Australia has been on sale pretty often lately. This week we're seeing some bigger price drops from hub cities across the nation, including nonstop flights. Fares start at $578 roundtrip for year-round travel.

This is an all-out fare war with cheap flights on all airlines from competing hub cities. The lowest fares on Qantas or Virgin Australia are found on some common third-party sites like Vayama and JustFly. United fares may be slightly lower on obscure third-party sites and Delta fares are pretty much the same on all sites.

Travel is valid on Mondays, Tuesdays, Wednesdays, and Thursdays, with departures from the USA as soon as this week, through early December, again from February through June, and from late July onward.

These fares are unadvertised and may jump in price at any time. The bigger price drops, which are only found on third-party websites, usually don't last very long so book quickly if you want to have a relatively cheap trip down under.

A sample of fares include:

Los Angeles to Melbourne $578 roundtrip, nonstop

San Francisco to Melbourne $578 roundtrip, nonstop

Los Angeles to Brisbane $584 roundtrip, nonstop

San Francisco to Sydney $586 roundtrip, nonstop

Los Angeles to Sydney $591 roundtrip, nonstop

Seattle to Melbourne $593 roundtrip

Phoenix to Sydney $598 roundtrip

Seattle to Sydney $599 roundtrip

San Francisco to Cairns $642 roundtrip

Houston to Sydney $650 roundtrip

Salt Lake City to Melbourne $652 roundtrip

Newark to Melbourne $657 roundtrip

Miami to Melbourne $657 roundtrip

Minneapolis to Melbourne $657 roundtrip

Atlanta to Sydney $664 roundtrip

Detroit to Sydney $664 roundtrip

Philadelphia to Sydney $664 roundtrip

Minneapolis to Sydney $664 roundtrip

Newark to Sydney $669 roundtrip

Los Angeles to Gold Coast $684 roundtrip

Atlanta to Brisbane $694 roundtrip

Los Angeles to Hobart $693 roundtrip

Washington D.C. to Melbourne $713 roundtrip

New York to Sydney $725 roundtrip

Dallas to Sydney $725 roundtrip

Chicago to Sydney $725 roundtrip

Dallas to Brisbane $755 roundtrip

San Francisco to Perth $821 roundtrip

Houston to Darwin $822 roundtrip

This is not a complete list. We're seeing low fares from most major hubs in the U.S. to multiple cities across Australia. For more deals to Australia, check out all of our fares to Sydney (SYD), Brisbane (BNE), and Melbourne (MEL). And if you have another Australian city in mind, it's likely much cheaper than normal.

As an example booking, I found seats departing San Francisco SFO on Tuesday, February 19, returning from Sydney SYD on Wednesday, March 6, for $586 roundtrip.