I live in New Zealand.
Honestly, we have an odd relationship to Christmas. We have adapted Northern Hemisphere traditions to summer, but only partially and awkwardly. It's all a bit odd and culturally schizophrenic.
So, we still have plenty of Christmas decorations themed around snow and robins and holly. Christmas displays inside malls will have fake snow. We watch all the same Christmas movies the rest of the world does. But there'll also be some hokey decorations showing Santa wearing shorts and surfboarding, or snowmen on the beach, things like that.
The older folk still enjoy Christmas cake, pudding, roast turkey and so on, but those foods really don't sit well on a hot day! So most people have ham rather than turkey, or do a BBQ (which down here is like grilled meat, not like southern-style BBQ). For obvious reasons mulled wine and hot chocolate isn't much of a thing here, and eggnog hasn't really caught on either (although I make Alton Brown's Aged Eggnog and three people so far have caught the tradition because it's so good!)
Strawberries are very good in NZ - big and juicy and sweet. Strawberries scream 'Christmas' to me, and going to a pick-your-own berry farm is a fun summer activity. So is getting a 'real fruit ice cream', which is vanilla ice cream or frozen yoghurt blended up with frozen berries and piped soft serve-style into a waffle cone. Pavlova is a popular Christmas dessert, and that usually has strawberries on it as well.
In general we don't decorate as lavishly as the US or Europe. Some fancier neighborhoods have Christmas lights, and you can walk or drive around to see them - but because summer evenings are so long, it's past the kids' bedtimes before it gets dark! (See also: Guy Fawkes' Day. It's a problem.)
Families go to the beach a lot around Christmas. Camping is pretty popular. The long warm evenings are good for end-of-year work parties and picnics.
I have spent one almost-Christmas in the Northern Hemisphere, visiting England in early December. It was absolutely magical, and felt 'right' in quite a profound way. It wasn't snowing, but the cold and Christmas markets and lit-up streets and old-fashioned architecture were far more legit and picturesque than anything we have down here.
That said, I love Christmas, and the lengthening evenings, hot days and growing veggie garden are very evocative in their own way. I've often wondered whether I'd get that Christmas feeling if I visited the Northern Hemisphere during summer!