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 on 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 turf grass 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 assuming full cover for the whole season. Alfalfa peak Et is calculated assuming that the alfalfa is kept uncut during the season. Alfalfa mean Et is calculated 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 year started wetter than normal, but the spring and summer were drier than normal. The total precipitation from January through March was 57 and 58 percent higher than the 10-year and 55-year averages, respectively (Table 1). The total precipitation from April through August was 1.35 inch, which was 68 and 60 percent lower than the 10-year and 55-year averages, respectively. The total precipitation for 2000 was close to the 10-year and 55-year averages.

The months of April through August had a higher number of growing degree days (50 to 86°F) than normal (Table 2). The months of September through December had a lower number of growing degree-days (50 to 86°F) than normal. The total number of growing degree-days in 2000 was close to the 10-year and 14-year averages (Table 2). The total number of growing degree-days in 2000 was close to the 10-year average. Since 1990, the year 1994 had the highest total growing degree-days and 1993 had the lowest total growing degree-days (Fig. 1). July and August combined had 17 percent more degree days in the above optimal range (86 to 104°F) than the previous 10-year average (Table 3). There were nine percent more total degree-days in the above optimal range in 2000 than the previous 10-year average.

The months of May through September had total wind runs higher than the 9-year average (Table 4). Total pan-evaporation for June through August was 13 percent higher than the 10-year average and 20 percent higher than the 50-year average (Table 5). Total pan-evaporation for 2000 was higher than the 10-year and 55-year averages.

Total Et for all crops in 2000 was higher than the 8-year mean (Table 6). Total Et for alfalfa, sugar beet, onion, potatoes, and field corn in 2000 was the highest since 1992. Reference Et in 2000 was also the highest since 1993.

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 four-inch soil temperatures were lower than the 10-year and 33-year average (Table 8). The difference in soil temperature between 2000 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 May 12, 15 days later than the 24-year average date of April 27; the first fall frost occurred on September 24, 11 days earlier than normal (Table 9).

The weather in 2000 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 102°F on August 2 (Table 6). The lowest temperature for the year was 8°F on January 6. Total precipitation was 9.64-inches for the year, slightly lower than the 10-year station average and the 55-year station average (Table 1). Total pan-evaporation for April through October was 60.8 inches, slightly higher than the 10-year and 52-year average (Table 4). Total snowfall for 2000 was 13.8 inches, lower than the 10-year and 57-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, 1990-2000.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
	----------------------------------------- inches -----------------------------------------------
1990	0.44	0.35	0.72	1.52	1.70	0.36	0.04	0.61	0.00	0.49	0.69	0.29	7.21
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
10-yr avg	1.48	0.90	0.87	1.13	1.54	0.85	0.47	0.20	0.27	0.69	1.15	1.25	10.80
55-yr avg	1.35	0.96	0.95	0.81	1.08	0.80	0.26	0.41	0.50	0.69	1.19	1.33	10.33

Figure 1. Cumulative growing degree-days (50 to 86°F) for selected years, Malheur Experiment Station, Oregon State University, Ontario, OR, 2000.

Table 2. Monthly total growing degree-days (50-86°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2000.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
1990	2	7	79	239	261	497	734	635	585	38	0	0	3,077
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
14-year avg	1	7	58	138	310	476	704	676	457	159	10	2	3,049

Table 3. Monthly total degree-days (86 -104°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2000.

Year	Apr	May	Jun	Jul	Aug	Sep	Oct	Total
1990	0	0	13	56	41	14	0	124
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
10-yr avg	0	2	7	38	34	6	0	87

Table 4. Daily wind-run totals and monthly totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2000.

Daily	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	------------------------------------ miles-------------------------------------------
Max.	113	235	138	196	218	157	110	122	182	169	119	114
Min.	16	17	25	38	30	33	29	32	21	11	7	9
Average	43	70	75	81	83	75	68	66	66	49	39	37
Annual total	-------------------------------------- miles ----------------------------------------------
2000	1,326	2,032	2,329	2,422	2,565	2,244	2,099	2,051	1,979	1,513	1,158	1,159
9-yr average	1,603	1,752	2,384	2,487	2,315	1,959	1,774	1,665	1,602	1,830	1,644	1,740
52-yr average				2,138	1,912	1,547	1,461	1,311	1,243	1,279

Table 5. Pan-evaporation totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2000.

