Daily high temperatures, such as a balmy Christmas Day in Rochester, often attract attention, including headlines from us.
However, warm nighttime temperatures are better indicators of our warm climate, as nights are warming faster than days in most parts of the United States, according to the 2023 National Climate Assessment. The number of nights with a minimum temperature of 70 degrees or higher is increasing Everywhere in the United States except the northern Great Plains and Alaska.
The nighttime temperature in Rochester on December 28 caught the attention of Climate Central, a nonprofit group of scientists and communications specialists.
The temperature was 20 degrees higher than normal. This is an unusual swing.
Climate Central's Climate Transition Index marked last Thursday evening as unusually warm — and attributed the extreme temperature to the climate crisis. The low temperature for the day was 42 degrees, just 7 degrees lower than the high temperature, and about 20 degrees warmer than the average low temperature, according to the National Weather Service in Buffalo.
So what is the Climate Transition Index? It is a rating scale, ranging from -5 to 5, that determines the impact of climate change on the temperature on a given day.
The nighttime temperature in Rochester on December 28 was 4 degrees Celsius, which is considered an “extreme” on the Climate Transition Index.*
It's snowing less in Rochester now
Warmer winter days have increased since 1970, with an average of 15 more days of above-average temperatures now, according to Climate Central. The effect is evident in our rainfall totals in December.
While the Weather Service's Dec. 29 climate summary showed precipitation totals for the month slightly above normal (2.8 inches to 2.5 inches), the amount of snowfall lagged well behind standards.
There were 5 inches of snow total in December, which is 15.7 inches below normal.
It should be familiar, though. Rochester only had 4.8 inches of snowfall in December of last year, while also seeing less than normal precipitation. Last winter, only 50.7 inches of snow fell, well below the average of about 100 inches.
more:It's an El Niño winter. What this means for Rochester.
more:When is the winter solstice? The longest night in Rochester is coming
Details: Climate model tracks global warming
*The Climate Center's Climate Transition Index describes the classification as common conditions occurring as a result of at least a four-fold change in climate; The same conditions would be extremely rare without it.
- In the explanation on its website, Climate Central explains that the index does not mean that climate change caused hot weather on any given day, but that it attempts to use the analytical models that support it to explain how climate change has made those temperatures more likely.
- Negative numbers on the Climate Transition Index scale indicate how low the probability of a temperature event occurring due to climate change is.
– Steve Howe covers weather, climate and lake issues for the Democrat and Chronicle and he's ready for some snow. Do you have any idea how the weather changes in winter? Share with him at showe@gannett.com.
