Since you are on the west coast, ordering citrus is less seasonal (based on your shipping destination of Portland). Obviously still better not to order in the "heart" of winter, but you should still probably ok. Had family who used to live in Seattle and the weather is generally fairly temperate. Few snows (even more sparse hard freezes). The almanac (and weather.com) doesn't historically show freezing for you - 36 being the low through the end of Dec. If you have a protected south facing sunny wall, you're probably ok for in ground - with some protection (cover and/or heat) below mid-upper 30s. The heat from the house and protection from the wind will do wonders. That being said, lemons and grapefruit, probably not ideal - their a bit more temperature sensitive. For sweet fruit, i'd go with the Satsuma, which should be able to be in ground for you. You should have a few weeks of upper 50s (hi) and upper 40s (lows) that would be fine to repot (if indooring) and do a few rounds of pest spray (which all have recommended and I concur).

I had all my plants outside (down to 36 a week ago here in VA). Pulled them all in when they said 35 in the forecast (then it went to 80 again). But I've had my blood oranges, cara cara, satsuma, calamodins, and lime out just fine - by accident, even through a light overnight frost. Just not a hard freeze.