1999 Weather Summary Tables

1999 Weather Summaries
Central Agricultural Research Center

Table 3. Summary of precipitation and snowfall.
Central Agricultural Research Center, Moccasin, Montana. 1999.

	Precipitation		Yearly Snowfall		Winter Snowfall*		Snow**
Month	1999	91 Yr. Avg.	1999	38 Yr. Avg.	1998-99	37 Yr. Avg.	Depth
	-------------------------------------------------------inches-----------------------------------------------------
January	0.47	0.58	14.0	12.4	14.0	12.4	7.5
February	0.24	0.46	4.7	6.9	4.7	7.0	3.0
March	0.59	0.75	8.5	11.0	8.5	11.1	4.0
April	1.24	1.15	7.7	8.2	7.7	8.5	4.5
May	1.87	2.56	2.0	1.7	2.0	1.7
June	1.80	3.19
July	1.67	1.72
August	3.55	1.61
September	1.29	1.40	0.5	0.8		0.8	0.5
October	0.26	0.87	2.0	4.4		4.5	1.0
November	0.52	0.59	2.0	7.3	7.6	7.4	1.5
December	0.11	0.56	4.0	10.4	9.0	10.6	2.5
Totals	13.61	15.44	45.4	63.1	53.5	64.0

* Winter Snowfall � Sept. 1998 thru May 1999
** Highest snow depth on the ground during the month.

Table 4. Summary of air temperature and wind velocity.
Central Agricultural Research Center, Moccasin, Montana. 1999

	1999 Air Temp. ^oF			1911-1999 Air Temp ^oF			Wind Speed MPH*
Month	Max	Min	Mean	Max	Min	Mean	1999	1910-1999

January	37	17	27.1	32.6	9.2	21.1	6.7	6.0
February	44	24	34.0	36.1	13.0	24.5	7.5	6.0
March	51	26	38.3	40.9	19.0	30.1	5.9	6.0
April	50	28	38.9	52.7	29.3	40.9	5.6	6.4
May	60	38	49.1	62.5	38.1	50.3	4.1	5.6
June	71	45	57.6	70.2	45.7	58.0	3.5	4.6
July	79	48	63.0	80.1	50.9	65.5	3.6	4.2
August	81	54	67.4	79.5	49.5	64.5	2.9	4.4
September	66	40	53.0	68.0	40.8	54.5	3.4	4.8
October	60	36	47.7	57.3	32.0	44.6	6.0	4.9
November	56	31	43.7	44.0	21.0	32.6	5.7	5.5
December	45	26	35.4	36.0	13.6	24.8	6.4	6.0

* Wind speed average of 24 hours per day.

Number of days 90 F or above in 1999

June	July	Aug	Sept	Total	89 Yr. Avg.
0	6	4	0	10	10

Number of days 0 F or under in 1999

Jan	Feb	Mar	Apr	Oct	Nov	Dec	Total	89 Yr.Avg.
3	0	0	0	0	0	0	3	27

Lowest temperature recorded in 1999: -14 ^oF, January 24, 1999
Highest temperature recorded in 1999: 99 ^oF, July 29, 1999
Date of highest wind speed in 1999: 15.0 MPH, December 19, 1999

Table 5. Summary of soil temperature at three soil depths under bare ground and sod.
Central Agricultural Research Center, Moccasin, Montana. 1999

	4 � Soil Depth		8 � Soil Depth		20 � Soil Depth		4 � Soil Depth
	Bare Ground		Bare Ground		Bare Ground		Under Sod
	1999	34 Yr.	1999	34 Yr.	1999	24 Yr.	1999	34 Yr.
	Mean	Mean	Mean	Mean	Mean	Mean	Mean	Mean

January	32.7	30.8	34.7	31.1	36.0	34.0	34.6	32.1
February	31.9	32.2	33.4	31.8	35.0	33.1	34.3	32.5
March	39.9	37.1	38.4	35.6	37.0	34.9	39.8	37.9
April	44.8	45.8	44.2	43.7	42.0	40.6	46.8	47.1
May	55.6	56.7	53.0	54.1	48.0	48.6	55.1	57.5
June	66.2	66.7	63.6	63.7	56.0	56.2	65.4	66.6
July	72.3	74.2	69.2	71.1	61.0	62.0	70.0	73.0
August	73.6	72.8	71.0	70.3	64.0	63.5	71.5	72.1
September	59.3	61.3	59.0	60.0	58.0	58.5	59.3	61.7
October	48.5	48.2	48.6	48.1	50.0	50.6	49.9	50.0
November	42.1	37.5	43.2	38.4	46.0	42.9	44.5	40.5
December	33.0	33.0	35.2	33.7	40.0	37.5	35.7	34.8

Low and high soil temperature during winter (1998-99) and summer 1999

	Low (^oF)		High (^oF)
4 inch bare	25	Jan. 24	102	Aug. 3
8 inch bare	33	Jan., Feb., & Mar.	82	July 29
20 inch bare	35	Jan., Feb., & Mar.	65	July 29-31 and numerous days in Aug.
4 inch sod	32	Dec. 25, 30 & Feb. 14-15	82	July 28-29, Aug. 3 & 11

Dates soil first froze (32 ^oF) and dates last thawed 3 days (33 ^oF) winter 1998-99.

	Froze	Thawed
4 inch bare	Dec. 21	March 7
8 inch bare	Did not freeze
20 inch bare	Did not freeze
4 inch sod	Dec. 25	Feb. 16

Table 6. Inches of evaporation from a free water surface.
Central Agricultural Research Center, Moccasin, Montana. 1999.

	Water Evap. � inches		Precipitation � inches
Month	1999	1909-99	1999	1909-99

April	2.90	4.10	1.24	1.15
May	3.51	5.93	1.87	2.56
June	7.54	6.72	1.80	3.19
July	12.29	8.90	1.67	1.72
August	9.16	8.50	3.55	1.61
September	5.95	5.60	1.29	1.40

Ratio of Precipitation to Evaporation

1999: 1 inch precipitation to 3.62� evaporation
1909-1999: 1 inch precipitation to 3.70� evaporation

Highest daily evaporation in 1999: 0.85� on August 19, 1999

Table 7. Summary of growing degree units.
Central Agricultural Research Center, Moccasin, Montana. 1999.

		GDU*		Mean Air Temp ^oF
Month		1999	1911-99	1999	1911-99

	May	178	207	49.1	50.1
June		316	313	57.6	57.9
July		438	490	63.0	65.4
August		536	475	67.4	64.6
September		254	286	53.0	54.5
October		177	161	47.7	44.8
Total		1899	1932

*GDU = (max. temp. + min. temp.)/2 � 50
If max. temp. > 86, substitute it with 86
If min. temp. < 50, substitute it with 50

The 50-86 degree temperature range is considered the optimum growth range for corn. Temperatures above or below these limits can slow development and growth. GDU is used as a method of rating plant maturity. The more heat units, the faster plants will grow. Some research has shown that a 40-90 degree temperature range is more normal for most small grains. GDU is figured on a daily basis and added to previous days� totals.

Precipitation

Yearly Snowfall

Winter Snowfall*

Month