Malheur Experiment Station Information for Sustainable Agriculture

Air temperature and precipitation have been recorded daily at the Malheur Experiment Station since July 20, 1942. Installation of additional equipment in 1948 allowed for evaporation and wind measurements. A soil thermometer at 4-inch depth was added in 1967. A biophenometer, to monitor degree days, and pyranometers, to monitor solar and photosynthetically active radiation, were added in 1985.

Since 1962, the Malheur Experiment Station has participated in the Cooperative Weather Station system of the National Weather Service. The daily readings from the station are reported to the National Weather Service forecast office in Boise, Idaho.

On June 1, 1992, in cooperation with the U.S. Department of the Interior, Bureau of Reclamation, a fully automated weather station, connected by satellite to the Northwest Cooperative Agricultural Weather Network (AgriMet) computer in Boise, Idaho, began transmitting data from Malheur Experiment Station. The automated station continually monitors air temperature, relative humidity, dew point temperature, precipitation, wind run, wind speed, wind direction, solar radiation, and soil temperature at 8-inch and 20-inch depths. Data is transmitted via satellite to the Boise computer every 4 hours and is used to calculate daily Malheur County crop water-use estimates. The AgriMet database can be accessed via computer modem or through the internet at www.pn.usbr.gov/agrimet and is linked to the Malheur Experiment Station web page at www.cropinfo.net.

Starting in June 1997, the daily weather data and the monthly weather summaries have been posted on the Malheur Experiment Station web site on the internet at www.cropinfo.net.

The ground under and around the weather stations had been bare, but was covered with turfgrass on October 17, 1997. The grass is irrigated with subsurface drip irrigation. The weather data is recorded each day at 8:00 a.m.

Evaporation is measured from April through October as inches of water evaporated from a standard 10-inch-deep by 4-ft-diameter pan over 24 hours. Evapotranspiration (Et) for each crop is calculated by the AgriMet computer using data from the AgriMet weather station and the Kimberly-Penman equation (Wright 1982). Reference Et is calculated for a theoretical 12- to 20-inch-tall crop of alfalfa assuming full cover for the whole season. Alfalfa peak Et is calculated for an alfalfa crop that is kept uncut during the season. Alfalfa mean Et is calculated for an alfalfa crop assuming a 15 percent reduction to account for cuttings. Alfalfa peak Et would be the same as reference Et when the alfalfa reaches full cover. Evapotranspiration for all crops is calculated using the reference Et and factors for each crop that vary during the season depending on the degree of cover.

Wind run is measured as total wind movement in miles over 24 hours at 24 inches above the ground. Weather data averages in the tables refer to the years preceding and up to, but not including the current year.

The total precipitation for 2001 was lower than the 10-year and 55-year averages and was the lowest in the last 10 years (Table 1).

The months of May and August had a higher number of growing degree days (50° to 86°F) than the 15-year average (Table 2). The total number of growing degree days in 2001 was close to the 15-year average (Table 2). The total number of growing degree days in 2001 was closer to the 10-year average when compared to the highest (1994) and lowest (1993) years since 1990 for growing degree days (Fig. 1). May had substantially more degree days in the above optimal range (86° to 104°F) than the previous 10-year average (Table 3). The total number of degree days in the above optimal range in 2001 was close to the previous 10-year average.

The months of January and February had total wind runs 53 and 22 percent lower, respectively, than the 10-year average (Table 4). The months of November and December had total wind runs 33 and 40 percent higher, respectively, than the 10-year average. November 29, 2001 had the highest wind run since October 1990. Total pan-evaporation for May was 16 percent higher than the 10-year average and 31 percent higher than the 53-year average (Table 5). Total pan-evaporation for 2001 was close to the 10-year and 53-year averages.

Total Et for all crops in 2001 was slightly higher than the 9-year mean (Table 6).

Mean monthly air temperatures were close to the 10-year and 53-year average (Table 7).

From March through October the mean monthly maximum and minimum 4-inch soil temperatures were lower than the 10-year and 34-year average (Table 8). The difference in soil temperature between 2001 and the mean is probably influenced by the installation of turf around the weather station in October of 1997. The soil remained warmer in winter and cooler in spring and summer. The last spring frost ([32°F) occurred on April 29, 1 day later than the 25-year average date of April 28; the first fall frost occurred on October 10, 6 days later than normal (Table 9).

The weather in 2001 did not exceed any record weather events recorded over the 57-year history for the Malheur Experiment Station (Table 10). The highest temperature for the year was 103°F on July 5 (Table 6). The lowest temperature for the year was 10°F on January 27 and February 2. Total precipitation was 7.78 inches for the year, the lowest since 1991 and 28 and 25 percent lower than the 10-year station average and the 55-year station average (Table 1). Total pan-evaporation for April through October was 58.3 inches, close to the 10-year average and slightly higher than the 53-year average (Table 4). Total snowfall for 2001 was 15.5 inches, slightly lower than the 10-year and 58-year average (Table 11).

