My friend and colleague Deke Arndt, a climatologist at the National Centers for Environmental Information, recently published a series of graphs showing how distributions of temperature have changed over time. On these graphs, each line represents a different month. The blue “hump” shows the distribution of daily temperature (either maximum or minimum) for the period from 1959 to 1988. The red “hump” shows the distribution of temperature for the period 1989-2018, also a 30 year period. You can see by looking at the graphs below that the more recent temperatures are shifted to the right compared to the early record. In the case of Miami (shown here), every month the maximum temperatures are significantly shifted towards higher temperatures, but it is especially noticeable in the summer months. Other cities show the same pattern, although most are not quite as obvious as Miami’s pattern. This shows that over time, our temperatures are gradually shifting upwards, although on any day you could be colder than average because weather is not the same as climate. With the shift in the distribution, it makes it much easier to break record high temperatures and much harder to break record cold temperatures.
