I’m temporarily in the USA but normally live in another country; can I apply for an Irish passport here?

No, you must apply in the country where you are normally resident.

You should only apply to the Passport Office at Consulate of Ireland San Francisco if you reside in Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming, or in the case of a lost/stolen passport while visiting here.