Is it safe for my partner to travel to Thailand with a passport expiring shortly after our return?

And you can normally get same day if you bring it in first thing..need to bring copy of itinerary too

Depending on where you live, there might be a US passport office close to you…better than mailing the passport in

Get a new passport

I'd get an emergency passport.

Not worth it too many horror stories. It's not too late for expedited passport. But you'll have to use a private company not the post office. It will cost but you'll have it in time!

Why take the chance get a new passport

My daughter had a ticket to Italy to visit a friend. She flew domestic to NYC and the airline would not allow her to board the international flight because her passport expired in 4 months. Subsequently she lost her airfare and acquired unforseen expenses with regard to local accommodations and transportation back to her hometown. IMO your partner needs to apply for an expedited passport, if that is possible.

Thailand doesn't have a 6 month validity rule for flying there. You cannot purchase a visa from a consulate in your home country unless your passport has at least 6 months left, but if you are entering visa exempt that's not an issue.

The problem is that there is a very high chance your airline will not allow them to fly.

Many countries do have a 6 month rule, and most airline staff just apply it to everywhere. They have the final say on if you can fly or not, so you need to check with them. But if you're able to get to Thailand, just have proof that you'll be leaving within your 30 day visa exempt and before the passport expires and it shouldn't be an issue.