Malheur Experiment Station Information for Sustainable Agriculture

1998 Weather Report

Erik B. G. Feibert and Clinton C. Shock
Malheur Experiment Station
Oregon State University
Ontario, OR

Introduction

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-in 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 monitors air temperature, relative humidity, dew point temperature, precipitation, wind run, wind speed, wind direction, solar radiation, and soil temperature at 8-in and 20-in depths. Stored 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 may be accessed via computer modem through the Internet at: www.pn.usbr.gov/agrimet.

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.

Methods

The ground under and around the weather stations has been covered with turf grass since October 17, 1997. The grass is irrigated with subsurface drip irrigation. The ground around and under the weather stations before October 17, 1997, was bare. The weather data is recorded each day at 8:00 a.m. All data pertains to the preceding 24-hour period except the 8:00 a.m. air temperature.

Evaporation is measured from April through October as inches of water evaporated from a standard 10-in deep by 47.5-in diameter pan over 24 hours. Wind run is measured as total wind movement in miles over a 24 hour period measured at 24 inches above ground level. Weather data averages in the tables refer to the years preceding and up to, but not including the current year.

1998 Weather

The 1998 growing season started out cooler and wetter than normal. The month of May had 4.55 in of precipitation compared to the 55-year mean of 1.02 in (Table 1). May had 29 percent fewer and June had 18 percent fewer growing degree-days (50 -86 °F) than the previous 10 year mean (Table 2). Pan-evaporation for May totaled 5.9 in, 34 percent lower than the 10-year mean and 22 percent lower than the 48-year mean (Table 3).

A severe hail storm occurred on July 4 at 7:31 p.m. in an approximately 2-mile wide and 8-mile long zone running from about 3 miles west of the station through the center of Ontario at the level of Ontario High School. Major crop damage resulted from the hail. The rain gauge at the station recorded 0.93 in of precipitation for the half-hour duration of the hail storm. Actual precipitation could have been higher because hail tends to bounce out of the rain gauge.

The months of July and August were hotter than normal. Weather station data recorded 11 days with maximum air temperatures of 100 °F or higher compared to the 50-year mean of 5 days. There were far more degree-days in the above optimal range (86 to 104 °F) in 1998 compared to the previous 8-year mean; 70 percent more in July, 29 percent more in August, and 39 percent more for the whole year (Table 4).

Mean monthly maximum air temperatures were close to the 10-year and 53-year means (Table 5). The total accumulated growing degree days (50-86 °F) was close to the 10-year mean (Table 2).

The mean monthly maximum and minimum 4-in soil temperatures in January and February were higher than the 10-year and 31-year means (Table 6). From March through October the mean monthly maximum and minimum 4-in soil temperatures were lower than the 10-year and 31-year means. The difference in soil temperature between 1998 and the mean is probably caused by the installation of turf around the weather station in October of 1997. The soil remains warmer in winter and cooler in spring and summer under the turf compared to the bare ground in the past.

Total pan-evaporation for April through October was 51.4 inches, lower than the 10-year mean and close to the 48-year mean (Table 3).

The last spring frost ([32 °F) occurred on April 18, eight days earlier than the 20-year mean date of April 26; the first fall frost occurred on October 17, thirteen days later than normal (Table 7).

The monthly wind-run totals for the months of April through October were higher than the 50-year mean (Table 8).

The weather in 1998 did not exceed any record weather events recorded over the 54-year history for the Malheur Experiment Station except that May was the wettest month on record (Table 9). The highest temperature for the year was 105 °F on August 6 (Table 5). The lowest temperature for the year was -2 °F on December 23. Total precipitation was 15.28 in for the year, 51 percent higher than the 10-year station average and 49 percent higher than the 55-year station average (Table 1). Total snowfall for 1996 was 14.6 in, slightly lower than the 10-year and 54-year means, respectively (Table 10).

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

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
	----------------------------------------------------- inches -----------------------------------------------------
1988	1.25	0.14	0.26	0.75	0.50	0.65	0.06	0.00	0.04	0.00	2.45	1.48	7.58
1989	0.88	1.27	2.17	0.50	0.60	0.77	0.08	0.94	0.83	0.86	0.24	0.01	9.15
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
10-yr avg	1.31	0.65	0.96	1.09	1.17	0.85	0.37	0.28	0.25	0.73	1.27	1.21	10.14
55-yr avg	1.33	0.92	0.96	0.81	1.02	0.8	0.25	0.42	0.5	0.71	1.2	1.35	10.28

Table 2. Cumulative monthly growing degree-days (50-86 °F). Malheur Experiment Station, Oregon State University, Ontario, OR, 1988-1997.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
1988	0	5	56	236	554	1139	2050	2741	3117	3426	3446	3446
1989	0	0	13	197	469	1018	1751	2332	2721	2838	2852	2852
1990	2	9	88	327	588	1085	1819	2454	3039	3077	3077	3077
1991	0	13	29	153	365	754	1530	2248	2684	2878	2879	2879
1992	0	13	119	321	803	1377	2016	2720	3105	3279	3283	3283
1993	0	0	23	104	527	885	1349	1873	2281	2533	2539	2539
1994	0	2	94	283	652	1175	1969	2743	3252	3396	3398	3398
1995	0	29	61	167	460	893	1573	2161	2633	2734	2737	2747
1996	0	5	58	193	436	929	1687	2345	2709	2903	2921	2923
1997	4	4	85	202	621	1130	1791	2497	2977	3134	3154	3154
1998	0	2	54	166	400	805	1607	2356	2871	3022	3038	3042
10-yr avg	1	8	63	218	548	1034	1754	2411	2852	3020	3029	3030

Table 3. Pan-evaporation totals. Malheur Experiment Station, Oregon State University, Ontario, OR, 1998.

