Everyone instinctively knows the difference between weather and climate. Both involve things like temperature, rain, snow, clouds, and wind. But weather is short-term: it applies to what’s going on day to day, or even hour to hour. Climate is long-term: it describes the average conditions in a particular region over many years. That’s why a single weather event can never prove or disprove the reality of human-caused climate change.
Weather can change very quickly as weather systems sweep across the country. It might be sunny and warm one day, then cool with torrential rains the next. Climate can’t change like that. January in northern Vermont is about 52°F colder, on average, than July. If you want a place that’s warm year-round, you don’t go to Vermont. Vermont has cold winters: that’s how it was last year, and you can count on it being that way next year, even though the temperature might change by a few degrees up or down from one year to the next.
But while Vermont winters are always a lot colder than Vermont summers, the day-to-day weather can bounce around quite a bit. The climate in Minneapolis, Minnesota, is frigid in winter and warm in summer. That doesn’t mean we will never get a warm day in winter. The thermometer hit a record 64° one day in February 1896 and plunged to 39° in August 1967. Washington, D.C., doesn’t usually get bad snowstorms, but in the winter of 2010 it got several of them. All of that is weather, not climate.
Climate can change too, but much more slowly. The average temperature or precipitation in any location might creep up or down over a period of decades, but the weather is always going to change more day to day than the climate changes year to year. A 100° day in New York in July is hotter than average, but by itself it doesn’t mean the climate is getting warmer. A string of 100° days in New York in July doesn’t necessarily mean the climate is getting warmer.
But if New York keeps getting more record-high temperatures decade after decade and fewer record-low temperatures, that’s a hint that the climate might really be changing.