Summary of climatic data by months for the 2017-2018 cropping year (September-August) compared to averages for the period of record from
1911 to 2017 at the Southern Agricultural Research Center near Huntley, Montana.
2017 2018
Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Year
Precipitation (inches) Total
Current Year (2017-2018) 2.57 0.37 1.17 1.14 0.58 1.82 0.90 2.70 3.81 3.77 0.87 2.00 21.70
Average (1911-2016) 1.30 1.07 0.64 0.59 0.55 0.45 0.79 1.34 2.18 2.33 1.14 0.94 13.32
Difference +1.27 -0.70 +0.53 +0.55 +0.03 +1.37 +0.11 +1.36 +1.63 +1.44 -0.27 +1.06 +8.38
Mean Temperature (ºF) Average
Current Year (2016-2017) 58.6 47.0 33.6 23.4 19.6 9.9 29.3 40.7 59.1 63.4 70.2 67.8 43.6
Average (1911-2016) 58.0 46.9 33.6 23.9 20.7 25.7 34.3 45.5 54.9 63.3 70.8 68.8 45.5
Difference +0.6 +0.1 0.0 -0.5 -1.1 -15.8 -5.0 -4.8 +4.2 +0.1 -0.6 -1.0 -1.9
Last Killing Frost in Spring
1/
2018 ...................................................... 32ºF on April 25
Average (1911-2017) ........................................... May 17
First Killing Frost in the Fall
1/
2018 ............................................. 30ºF on September 21
Average (1911-2017) ................................ September 19
Frost-free Period 2018 .................................................................... 141 days
Average (1911-2017) ......................................... 125 days
Growing Degree Days (Base 50)
2/
2018 ......................................................... 2,138 GDD (ºF)
Average (1911-2017) .............................. 2,009 GDD (ºF)
Growing Degree Days (Base Corn)
2/
2018 ........................................................ 2,199 GDD (ºF)
Average (1911-2017) ............................. . 2,219 GDD (ºF)
Maximum Summer Temperature 100ºF on August 11, 12, and 13, 2018
Minimum Winter Temperature -29 ºF on February 10 and 20, 2018
1/ 32 ºF is considered a killing frost. Average last and first killing frost dates are calculated on a 50% probability of a minimum temperature occurring below the threshold temperature
of 32.5 ºF based on observations from 1911 to 2017.
2/ Growing degree days calculated from temperatures observed during the frost free period from April 25 through September17, 2018, and for the same 145-day interval from the
period of record of 1911 to 2017.
