“climate is not the weather—a distinction often missing in popular discussion. The weather anywhere varies constantly in ways both predictable and unexpected—through the day (it’s usually warmer at 4 pm than it is at 4 am), across days (as when a front passes through), with the seasons, and from year to year. On the other hand, a location’s climate is the average of its weather over decades. In fact, the UN’s World Meteorological Organization defines climate as a thirty-year average, although climate researchers will sometimes discuss averages over a period as short as ten years. So changes in the weather from one year to another do not constitute changes in climate.”