Volunteer weather observer John Beltz’s summary for May proves what we already knew: May was a lot wetter and a little cooler than normal.
According to Beltz, it rained in Jefferson on 18 days in May for a total of 6.46 inches. Two rainfalls were well over an inch – 1.43 inches on May 17 and 1.38 inches on May 27. Normal rainfall for May is 4.14 inches.
It was also cooler than normal. Average high temperature for the month was 69.7 degrees; 72.4 degrees is normal. The temperature was 80 degrees or warmer on just three days. The high temperature was in the 60s or cooler 12 days. The nights were just a bit warmer than normal. Average low temperature was 49.0 degrees; average is 48.3 The low temperature was in the 40s or cooler on 16 nights in May.
High temperature for the month was 85 degrees on May 4. Record high temperature for May in Jefferson is 104 degrees on May 30, 1934. Low temperature for the month was 36 degrees on May 19 and May 20. Record low temperature is 19 degrees on May 2, 1961, and on May 4, 1907.
Farmers watch growing degree days, a computation of the maximum temperature + the minimum temperature, divided by 2, and then subtract 50 from the quotient. In figuring the GDD, if the high temperature is greater than 86 degrees, 86 is used for the high. If the low temperature is below 50, then 50 is used for the low.
Beltz calculated 351 growing degree days for May. Normal is 434.
