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$49+ 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 4/23. Fares are subject to change and may not be available on all flights or dates of travel.
SAN — DEN
Mar 31 — Apr 71
Mon 3/31
Mon 4/7
1 adult, Economy
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Cheapflights Tip: The best prices from San Diego to Boulder are usually found in April or January, booked 71 days in advance, depart on a Friday or Saturday and return on a Saturday

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 March 26, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$120
(Trip.com)

One-way from

$49
(Frontier)

Popular in

March

Cheapest in

April

Average price

$250
Provider with most accurate pricing for San Diego-Denver Intl flight deals.
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Provider most trusted by Cheapflights users for San Diego-Denver Intl flights.
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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. 0% potential increase in price ($0 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($7 potential savings vs. average RT price).
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Average for round-trip flights in March 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 March 26, 2025.

This Trip.com deal was found by Cheapflights users on 3/24. 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 4/2312:56 pmSAN - DEN
Nonstop2h 30mFrontier
Sat 5/310:46 amDEN - SAN
Nonstop2h 31mFrontier
Deal found 3/24$120
This Travelocity deal was found by Cheapflights users on 3/24. 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 Travelocity is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2312:56 pmSAN - DEN
Nonstop2h 30mMultiple Airlines
Wed 4/307:00 amDEN - SAN
1 stop8h 34mMultiple Airlines
Deal found 3/24$172
This Southwest deal was found by Cheapflights users on 3/25. 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.
Sat 4/269:30 amSAN - DEN
Nonstop2h 20mSouthwest
Sun 4/278:50 pmDEN - SAN
Nonstop2h 25mSouthwest
Deal found 3/25$187
This United Airlines deal was found by Cheapflights users on 3/25. 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.
Wed 4/232:27 pmSAN - DEN
1 stop6h 46mUnited Airlines
Wed 4/307:58 amDEN - SAN
Nonstop2h 26mUnited Airlines
Deal found 3/25$197
This American Airlines deal was found by Cheapflights users on 3/24. 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.
Wed 4/236:29 amSAN - DEN
1 stop4h 33mAmerican Airlines
Wed 4/306:46 pmDEN - SAN
1 stop3h 51mAmerican Airlines
Deal found 3/24$199
This Hawaiian Airlines deal was found by Cheapflights users on 3/25. 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 Hawaiian Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/241:43 pmSAN - DEN
1 stop9h 16mHawaiian Airlines
Tue 4/297:00 amDEN - SAN
1 stop8h 34mHawaiian Airlines
Deal found 3/25$216
This Delta deal was found by Cheapflights users on 3/25. 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.
Tue 5/276:15 amSAN - DEN
1 stop4h 24mDelta
Wed 6/45:30 amDEN - SAN
1 stop4h 12mDelta
Deal found 3/25$217
This Alaska Airlines deal was found by Cheapflights users on 3/25. 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.
Sun 5/257:00 amSAN - DEN
1 stop10h 09mAlaska Airlines
Tue 6/37:05 pmDEN - SAN
1 stop5h 54mAlaska Airlines
Deal found 3/25$236
This Mytrip deal was found by Cheapflights users on 3/25. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/116:14 pmSAN - DEN
1 stop25h 31mSun Country Air
Mon 4/146:05 pmDEN - SAN
1 stop22h 46mSun Country Air
Deal found 3/25$296

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 March 26, 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