Wright, J.L. 1982. New evapotranspiration crop coefficients. J. Irrig. Drain. Div., ASCE 108: 57-74.

Table 1. Monthly precipitation at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2001.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
	----------------------------------------------------- inches -----------------------------------------------------
1991	0.59	0.44	0.88	0.81	1.89	1.09	0.01	0.04	0.35	1.01	1.71	0.43	9.25
1992	0.58	1.36	0.25	0.74	0.21	1.43	0.36	0.01	0.09	0.95	1.15	1.51	8.64
1993	2.35	1.02	2.41	2.55	0.70	1.55	0.18	0.50	0.00	0.80	0.64	0.60	13.30
1994	1.20	0.57	0.05	1.02	1.62	0.07	0.19	0.00	0.15	1.23	2.46	1.49	10.05
1995	2.67	0.28	1.58	1.16	1.41	1.60	1.10	0.13	0.07	0.57	0.88	2.56	14.01
1996	0.97	0.86	1.03	1.19	2.39	0.12	0.32	0.31	0.59	0.97	1.18	2.76	12.69
1997	2.13	0.17	0.25	0.66	0.67	0.86	1.40	0.28	0.40	0.43	1.02	0.94	9.21
1998	2.26	1.45	0.95	1.43	4.55	0.36	1.06	0.00	1.00	0.04	1.07	1.11	15.28
1999	1.64	2.50	0.59	0.23	0.28	1.02	0.00	0.09	0.00	0.40	0.49	0.73	7.97
2000	2.01	2.14	0.97	0.72	0.28	0.26	0.03	0.06	0.39	1.74	0.38	0.66	9.64
2001	1.15	0.41	1.11	0.70	0.37	0.64	0.32	0.00	0.10	0.68	1.33	1.00	7.78
10-yr avg	1.64	1.08	0.90	1.05	1.40	0.84	0.47	0.14	0.30	0.81	1.12	1.28	10.80
55-yr avg	1.37	0.99	0.95	0.81	1.07	0.79	0.26	0.40	0.50	0.71	1.17	1.32	10.32

Figure 1. Cumulative growing degree days (50-86°F) over time, Malheur Experiment Station, Oregon State University, Ontario, OR.

Table 2. Monthly total growing degree days (50-86°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2001.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
1991	0	13	16	124	212	389	776	718	436	194	1	0	2,879
1992	0	13	106	202	482	574	639	704	385	174	4	0	3,283
1993	0	0	23	81	423	358	464	524	408	252	6	0	2,539
1994	0	2	92	189	369	523	794	774	509	144	2	0	3,398
1995	0	29	32	106	293	433	680	588	472	101	3	10	2,747
1996	0	5	53	135	243	446	805	658	364	194	18	2	2,923
1997	4	0	81	117	419	509	661	706	481	157	20	0	3,154
1998	0	2	52	112	68	571	802	749	515	151	16	4	3,042
1999	0	2	43	72	329	459	683	703	416	184	30	0	2,921
2000	0	4	36	194	342	536	751	743	368	133	2	0	3,109
2001	0	0	63	126	401	488	715	761	472	155	27	0	3,208
15 year avg	0	7	54	155	319	508	715	681	432	169	12	1	3,053

Table 3. Monthly total degree days (86 -104°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2001.

Year	Apr	May	Jun	Jul	Aug	Sep	Oct	Total
1991	0	0	2	41	36	4	0	83
1992	0	5	20	23	54	2	0	104
1993	0	4	4	2	11	5	0	26
1994	0	2	16	68	54	7	0	147
1995	0	0	4	23	22	7	0	56
1996	0	0	5	54	32	4	0	95
1997	0	4	0	27	31	5	0	67
1998	0	0	0	63	45	14	0	122
1999	0	1	2	21	16	1	0	41
2000	0	0	7	41	43	4	0	95
2001	0	5	7	25	45	4	0	86
10-yr avg	0	1	7	40	37	6	0	91

Table 4. Daily wind-run totals and monthly totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2001.

Daily	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	------------------------------------------- miles -----------------------------------------------
Max.	89	237	227	155	169	163	93	114	164	118	405	268
Min.	2	9	16	37	26	27	32	19	21	21	24	2
Average	24	50	68	73	83	72	62	53	53	52	71	76
Annual total	-------------------------------------------- miles ------------------------------------------------
2001	747	1,387	2,121	2,203	2,587	2,147	1,924	1,635	1,586	1,625	2,120	2,357
10-yr average	1,576	1,780	2,378	2,481	2,340	1,988	1,807	1,704	1,639	1,798	1,595	1,682
53-yr average				2,144	1,924	1,560	1,473	1,325	1,257	1,283

Table 5. Pan-evaporation totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2001.

