Last week, a coworker of mine was searching for flights to visit family for Christmas, and he said he was speechless when he saw the prices. They were noticeably more expensive than the tickets he bought last year. Hearing that, I decided to look up some numbers myself.

According to the Holiday Travel Index released by travel booking app Hopper, the average round-trip fare for domestic flights during Christmas is $452. This is a 23 percent increase, or about $85 more than last year.

The increase is even greater for Thanksgiving flights. The average round-trip fare is $402, which is a 31 percent rise compared to last year. Hopper described this season as having the highest year-end airfare in the last decade.

So, what caused this? The main reason cited by Hopper is the high and sustained price of jet fuel. For airlines, fuel costs are one of the largest expenses alongside labor costs, so when fuel prices rise, ticket prices follow suit.

Additionally, the supply of low-cost airlines has decreased. In May of this year, Spirit Airlines ceased operations, which removed many cheap seats from the market. When competition decreases, prices tend to hold steady, which is basic economics.

International flights are not exempt either. The same data shows that flights to Mexico and Central America during Christmas have increased by 23 percent, while flights to Europe have risen by 15 percent. Those traveling to Korea are likely feeling similar increases.

Now, let's get to the practical tips. The most useful tip is the day of departure. According to Hopper's analysis, tickets departing on the Monday or Tuesday right before Christmas are the cheapest.

This year, Christmas falls on a Friday. Therefore, departing on Monday, December 21, or Tuesday, December 22, falls within that timeframe. If you can adjust your vacation days by a day or two, it's worth considering.

Conversely, there are definitely days to avoid. The weekend right before Christmas, specifically between December 18 and 20, is when everyone is traveling, resulting in the highest fares. Everyone shares the desire to leave right after work on Friday.

The same principle applies to return dates. The Sunday after Christmas, December 27, is expected to be a peak travel day, making it more expensive than returning earlier in the week. Even delaying your return by just one day can make a significant difference.

For those returning after the New Year, you should also consider the return traffic in early January. Many people return just before the last weekend of the holiday, so fares tend to spike around that time.

So when should you book? To be honest, Hopper recommended that the optimal time to book was before Halloween. That time has already passed.

I personally find this a bit disappointing.

However, that doesn't mean you should just sit back and do nothing. Hopper believes that as the departure date approaches, prices will continue to rise. If you think it's too late now, next week will be even later.

Let me summarize my personal approach. First, set up price alerts on Google Flights or Hopper. You'll receive notifications if prices drop around your desired dates, so you don't have to check constantly.

Second, make sure to enable the date grid or calendar view. This allows you to see how prices change when you shift your dates by a day or two, letting you directly observe the benefits of departing on a Monday.

Third, compare two or three nearby airports. It's often the case that airports within a one or two-hour drive are cheaper. However, you need to factor in parking fees, gas costs, and driving fatigue to determine if it's truly a savings.

Fourth, don't just look at the base fare; also consider baggage fees. During the holidays, luggage tends to increase due to gifts, so savings from basic economy can often be offset by checked bag fees.

Fifth, choose fares that allow free cancellations or changes if possible. This way, if a cheaper fare appears later, you have the option to switch.

You should also keep accommodations in mind. According to reports citing Hopper data, the average hotel rate for domestic stays during Christmas is $197 per night, which is an 18 percent increase. It's pointless to save on flights if you end up spending it all on hotels.

One thing to clarify is that these numbers are national averages based on one company's data. Actual prices can vary significantly depending on the route and departure airport.

So, if you see a fare that's cheaper than average, grab it; if it's more expensive, consider shifting your travel days. Use these figures as a guideline rather than a strict rule. Comparing directly on your route is the most accurate approach.

On the other hand, I also understand this perspective. From the airlines' standpoint, rising fuel costs and reduced competition may justify higher prices. From the consumer's perspective, it's frustrating that the cost of traveling to see family just once a year has become so high.

I can empathize with both sides. However, ultimately, what we can change is not the airline policies but our departure dates and booking timing.

Consider a family of four traveling. Even looking at averages, that's an additional $85 per person compared to last year, totaling over $300 for four people. If changing just one day can reduce that cost, it's worth trying.

If I were to book tickets this year, I would aim for a departure on Monday the 21st and look to return on the 28th or 29th, avoiding the busy Sunday. And I would set up alerts right away.

In summary, it's simple. Choose Monday or Tuesday instead of the weekend, avoid returning on the busy Sunday, and don't delay—start comparing now. Following these three tips can significantly improve your holiday budget.

I hope everyone has a safe and warm holiday season with family, while spending a little less.