Southern Agricultural Research Center | Montana State University

Summary of Climatic Data by Month September 2020 - August 2021 at the Southern Agricultural Research Center, Huntley, MT
Month	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Year
Year	2020	2020	2020	2020	2021	2021	2021	2021	2021	2021	2021	2021
Precipitation (inches)													Total
Current Year	0.55	2.06	0.23	0.32	0.27	6.29	0.58	1.20	1.92	0.38	0.13	1.49	15.42
Average (1911- 2020)	1.35	1.10	0.63	0.61	0.54	0.47	0.80	1.37	2.251	2.36	1.11	0.97	13.54
Difference	-0.80	+0.96	-0.40	-0.29	-0.27	+5.82	-0.22	-0.17	-0.29	-1.98	-0.98	+0.52	+1.88
Temperature (°F)													Average
Current Year	60.3	40.4	35.4	30.4	29.1	13.6	38.1	43.8	52.7	70.1	75.9	66.6	46.4
Average (1911 - 2020)	58.2	46.9	33.7	23.9	21.1	25.8	34.4	45.5	55.0	63.5	70.9	68.8	45.6
Difference	+2.1	-6.5	+1.7	+6.5	+8.0	-12.2	+3.7	-1.7	-2.3	+6.6	+5.0	-2.2	+0.8

Last killing frost in spring^a: 2021: May 6 (32.0 °F); Average (1911 - 2020): May 6
First killing frost in fall^a: 2021: September 17 (25.0 °F); Average (1911 - 2020): Septembper 19
Frost-free period: 2021: 134 days; Average (1911 - 2020): 126 days
Growing Degree Days (Base 50)^b: 2021: 2263 GDD °F; Average(1911-2020): 2096 GDD °F
Growing Degree Days (Base Corn)^b: 2021: 2217 GDD °F; Average(1911-2020): 1957 GDD °F
Temperature Extremes: Maximum summer temperature: 108 °F (July 20, 2021); Minimum winter temperaturege -36 °F (February 13, 2021)

^aIn this summary 32 °F 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 2020.

^bGrowing degree days calculated from temperatures observed during the frost free period from May 6th through September 17th, 2021, and for the same 134-day interval from the period of record of 1911 to 2020.