New Zealanders coming to live in America have quite a roller-coaster ride waiting for them, especially if they end up east of the Rockies and north of the Deep South! Summer in much of the USA is like living in the tropics, with high humidity and temperatures frequently topping 100 degrees Fahrenheit (38 degrees Celcius). Winter brings Arctic weather, with temperatures in places like Chicago easily falling below minus 20 degrees Celcius. Downtown, people are often seriously injured or killed by icicles falling from skyscrapers.
You can blame this weather on America's "continental climate". Unlike New Zealand, whose weather is moderated by the large oceans on all sides, the continental United States is dominated by large land masses, which allow winds from the north or south to travel for great distances, bringing cold or hot air with them. Cold fronts can bring snow on the same day as 80 degree (27 degree Celcius) temperatures, as I experienced one day in New Jersey!
Fall is one of the more pleasant seasons of the year, with mild temperatures and clear skies. When the leaves start to change color, hundreds of thousands of spectactors, known in some places as "leaf peepers", travel north, or seek out the mountainous areas of their own state. In some places, this tourist activity is a major part of the local economy, at least for three or four weeks of the year. Wherever this spectacle occurs, local television stations show maps of where the color is most vivid, just as the Japanese chart the steady progress northward of the cherry blossom, and Indians follow the monsoon as it advances up the country. I took time out while I was in New Jersey to visit the Delaware Water Gap at this time, and you can see the Fall foliage at some of its lakes.