Wed 4/23

12:56 pm-4:26 pm

Nonstop2h 30m

Denver Intl

Sat 5/3

10:46 am-12:17 pm

Nonstop2h 31m

$120

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Wed 4/23

12:56 pm-4:26 pm

Nonstop2h 30m

Denver Intl

Wed 4/30

7:00 am-2:34 pm

1 stop8h 34m

$172

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Sat 4/26

9:30 am-12:50 pm

Nonstop2h 20m

Denver Intl

Sun 4/27

8:50 pm-10:15 pm

Nonstop2h 25m

$187

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Wed 4/23

2:27 pm-10:13 pm

1 stop6h 46m

Denver Intl

Wed 4/30

7:58 am-9:24 am

Nonstop2h 26m

$197

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Wed 4/23

6:29 am-12:02 pm

1 stop4h 33m

Denver Intl

Wed 4/30

6:46 pm-9:37 pm

1 stop3h 51m

$199

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Thu 4/24

1:43 pm-11:59 pm

1 stop9h 16m

Denver Intl

Tue 4/29

7:00 am-2:34 pm

1 stop8h 34m

$216

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Tue 5/27

6:15 am-11:39 am

1 stop4h 24m

Denver Intl

Wed 6/4

5:30 am-8:42 am

1 stop4h 12m

$217

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Sun 5/25

7:00 am-6:09 pm

1 stop10h 09m

Denver Intl

Tue 6/3

7:05 pm-11:59 pm

1 stop5h 54m

$236

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Fri 4/11

6:14 pm-8:45 pm

1 stop25h 31m

Denver Intl

Mon 4/14

6:05 pm-3:51 pm

1 stop22h 46m

$296

San DiegoDenver

SAN - DEN

SANDEN

San Diego

Wed 4/23

12:56 pm-4:26 pm

Nonstop2h 30m

$49

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/24

Showing 1-10 of 17 results
1
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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 March 21, 2025.

Booking 71 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 March 26, 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 March 31, 2024.

Travelers seeking maximum savings on their San Diego to Boulder flight should consider departing on Wednesday evenings when fares are most often at their lowest. Sunday 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 March 26, 2025.

The most flights from SAN to BD9 are scheduled on a Monday (25 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (1 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 March 26, 2025.
Read reviews from past customers who have flown Southwest, Alaska Airlines 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.
Southwest
8.1
Very good
4,274 reviews

Crew

8.6

Boarding

8.2

Overall

8.1

Food

7.1

Comfort

8.1

Entertainment

7.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Southwest
8.1
Very good
4,274 reviews
Southwest
8.1
Very good
4,274 reviews

Crew

8.6

Boarding

8.2

Overall

8.1

Food

7.1

Comfort

8.1

Entertainment

7.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Alaska Airlines
8.0
Very good
9,789 reviews
Southwest
8.1
Very good
4,274 reviews

Crew

8.6

Boarding

8.2

Overall

8.1

Food

7.1

Comfort

8.1

Entertainment

7.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Delta
8.0
Very good
7,891 reviews
Southwest
8.1
Very good
4,274 reviews

Crew

8.6

Boarding

8.2

Overall

8.1

Food

7.1

Comfort

8.1

Entertainment

7.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Hawaiian Airlines
7.9
Good
2,330 reviews
Southwest
8.1
Very good
4,274 reviews

Crew

8.6

Boarding

8.2

Overall

8.1

Food

7.1

Comfort

8.1

Entertainment

7.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
United Airlines
7.4
Good
8,608 reviews
Southwest
8.1
Very good
4,274 reviews

Crew

8.6

Boarding

8.2

Overall

8.1

Food

7.1

Comfort

8.1

Entertainment

7.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

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. 5 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 17 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 208 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 $49 on Frontier. Other airlines that offer cheap prices include American Airlines from $100 and United Airlines from $104 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 Lufthansa (95%), Air Canada (93%) or United Airlines (93%) 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 $1,278 for a flight from San Diego to Boulder. The cheapest flight overall is $48 while the most popular route, (San Diego - Denver Intl) is currently priced at $150.

  • 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.

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Top 5 airlines flying from San Diego to Boulder

Discover the top 5 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 March 26, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$57Average$141FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$163Average$368FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$169Average$337FlexibilityNo cancel feeOn-time63%
DeltaCheapest$196Average$306FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$231Average$343FlexibilityNo cancel feeOn-time71%
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