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Ontario to Chicago flights in December 2026 from $166 ONT → MDW, ORD

Ontario International Airport (ONT) → Chicago Midway International Airport (MDW), O'Hare International Airport (ORD)

For departures in December 2026, the cheapest return found recently is $302 with Frontier Airlines, 30 Dec – 3 Jan 2027, found 2 days ago. The cheapest one-way found recently is $166 with Southwest Airlines, 31 Dec, found 6 days ago.

Return

In December 2026, the cheapest return fare on each of 8 departure dates is usually $264 to $373. Across all 14 departure dates we hold on this route, it is usually $250 to $343. Of the 2 months with enough return fares to compare, December 2026 is usually the most expensive.

Cheapest return found recently

$302

30 Dec – 3 Jan 2027 · Frontier Airlines

Ontario International Airport (ONT) → O'Hare International Airport (ORD)

out 1 stop, back nonstop

found 2 days ago

See prices for these datesCheck today's price

Cheapest we hold, of any age

$218

11 Dec – 15 Dec · Frontier Airlines

Ontario International Airport (ONT) → O'Hare International Airport (ORD)

out 1 stop, back 1 stop

found 4 days ago

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The cheapest dates in December 2026

DatesFromAirlineStopsFound
11 Dec – 15 Dec$218Frontier Airlinesout 1 stop, back 1 stopfound 4 days agoSee prices for these dates
10 Dec – 14 Dec$248Frontier Airlinesout 1 stop, back 1 stopfound 6 days agoSee prices for these dates
15 Dec – 3 Jan 2027$269Frontier Airlinesout 1 stop, back 1 stopfound 3 days agoSee prices for these dates
30 Dec – 3 Jan 2027$302Frontier Airlinesout 1 stop, back nonstopfound 2 days agoSee prices for these dates
28 Dec – 4 Jan 2027$306Southwest Airlinesout nonstop, back nonstopfound 6 days agoSee prices for these dates

Every date we hold

8 departure dates

10 Dec – 14 Dec: $248, found 6 days ago11 Dec – 15 Dec: $218, found 4 days ago15 Dec – 3 Jan 2027: $269, found 3 days ago23 Dec – 27 Dec: $499, found 4 days ago28 Dec – 4 Jan 2027: $306, found 6 days ago29 Dec – 2 Jan 2027: $437, found 4 days ago30 Dec – 3 Jan 2027: $302, found 2 days ago31 Dec – 3 Jan 2027: $351, found 3 days agoDec
See the chart as a table
The cheapest price seen for each departure date — per traveler in Economy.
DatesFromAirlineAirportsStopsFound
10 Dec – 14 Dec$248Frontier AirlinesOntario International Airport (ONT) → O'Hare International Airport (ORD)out 1 stop, back 1 stopfound 6 days agoSee prices for these dates
11 Dec – 15 Dec$218Frontier AirlinesOntario International Airport (ONT) → O'Hare International Airport (ORD)out 1 stop, back 1 stopfound 4 days agoSee prices for these dates
15 Dec – 3 Jan 2027$269Frontier AirlinesOntario International Airport (ONT) → O'Hare International Airport (ORD)out 1 stop, back 1 stopfound 3 days agoSee prices for these dates
23 Dec – 27 Dec$499Southwest AirlinesOntario International Airport (ONT) → Chicago Midway International Airport (MDW)out nonstop, back nonstopfound 4 days agoSee prices for these dates
28 Dec – 4 Jan 2027$306Southwest AirlinesOntario International Airport (ONT) → Chicago Midway International Airport (MDW)out nonstop, back nonstopfound 6 days agoSee prices for these dates
29 Dec – 2 Jan 2027$437American AirlinesOntario International Airport (ONT) → O'Hare International Airport (ORD)out nonstop, back nonstopfound 4 days agoSee prices for these dates
30 Dec – 3 Jan 2027$302Frontier AirlinesOntario International Airport (ONT) → O'Hare International Airport (ORD)out 1 stop, back nonstopfound 2 days agoSee prices for these dates
31 Dec – 3 Jan 2027$351Southwest AirlinesOntario International Airport (ONT) → Chicago Midway International Airport (MDW)out 1 stop, back nonstopfound 3 days agoSee prices for these dates

Which month looks cheapest?

December 2026 is the cheapest month — from $218.

November 2026From $2303 departure dates22 Nov – 3 Dec · found 7 days agoSee prices for these dates
December 2026From $218Cheapest seen8 departure dates11 Dec – 15 Dec · found 4 days agoSee prices for these dates
January 2027From $3201 departure date4 Jan 2027 – 8 Jan 2027 · found 3 days agoSee prices for these dates
February 2027From $2661 departure date12 Feb 2027 – 21 Feb 2027 · found 7 days agoSee prices for these dates
March 2027From $4171 departure date19 Mar 2027 – 22 Mar 2027 · found 4 days agoSee prices for these dates

One-way

We hold one-way fares on only 2 departure dates in December 2026, too few to say what one usually costs.

Cheapest one-way found recently

$166

31 Dec · Southwest Airlines

Ontario International Airport (ONT) → Chicago Midway International Airport (MDW)

1 stop

found 6 days ago

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It is also the cheapest one-way we hold, of any age.

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The cheapest dates in December 2026

DatesFromAirlineStopsFound
31 Dec$166Southwest Airlines1 stopfound 6 days agoOpen this trip
17 Dec$176United Airlines1 stopfound 6 days agoOpen this trip

Every date we hold

2 departure dates

17 Dec: $176, found 6 days ago31 Dec: $166, found 6 days agoDec
See the chart as a table
The cheapest price seen for each departure date — per traveler in Economy.
DatesFromAirlineAirportsStopsFound
17 Dec$176United AirlinesOntario International Airport (ONT) → O'Hare International Airport (ORD)1 stopfound 6 days agoOpen this trip
31 Dec$166Southwest AirlinesOntario International Airport (ONT) → Chicago Midway International Airport (MDW)1 stopfound 6 days agoOpen this trip

Which month looks cheapest?

February 2027 is the cheapest month — from $119.

December 2026From $1662 departure dates31 Dec · found 6 days agoOpen this trip
January 2027From $1292 departure dates11 Jan 2027 · found 2 days agoOpen this trip
February 2027From $119Cheapest seen3 departure dates12 Feb 2027 · found 7 days agoOpen this trip
May 2027From $1731 departure date3 May 2027 · found 3 days agoOpen this trip

Prices are what travelers' searches on Aviasales found in the last 7 days, in US dollars: the price the seller showed on Aviasales; bags may cost extra. Fares change, so check today's price before you book. How our prices work