Totals	April	May	Jun	Jul	Aug	Sep	Oct	Total
Daily	------------------------------------------- inches --------------------------------------------
Mean	0.18	0.19	0.28	0.37	0.36	0.22	0.15
Max.	0.27	0.35	0.41	0.53	0.54	0.32	0.3
Min.	0.1	0	0.1	0.1	0.25	0.06	0.07
Annual	---------------------------------------------- inches ------------------------------------------
1998	5.12	5.91	8.27	9.9	11.21	6.5	4.52	51.43
10-yr avg	6.10	9.01	9.81	11.83	10.42	7.59	4.36	59.12
48-yr avg	5.54	7.60	8.80	11.10	9.50	6.19	3.09	51.15

Table 4. Monthly degree-days (86 -104 °F). Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-1998.

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
8-yr avg	0	2	8	37	35	6	0	88

Table 5. Monthly air temperature. Malheur Experiment Station, Oregon State University, Ontario, OR, 1998.

	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.	51	37	58	41	68	49	81	47	85	52	91	58	103	69	105	64	97	65	83	46	63	42	60	44
Min.	28	14	41	22	40	24	51	31	49	38	66	34	79	56	84	48	68	43	56	23	41	24	15	-2
1998 avg	41	29	48	32	55	34	62	38	68	46	78	48	95	61	93	57	84	52	66	36	52	36	37	22
10-yr avg	35	20	43	23	56	31	65	38	74	46	82	53	90	57	89	54	81	46	67	35	47	27	38	20
53-yr avg	35	19	43	25	55	31	64	37	74	45	82	52	91	57	90	55	80	46	65	36	48	28	37	22

Table 6. Monthly 4-in soil temperature. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1998.

	Jan		Feb		Mar		Apr		May		Jun		Jul		Aug		Sep		Oct		Nov		Dec
	High	low	High	low	High	low	High	low	High	low	High	low	High	low	High	low	High	low	High	low	High	low	High	low
	------------------------------------------------------ °F ------------------------------------------------
Max.	42	41	44	44	58	48	59	53	65	60	73	63	78	72	78	71	73	69	65	62	50	48	44	44
Min.	37	36	41	41	41	41	45	42	54	53	60	54	67	60	68	64	63	61	48	46	43	42	28	45
1998 mean	38	38	42	42	45	44	51	46	59	55	65	59	74	68	73	68	69	64	55	51	45	44	35	46
10-yr mean	33	32	39	35	51	42	62	50	73	59	81	67	89	74	87	74	78	66	63	53	45	40	35	47
31-yr mean	33	32	38	34	51	41	62	48	74	58	82	67	90	75	88	74	77	64	61	51	44	39	34	48

Table 7. Last and first frost ([32 °F) dates and number of frost-free days. Malheur Experiment Station, Oregon State University, Ontario, OR, 1976-1998.

Year	Date of last frost	Date of first frost	Total frost-free days
	Spring	Fall
1976	Apr 23	Oct 5	165
1977	Apr 20	Sep 22	155
1978	Apr 23	Oct 14	174
1979	Mar 20	Oct 27	221
1980	Apr 13	Oct 17	187
1981	Apr 14	Oct 1	170
1982	May 5	Oct 5	153
1983	Apr 27	Sep 20	146
1984	May 7	Sep 25	141
1985	May 13	Sep 30	140
1986	May 23	Oct 12	142
1987	Apr 21	Oct 11	173
1988	May 2	Oct 30	181
1989	May 19	Sep 13	117
1990	May 8	Oct 7	152
1991	Apr 30	Oct 4	157
1992	Apr 24	Sep 14	143
1993	Apr 20	Oct 11	174
1994	Apr 15	Oct 6	174
1995	Apr 16	Sep 22	159
1996	May 6	Sep 23	139
1997	May 3	Oct 8	158
1998	Apr 18	Oct 17	182
Average	April 26	October 4	161

Table 8. Daily wind-run totals and monthly totals. Malheur Experiment Station, Oregon State University, Ontario, OR, 1998.

Total	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Daily	-------------------------------------------- miles ------------------------------------------------
Max.	193	196	304	132	138	151	92	107	104	232	259	225
Min.	14	21	31	32	19	18	23	25	20	23	16	24
Average	55	83	85	74	61	63	52	56	45	69	72	74
Annual	---------------------------------------------- miles -------------------------------------------------
1998	1,704	2,332	2,634	2,226	1,890	1,902	1,619	1,722	1,350	2,136	2,169	2,279
10-yr average				2247	2369	1983	1774	1597	1562	1660
50-yr average				2110	1891	1531	1449	1291	1228	1252

Table 9. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, OR.

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 oF	Aug 4, 1961
Total days with max. air temp. m 100 °F	17 days	1971
Lowest air temperature	-26 °F	Jan 21 and 22, 1962
Total days with min. air temp. [ 0 °F	35 days	1985
Lowest 4-in soil temperature	12 °F	Dec 24, 25, and 26, 1990

Table 10. Annual snowfall totals at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1988-1997.

1988	1989	1990	1991	1992	1993	1994	1995	1996	1997	1998	10-yr avg	54-yr avg
--------------------------------------------- inches ---------------------------------------------
34.80	25.10	5.70	7.50	15.50	36.00	32.00	15.00	14.50	5.80	14.60	19.19	18.88

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Malheur Agricultural Experiment Station

Last updated  Tuesday July 30, 2002 .