What are the cheapest airlines to fly from Phoenix Sky Harbor Intl Airport to Boulder one-way?

The cheapest airlines for a one-way flight from Phoenix Sky Harbor Intl Airport to Boulder are Frontier ($33), United Airlines ($80), and American Airlines ($82).

Weekly flight availability from Phoenix Sky Harbor Intl Airport to Boulder

The most flights from PHX to BD9 are scheduled on a Monday (44 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (14 on average).

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.

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).

What are the cheapest flights from Phoenix Sky Harbor Intl Airport to Boulder?

Looking at all options, your cheapest flight can be booked for $88. While the most popular route (Phoenix Sky Harbor Intl - Denver Intl) can be booked for $123 on average, our data indicates $834 when flying from Phoenix Sky Harbor Intl Airport to Boulder.

What are the most reliable airlines from Phoenix Sky Harbor Intl Airport to Boulder?

Consider Air Canada (83%), United Airlines (82%) or Lufthansa (81%) when booking your flight. These represent the most reliable airlines when flying from Phoenix Sky Harbor Intl Airport to Boulder.

What are the most popular airlines that fly from Phoenix Sky Harbor Intl Airport to Boulder?

Frontier, Southwest and United Airlines are the most popular airlines when flying from Phoenix Sky Harbor Intl Airport to Boulder.

Can I find deals for flights from Sky Harbor Intl to Boulder that include hotel bookings?

Yes. In addition to deals on Sky Harbor Intl to Boulder flights, Cheapflights offers vacation packages that include both flights and hotel.

How can I find direct flights from Sky Harbor Intl to Boulder?

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

Can I find deals for business class flights from Sky Harbor Intl to Boulder?

Yes. Cheapflights offers flight deals from Sky Harbor Intl 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.

Find Cheap Flights from Phoenix Sky Harbor Intl Airport to Boulder

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Cheapflights Tip: The best prices from Phoenix Sky Harbor Intl to Boulder are usually found in February or April, booked 69 days in advance, depart on a Saturday or Friday and return on a Saturday

Find flight deals from Sky Harbor Intl to Boulder

Popular in	September
Cheapest in	February
Average price	$209

Highest demand for flights based on searches. 8% potential increase in price ($19 potential increase over avg. RT price).

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Cheapest flight prices on average. 2% potential price decrease ($5 potential savings vs. average RT price).

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Average for round-trip flights in November 2026

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Everything you need to know about your flight from Phoenix Sky Harbor Intl Airport to Boulder

Prices

Airlines

What is the cheapest time of day to fly from PHX to BD9?

A simple way to save on the total cost of your ticket is to fly from Phoenix Sky Harbor Intl Airport to Boulder in the evening. If you’re flexible enough to do this you can expect to save up to 28% on your trip compared to booking a flight at noon.

What is the cheapest day to fly from Phoenix Sky Harbor Intl Airport to Boulder?

Travelers seeking maximum savings on their Phoenix Sky Harbor Intl Airport to Boulder flight should consider departing on Thursday evenings when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Reviews of airlines servicing Boulder

Read through reviews of airlines operating flights from Phoenix Sky Harbor Intl Airport to Boulder, such as Southwest,United Airlines, andAmerican Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

Southwest

8.0

Very good

4,215 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Southwest

8.0

Very good

4,215 reviews

Southwest

8.0

Very good

4,215 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

United Airlines

7.3

Good

10,458 reviews

Southwest

8.0

Very good

4,215 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

American Airlines

7.0

Good

12,233 reviews

Southwest

8.0

Very good

4,215 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Frontier

5.5

Fair

2,512 reviews

Southwest

8.0

Very good

4,215 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Related info for your journey

