First Alert Weather In-Depth: How climate trends shape today’s weather ‘normals’

ROCHESTER, N.Y. – Every day, we present a variety of weather data including highs, lows, record temperatures, sunrise and sunset times, and more. One piece of information we do not highlight as often, however, is the normal temperature. So, what exactly is a “normal” high or low for this time of year?

If you have been following the weather over the past couple of weeks, you have probably noticed temperatures bouncing all over the place. With that kind of variability, how do we come up with anything that can reasonably be called normal?

The National Oceanic and Atmospheric Administration (NOAA) defines a “normal” temperature as using a 30-year dataset. By measuring and averaging daily temperatures over that long period, short-term extremes like unusually warm or cold years will tend to smooth out the extremes. At the same time, this method still captures long-term trends, including the gradual warming we have observed over recent decades. These rolling 30-year calculations are updated regularly, giving us an up-to-date reference point for any given day.

It is also important to note that “normals” are not limited to temperature. They can include other climate variables such as rainfall and snowfall. For example, the typical or “normal” snowfall for January is just over 27 inches. That number does not mean every January will behave that same way, but it does provide a valuable benchmark to help us understand how the days conditions compare to the long-term average.