Anyone planning a holiday trip by air may be paying more this year, with plane ticket prices reaching 10-year highs.

According to travel site Hopper, the average round-trip domestic airfare is now about $400, up roughly 30% from last year. Christmas travel is even more expensive, with average round-trip fares around $450, a 23% increase.

Hopper says travelers have fewer flight options during the holiday season, helping drive prices higher.

The company recommends tracking fares now and booking before Halloween for the best chance at lower prices.