Fares to Australia keep dropping and have now dipped into the $400s roundtrip from multiple cities across the U.S. and in the $500s from nearly every airport in the nation where United flies to both Sydney (SYD) and Melbourne (MEL). Flights to other Australian cities are lower than usual as well.

These lower fares can be found when searching on certain third-party websites such as Priceline. Fares will be slightly higher if you book directly on the airline's website.

Travel rules vary slightly by route. The lower fares in the $400s from certain hub cities are available for daily travel on scattered dates departing the U.S. through October.

For other cities, travel is valid on Mondays, Tuesdays, Wednesdays, and Thursdays, with departures from the U.S. through early July, in August/September, and November. These routes also require a 10-night minimum stay and a 14-day advanced purchase.

This sale is unadvertised and prices may jump at any time. Book your dream trip to Oz now.

A sample of fares include:

Philadelphia to Sydney $459 roundtrip

Dallas to Sydney $459 roundtrip

Phoenix to Sydney $459 roundtrip

Los Angeles to Melbourne $470 roundtrip, nonstop

Houston to Sydney $480 roundtrip, nonstop

Dallas to Melbourne $481 roundtrip

Los Angeles to Sydney $482 roundtrip, nonstop

Washington D.C. to Melbourne $487 roundtrip

Newark to Sydney $495 roundtrip

Washington D.C. to Sydney $495 roundtrip

New York to Sydney $495 roundtrip

Chicago to Sydney $495 roundtrip

Denver to Sydney $495 roundtrip

Orange County to Sydney $537 roundtrip

Las Vegas to Sydney $539 roundtrip

San Diego to Sydney $539 roundtrip

Sacramento to Sydney $539 roundtrip

Seattle to Sydney $553 roundtrip

Grand Rapids to Sydney $572 roundtrip

Indianapolis to Sydney $572 roundtrip

St. Louis to Sydney $572 roundtrip

Duluth to Sydney $577 roundtrip

Pittsburgh to Sydney $585 roundtrip

Tampa to Sydney $585 roundtrip

Boston to Sydney $588 roundtrip

Columbus to Sydney $588 roundtrip

Ft. Lauderdale to Sydney $588 roundtrip

Fayetteville to Sydney $588 roundtrip

New Orleans to Sydney $588 roundtrip

This is just a small sample of fares. As this is nationwide, check flights from your city (large or small) even if it isn't listed, and you'll likely find a great price on a flight to Australia using the date range and rules listed above.

Unfortunately, some of the major Delta hubs are not included in this sale, but you may find a nearby airport with a low fare.

As an example, when searching on Priceline, I found seats departing Philadelphia PHL on Monday, March 4, returning from Sydney SYD on Tuesday, March 19, for $459 roundtrip.