average$335FlexibilityNo cancel feeOn-time71%

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