Whenever the weather seems unseasonably extreme in one direction or the other, I find myself wondering how it compares to years past. This recent summer in Connecticut started off with several rainy weekends that potentially biased my opinion, so I downloaded weather data from NOAA to check. The precipitation data shown in the chart above and Table below are from 1950 through 2021 as measured at Bradley Airport in Hartford. With roughly 22 inches of rain falling between June 1st and August 31st, this past summer was one of the wettest included in this data set.
2021 ranks as the 3rd wettest since 1950. If I stretched the time boundary by just a few hours, it could be considered the second wettest because Hartford received an additional 4 inches of rain in the early AM hours of September 1st thanks to Hurricane Ida. The wettest summer in this data set occurred in 1955 when hurricanes Diane and Connie dumped roughly 22 inches of rain in just over a week.
The data are normally distributed, about an approximate 10 inch mean, and skewed right by extreme weather. The Table lists monthly totals for eight summers when precipitation exceeded 19 inches. Perhaps you can recall hurricane Irene which accompanied the second wettest August with 11.7 inches of precipitation in 2011.
NOAA has a variety of environmental data, so along with the precipitation data, I downloaded daily min/max temperature readings to compare this summer’s temperatures to those experienced several decades ago. The temperature chart is a slight variation to the chart explained in my post about visualizing temperature data with python. The graph compares the current summer’s temperatures, daily minimum and maximum readings measured at Bradley, to a specific date range of temperatures measured in the same location. In this chart, 2021 summer temperatures are compared to summer temperatures from 1960-1969. Note that there are 10 minimum and 10 maximum daily temperature pairs for each day listed on the x-axis, but the chart uses only the highest max and lowest min to set the daily range outlined by the black lines. This summer’s temperatures are plotted, as red or blue dots, if they exceed that range 1960’s range. Based on the small number of blue and red dots, this summer’s temperatures were uneventful.
In looking at both precipitation and temperature readings, I noted something that seems obvious after seeing it in the data. Although Connecticut is small, two separate but relatively close weather stations can have precipitation data that differ dramatically as compared to their temperature data. At first I was skeptical of the data’s accuracy when I found much lower precipitation values for Danbury. It’s not unusual that a weather station may have a missing or bogus data points on some days, especially over a 70 year span. However, considering it further, it’s also typical of summer storms that it will rain much harder on one side town as compared to the other, just a few miles away. It’s easier to escape heavy rain in your car than it is to drive in search of hotter or cooler weather. For Hartford, this has been one of the wettest summers since 1950, but if you live in Danbury, your experience may have been much more average.
Glenn DiCostanzo
September 14, 2021