$249 Cheap Flights from Boise (BOI) to Sidney (SDY)

View $249 flight on Mon, Jan 12, 2026Opens in a new window

Popular airlines from Boise Airport (BOI) to Sidney, MT (SDY-Sidney-Richland Municipal)

Cheap Flights from Boise to Sidney (BOI-SDY)

Prices were available within the past 7 days and start at $249 for one-way flights and $426 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Delta
Wed, Jan 14 - Tue, Jan 20
BOI
Boise
SDY
Sidney
$426 Roundtrip, found 3 days ago
$426
Roundtrip
found 3 days ago
Select Delta flight, departing Wed, Jan 14 from Boise to Sidney, returning Tue, Jan 20, priced at $426 found 3 days ago
Alaska Airlines
Sat, Jan 17 - Sat, Jan 24
BOI
Boise
SDY
Sidney
$445 Roundtrip, found 6 days ago
$445
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Jan 17 from Boise to Sidney, returning Sat, Jan 24, priced at $445 found 6 days ago
Delta
Wed, Jan 14 - Sun, Jan 25
BOI
Boise
SDY
Sidney
$447 Roundtrip, found 3 days ago
$447
Roundtrip
found 3 days ago
Select Delta flight, departing Wed, Jan 14 from Boise to Sidney, returning Sun, Jan 25, priced at $447 found 3 days ago
Alaska Airlines
Sat, Jan 17 - Sat, Jan 24
BOI
Boise
SDY
Sidney
$448 Roundtrip, found 6 days ago
$448
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Jan 17 from Boise to Sidney, returning Sat, Jan 24, priced at $448 found 6 days ago
Alaska Airlines
Sat, Jan 17 - Sat, Jan 24
BOI
Boise
SDY
Sidney
$451 Roundtrip, found 6 days ago
$451
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Jan 17 from Boise to Sidney, returning Sat, Jan 24, priced at $451 found 6 days ago
Alaska Airlines
Sat, Jan 17 - Fri, Jan 23
BOI
Boise
SDY
Sidney
$458 Roundtrip, found 3 days ago
$458
Roundtrip
found 3 days ago
Select Alaska Airlines flight, departing Sat, Jan 17 from Boise to Sidney, returning Fri, Jan 23, priced at $458 found 3 days ago
Alaska Airlines
Sat, Jan 17 - Fri, Jan 23
BOI
Boise
SDY
Sidney
$461 Roundtrip, found 3 days ago
$461
Roundtrip
found 3 days ago
Select Alaska Airlines flight, departing Sat, Jan 17 from Boise to Sidney, returning Fri, Jan 23, priced at $461 found 3 days ago
Alaska Airlines
Sat, Jan 17 - Sat, Jan 24
BOI
Boise
SDY
Sidney
$462 Roundtrip, found 6 days ago
$462
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Jan 17 from Boise to Sidney, returning Sat, Jan 24, priced at $462 found 6 days ago
Hawaiian Airlines
Sun, Jan 18 - Sun, Jan 25
BOI
Boise
SDY
Sidney
$471 Roundtrip, found 3 days ago
$471
Roundtrip
found 3 days ago
Select Hawaiian Airlines flight, departing Sun, Jan 18 from Boise to Sidney, returning Sun, Jan 25, priced at $471 found 3 days ago
United
Sat, Jan 17 - Fri, Jan 23
BOI
Boise
SDY
Sidney
$477 Roundtrip, found 3 days ago
$477
Roundtrip
found 3 days ago
Select United flight, departing Sat, Jan 17 from Boise to Sidney, returning Fri, Jan 23, priced at $477 found 3 days ago

Black Friday Sale

Limited-time deals: Save up to 50% on select hotels.
Book now
Flights from Boise (BOI) to Sidney (SDY)
Origin airport
Boise
Destination airport
Sidney-Richland Municipal
Roundtrip price
$425
Distance
646 mi

Boise to Sidney Flights

The cheapest times to fly from Boise to Sidney

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Boise to Sidney are during the month of January. You can find some of the cheapest flights from Boise to Sidney with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Boise to Sidney

Sunday is one of the best days to book for cheap flights from Boise to Sidney: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Boise to Sidney

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Boise to Sidney in 2025. You can also book with separate airlines for your outbound and return journeys, from $249 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Boise to Sidney flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Boise to Sidney airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY) cost?
Lock in a cheap one-way flight from $249 or cheap return flight from $426 from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight offers on this route.
What is the cheapest month to fly from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY)?
The cheapest month to fly from BOI to SDY is January, when demand is low. Off-peak months are generally when airlines offer better prices between these airports.
What is the cheapest airline that flies from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY)?
Use the filter tool on Expedia to compare airlines and find the cheapest carrier that'll take you from BOI to SDY. Then, sort your results by "Price (lowest to highest)" to snap up a great deal.
How many flights per day from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY)?
There aren't any daily nonstop flights from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY). But you can choose flights with layovers. Filter your search on Expedia to include one or more stops, and you'll be soaring above the clouds in no time at all.
What day of the week has the most flights from BOI to SDY?
You'll typically find Tuesday the quietest day for flights, while Fridays are often the busiest.* However this can vary from season to season and during peak travel times or public holidays.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY)?
Choose a flight from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY) that leaves before 3 PM to reduce the risk of cancellations. Departures after this hour are on average 22% more likely to be canceled.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
Is it cheaper to buy a plane ticket from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY) last-minute?
Last-minute bookings from BOI to SDY are generally more expensive. To lock in the lowest prices, start looking for flights well ahead of time. That being said, if you're flexible with your travel plans, you may score a cheap fare just before your departure.
Is it cheaper to book a BOI to SDY flight and hotel package?
Compared with arranging flights and hotels separately, booking a BOI to SDY flight and hotel package with Expedia could lead to significant savings. What's more, having it all in one place takes the hassle out of travel planning. Just secure your flights and choose from our extensive range of hotels, then tailor your trip with extras like tours, activities and car rentals.
Can I cancel or change the date of my flight from Boise Airport (BOI) to Sidney-Richland Municipal Airport (SDY)?
If you booked your BOI to SDY flight within the last 24 hours, you may be able to modify or cancel it at no cost. Depending on the airline and the type of ticket you have, additional charges may apply for changes beyond that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, go to our Customer Service portal if you'd like more information.

Explore a world of travel with Expedia

*Available to One Key members.