Is 2 hours transit time in SFO enough for a NZ-citizen flying Kelowna,BC - SFO - Auckland?

Unlike Vancouver, you do NOT pre-clear US customs in Kelowna - you'll be doing it on arrival in SFO. So naturally this will take more time.

However, if your flights are all on the same ticket (booking reference etc), the airline must feel it's a valid connection, and you should be fine - if you're not, they'll have to rebook you.

However, if you don't want that hassle (next flight to Auckland may be a day later, or worse), or you have separate tickets, or think it may take longer for you to go through (do you have a snowboard bag etc?), or are concerned that you may be late leaving Kelowna (weather, for example), then you may want to try and make an earlier flight from Kelowna.

SFO is a really nice airport (in my opinion - I've even slept overnight in it), it's nothing like the transit nightmare that is LAX, but if there's a long queue you may still be cutting it really fine to get through, given you have to go through US immigration once you arrive, even for a 'transit' flight.

(source: NZer myself, with experience transiting in LAX enroute to Auckland, and I've had several flights in/out of SFO, although not internationally connecting there).

Additional source: Australian Frequent Flyers: they note that fog can be a big problem at SFO, and if you can't land you may miss a connecting flight. Suggestions there are 3 hours minimum.

As a US citizen I wouldn't book a 2 hour connection in SFO, period. It has nothing to do with the formalities (although the last time I was through there it was nearly an hour in the immigration line--for some reason they had only half the booths open) but rather the weather.

Some years ago a ~90 minute connection went bad due to weather, we did just barely make it but our seats had been given away as no-shows. They still had seats, we did fly.

Two months ago we had another ticket with a ~90 minute connect (I knew better, my wife didn't realize the problem) and was proactive about it--we showed up at the airport early enough to catch an earlier flight. The agent understood the situation and was quite willing to move us to the earlier bird. Big delays but the extra two hours got us on it. When we landed I saw that the bird we were scheduled on was delayed, expected arrival almost exactly when our connecting flight would depart.

The basic problem is that there are two parallel runways at SFO that work fine under visual rules but when visibility drops the approach patterns are too close for instrument rules--airport capacity gets cut in half.

Note that weather delays are your problem, you are not owed any compensation. So long as you have one ticket they'll get you to Auckland eventually but you'll pay your own hotel etc while you're waiting for a seat.