Totals	April	May	Jun	Jul	Aug	Sep	Oct	Total
Daily	-------------------------------------- inches ---------------------------------------
Mean	0.18	0.32	0.33	0.35	0.34	0.24	0.14
Max.	0.30	0.50	0.49	0.50	0.50	0.42	0.32
Min.	0.03	0.08	0.14	0.18	0.22	0.09	0.03
Annual	---------------------------------------- inches ------------------------------------
2001	5.45	10.03	10.03	10.88	10.48	7.15	4.28	58.30
10-yr avg	6.04	8.64	9.37	11.46	10.80	7.54	4.40	58.25
53-yr avg	5.59	7.64	8.86	11.12	9.60	6.27	3.20	52.28

Table 6. Total Et (acre-inches/acre), Malheur Experiment Station, Oregon State University, Ontario, OR, 1992-2001.

Year	Reference Et	Alfalfa (peak)	Alfalfa (mean)	Spring grain	Sugar beet	Onion	Potato - Shepody	Potato	Field corn
1992	50.6	51.8	44.5	28.6	34.8	30.6	32.6	27.6	29.2
1993	44.1	42.5	36.7	22.4	29.5	24.2	22.4	22.9	24.5
1994	50.0	47.4	40.7	23.2	34.5	29.6	22.5	28.0	28.6
1995	44.8	43.4	37.2	23.1	29.0	25.6	24.7	24.1	24.3
1996	47.7	46.4	39.8	23.7	33.0	28.0	25.1	27.1	26.7
1997	49.5	48.3	41.6	25.8	33.4	28.0	24.7	28.3	26.2
1998	49.2	47.4	40.6	24.6	32.5	28.2	25.1	27.1	27.9
1999	53.1	51.3	44.0	25.7	33.8	29.5	26.7	28.0	28.6
2000	54.8	53.2	45.6	25.8	38.3	32.5	27.3	30.4	29.7
2001	52.8	51.2	43.8	27.3	34.8	30.1	27.8	28.0	28.0
9-year avg	49.3	48.0	41.2	24.8	33.2	28.5	25.7	27.1	27.3

Table 7. Monthly air temperature, Malheur Experiment Station, Oregon State University, Ontario, OR, 2001.

	Jan		Feb		Mar		Apr		May		Jun		Jul		Aug		Sep		Oct		Nov		Dec
	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min
	---------------------------------------------------------------------- oF ----------------------------------------------------------------
Max.	40	32	49	32	72	44	83	50	97	66	97	63	103	72	102	71	93	58	85	52	64	45	45	33
Min.	22	10	30	10	43	22	42	24	60	34	63	42	73	48	79	48	70	38	53	28	35	22	23	17
2001 avg	33	22	40	25	58	34	61	37	77	47	81	52	90	59	93	59	83	49	66	39	52	32	36	25
10-yr avg	37	24	45	27	56	32	64	37	74	46	80	51	90	57	91	54	81	46	66	36	47	28	37	23
58-yr avg	35	20	43	25	55	31	64	37	74	45	82	52	91	57	90	55	80	46	66	36	48	28	37	22

Table 8. Monthly soil temperature at 4-inch depth, Malheur Experiment Station, Oregon State University, Ontario, OR 2001.

	Jan		Feb		Mar		Apr		May		Jun		Jul		Aug		Sep		Oct		Nov		Dec
	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min
	----------------------------------------------------------------- oF ------------------------------------------------------------
Max.	34	33	38	36	50	46	60	56	70	65	74	70	79	72	76	72	73	68	62	57	52	50	38	36
Min.	31	30	30	28	36	35	45	41	52	49	60	54	69	64	71	63	61	57	47	46	37	31	32	29
2001 mean	32	31	33	31	44	41	50	46	61	56	68	62	74	68	74	68	67	62	53	51	45	43	35	33
10-yr mean	34	33	39	36	49	42	58	48	69	58	76	65	83	71	83	72	74	65	60	53	44	41	36	35
34-yr mean	33	32	38	34	50	41	61	48	73	58	81	66	89	74	87	73	76	64	61	51	44	39	34	33

Table 9. Last and first frost ([32°F) dates and number of frost-free days, Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2001.
 

Table 10. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, OR from 1943 through 2001.
 

Table 11. Annual snowfall totals at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2001.
 

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Malheur Agricultural Experiment Station

Last updated  Tuesday July 30, 2002 .