What are the cheapest airlines to fly from Phoenix Sky Harbor Intl Airport to Boulder one-way?
The cheapest airlines for a one-way flight from Phoenix Sky Harbor Intl Airport to Boulder are Frontier ($33), United Airlines ($80), and American Airlines ($82).
What are the most reliable airlines from Phoenix Sky Harbor Intl Airport to Boulder?
Consider Air Canada (83%), United Airlines (82%) or Lufthansa (81%) when booking your flight. These represent the most reliable airlines when flying from Phoenix Sky Harbor Intl Airport to Boulder.
What are the cheapest flights from Phoenix Sky Harbor Intl Airport to Boulder?
Looking at all options, your cheapest flight can be booked for $88. While the most popular route (Phoenix Sky Harbor Intl - Denver Intl) can be booked for $123 on average, our data indicates $834 when flying from Phoenix Sky Harbor Intl Airport to Boulder.
Can I find deals for flights from Sky Harbor Intl to Boulder that include hotel bookings?
Yes. In addition to deals on Sky Harbor Intl to Boulder flights, Cheapflights offers vacation packages that include both flights and hotel.
How can I find direct flights from Sky Harbor Intl to Boulder?
After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Sky Harbor Intl to Boulder.
Can I find deals for business class flights from Sky Harbor Intl to Boulder?
Yes. Cheapflights offers flight deals from Sky Harbor Intl 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.

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Top 4 airlines flying from Sky Harbor Intl to Boulder

Airline	Cheapest	Average	Flexibility	On-time
Frontier	Cheapest$62	Average$166	FlexibilityNo cancel fee	On-time62%
American Airlines	Cheapest$154	Average$283	FlexibilityNo cancel fee	On-time71%
United Airlines	Cheapest$160	Average$334	FlexibilityNo cancel fee	On-time69%
Southwest	Cheapest$177	Average$340	FlexibilityNo cancel fee	On-time63%

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Cheap flights from Sky Harbor Intl (PHX) to Boulder, CO

Find cheap flights from Sky Harbor Intl to Boulder with Cheapflights

1. Tell us where you want to go

2. Select your favorite providers

3. Compare prices and book

Find flight deals from Sky Harbor Intl to Boulder

Popular in

Cheapest in

Average price

Cheapflights Insights

What is the cheapest time of day to fly from PHX to BD9?

A simple way to save on the total cost of your ticket is to fly from Phoenix Sky Harbor Intl Airport to Boulder in the evening. If you’re flexible enough to do this you can expect to save up to 28% on your trip compared to booking a flight at noon.

What is the cheapest day to fly from Phoenix Sky Harbor Intl Airport to Boulder?

Travelers seeking maximum savings on their Phoenix Sky Harbor Intl Airport to Boulder flight should consider departing on Thursday evenings when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Phoenix Sky Harbor Intl Airport to Boulder

The most flights from PHX to BD9 are scheduled on a Monday (44 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (14 on average).

Reviews of airlines servicing Boulder

Read through reviews of airlines operating flights from Phoenix Sky Harbor Intl Airport to Boulder, such as Southwest,United Airlines, andAmerican Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

Related info for your journey

What are the cheapest airlines to fly from Phoenix Sky Harbor Intl Airport to Boulder one-way?

What are the most reliable airlines from Phoenix Sky Harbor Intl Airport to Boulder?

What are the cheapest flights from Phoenix Sky Harbor Intl Airport to Boulder?

Can I find deals for flights from Sky Harbor Intl to Boulder that include hotel bookings?

How can I find direct flights from Sky Harbor Intl to Boulder?

Can I find deals for business class flights from Sky Harbor Intl to Boulder?

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Sky Harbor Intl to Boulder

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Complete your trip

Complete your trip to Boulder by adding a car rental and/or hotel reservation to your travel itinerary.

Search flights from Sky Harbor Intl to Boulder by cabin class

Find flights from Sky Harbor Intl to Boulder, based on your preferred cabin class, be it economy, premium economy, business, or first class.

Sky Harbor Intl and Boulder flights

Browse other Sky Harbor Intl and Boulder flight options. Last updated on November 3, 2026.

Other flights from Sky Harbor Intl

Browse through other flights departing from Sky Harbor Intl. Flights are based on user searches made on Cheapflights and were last updated on November 3, 2026.

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Sky Harbor Intl to Boulder flights

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Top 4 airlines flying from Sky Harbor Intl to Boulder

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