Totals	Apr	May	Jun	Jul	Aug	Sep	Oct	Total
Daily	-------------------------------------- inches ---------------------------------------
Mean	0.22	0.28	0.35	0.41	0.39	0.23	0.11	1.99
Max.	0.38	0.5	0.53	0.56	0.58	0.4	0.24	3.19
Min.	0.1	0.13	0.09	0.11	0.25	0.1	0.01	0.79
Annual	---------------------------------------- inches ------------------------------------
2000	6.42	8.68	10.64	12.68	11.95	6.95	3.44	60.76
10-yr avg	6.10	8.78	9.31	11.41	10.40	7.70	4.43	58.13
52-yr avg	5.57	7.62	8.82	11.09	9.56	6.26	3.19	52.11

Table 6. Total Et (acre-inches/acre), Malheur Experiment Station, Oregon State University, Ontario, OR, 1992-2000.

Year	Reference Et	Alfalfa (peak)	Alfalfa (mean)	Spring grain	Sugar beet	Onion	Potato - Shepody	Potato	Field corn
1992	na	51.8	44.5	28.6	34.8	30.6	32.6	27.6	29.2
1993	44.0	42.5	36.7	22.4	29.5	24.2	22.4	22.9	24.5
1994	49.9	47.4	40.7	23.2	34.5	29.6	22.5	28.0	28.6
1995	44.7	43.4	37.2	23.1	29.0	25.6	24.7	24.1	24.3
1996	47.5	46.4	39.8	23.7	33.0	28.0	25.1	27.1	26.7
1997	49.6	48.3	41.6	25.8	33.4	28.0	24.7	28.3	26.2
1998	48.9	47.4	40.6	24.6	32.5	28.2	25.1	27.1	27.9
1999	53.0	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
8-year avg		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, 2000.

	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
	-------------------------------------------------------°F ---------------------------------------------------------
Max.	54	34	59	40	68	40	83	50	89	57	94	59	101	71	102	65	94	62	85	65	57	37	46	36
Min.	25	8	39	23	45	26	61	31	55	31	67	39	77	47	81	47	64	30	51	30	28	15	29	19
2000 avg	38	26	49	33	55	32	69	41	74	47	83	52	92	59	93	56	77	46	64	40	42	26	36	26
10-yr avg	38	23	45	26	57	32	64	37	73	46	80	51	90	57	90	54	82	47	66	35	48	28	37	21
53-yr avg	35	20	43	25	55	31	64	37	73	45	82	52	91	57	90	55	80	46	66	36	48	28	37	22

Table 8. Monthly 4-inch soil temperature, Malheur Experiment Station, Oregon State University, Ontario, OR, 2000.

	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
	------------------------------------------------------------°F ------------------------------------------------------
Max.	37	35	42	40	49	45	62	53	67	62	74	68	79	72	77	72	69	65	61	59	47	46	37	36
Min.	31	29	33	32	40	38	48	43	54	49	61	57	66	61	70	65	59	54	49	47	34	34	32	31
2000 mean	33	32	38	37	44	41	55	50	61	56	68	62	73	67	73	68	64	60	55	52	40	39	34	34
10-yr mean	34	33	39	35	50	42	60	49	70	58	78	65	85	72	84	73	76	66	60	53	45	41	35	34
33-yr mean	33	32	38	34	50	41	61	48	73	58	82	67	89	74	88	73	77	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, 1990-2000.

Table 10. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, OR, from 1943 through 2000.

Record event	Measurement	Date
Greatest annual precipitation	16.87 in	1983
Greatest monthly precipitation	4.55 in	May 1998
Greatest 24-hour precipitation	1.52 in	Sep 14, 1959
Greatest annual snowfall	40 in	1955
Greatest 24-hour snowfall	10 in	Nov 30, 1975
Earliest snowfall	1 in	Oct 25, 1970
Highest air temperature	108°F	Aug 4, 1961
Total days with maximum air temp. m100°F	17 days	1971
Lowest air temperature	-26°F	Jan 21 and 22, 1962
Total days with minimum air temp. [0°F	35 days	1985
Lowest 4-in soil temperature	12°F	Dec 24, 25, and 26, 1990

Table 11. Annual snowfall totals at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2000.

1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	10-yr avg	57-yr avg
----------------------------------------------- inches -----------------------------------------------
5.7	7.5	15.5	36.0	32.0	15.0	14.5	5.8	14.6	13.2	13.8	16.0	18.7

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Malheur Agricultural Experiment Station

Last updated  Tuesday July 30, 2002 .