Malheur Experiment Station Information for Sustainable Agriculture

2004 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-inch depth was added in 1967. A biophenometer, to monitor degree days, and pyranometers, to monitor total 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.

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.

On June 1, 1992, in cooperation with the U.S. Department of the Interior, Bureau of Reclamation, a fully automated weather station, linked 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 are transmitted via satellite to the Boise computer every 4 hours and are used to calculate daily Malheur County crop water-use estimates. The AgriMet database can be accessed through the internet at www.usbr.gov/pn/agrimet and is linked to the Malheur Experiment Station web page at www.cropinfo.net.

Methods

The ground under and around the weather stations was bare until October 17, 1997, when it was covered with turfgrass. The grass is irrigated with subsurface drip irrigation. The weather data are recorded each day at 8:00 a.m. Consequently, the data in the tables of daily observations refer to the previous 24 hours.

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_c) for each crop is calculated by the AgriMet computer using data from the AgriMet weather station and the Kimberly-Penman equation (Wright 1982). Reference evapotranspiration (ET₀) is calculated for a theoretical 12- to 20-inch-tall crop of alfalfa assuming full cover for the whole season. Evapotranspiration for all crops is calculated using ET₀ and crop coefficients for each crop. These crop coefficients vary throughout the growing season based on the plant growth stage. The crop coefficients are tied to the plant growth stage by three dates: start, full cover, and termination dates. Start dates are the beginning of vegetative growth in the spring for perennial crops or the emergence date for row crops. Full cover dates are typically when plants reach full foliage. Termination dates are defined by harvest, frost, or dormancy. Alfalfa mean ET_c is calculated for an alfalfa crop assuming a 15 percent reduction to account for cuttings.

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.

2004 Weather

The total precipitation for 2004 (11.98 inches) was higher than the 10-year (10.19 inches) and 60-year (10.16 inches) averages (Table 1). Precipitation in October was about three times the 10-year and 60-year averages. Total snowfall for 2004 (24 inches) was higher than the 10-year (14.0 inches) and 61-year averages (18.2 inches) (Table 2).

The highest temperature for 2004 was 104°F on July 18 (Table 3). The lowest temperature for the year was -1°F on January 5. The average maximum and minimum air temperatures for March were substantially higher than the 10-year and 60-year averages. March 31 reached 80°F.

March had the highest number of growing degree days (50° to 86°F) for that month since 1986, when measurements were started (Table 4, Fig. 1). The total number of degree days in the above-optimal range in 2004 was close to the average (Table 5).

The months of May through December had total wind runs lower than the 10-year average (Table 6). Total pan-evaporation for 2004 was close to the 10-year and 56-year averages (Table 7). Total accumulated ET_c for all crops in 2004 was close to the 10-year average (Table 8).

The average monthly maximum and minimum 4-inch soil temperatures in 2004 were close to the 10-year and 37-year averages (Table 9).

The last spring frost ([32°F) occurred on April 16, 13 days earlier than the 28-year average date of April 29; the first fall frost occurred on October 24, 19 days later than the 28-year average date of October 5 (Table 10). The 191 frost-free days was the longest frost-free period over the last 14 years.

No other weather records were broken in 2004 (Table 11).

References

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, 1991-2004.

Table 2. Annual snowfall totals at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2004.

1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001	2002	2003	2004	10-yr avg	61-yr avg
----------------------------------------------------------------- inches -----------------------------------------------------------------
7.5	15.5	36.0	32.0	15.0	14.5	5.8	14.6	13.2	13.8	15.5	11.5	4.5	24.0	14.0	18.2

Table 3. Monthly air temperature, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

	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 ------------------------------------------------------------------
Highest	44	33	51	34	80	44	79	49	85	56	99	63	104	72	100	69	95	58	80	57	56	43	52	41
Lowest	13	-1	29	11	43	25	52	32	56	37	70	46	80	49	69	46	63	38	47	29	37	19	30	18
2004 avg	31	20	38	24	62	36	67	41	72	47	84	53	93	60	89	58	78	48	67	41	46	31	41	28
10-yr avg	38	25	46	27	56	32	64	37	72	45	81	51	93	59	91	55	81	47	66	36	48	29	38	24
60-yr avg	35	20	43	25	55	31	64	37	73	45	82	52	92	58	90	56	80	46	66	36	48	28	37	22

Figure 1. Cumulative growing degree days (50-86°F) over time for selected years compared to 14-year average, Malheur Experiment Station, Oregon State University, Ontario, OR.

Table 4. Monthly total growing degree days (50-86°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2004.

Table 5. Monthly total degree days in the above-ideal (86 -104°F) range, Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2004.

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
2002	0	0	14	54	11	5	0	85
2003	0	5	9	74	36	5	0	130
2004	0	0	18	43	31	2	0	94
14-yr avg	0	2	7	41	34	6	0	90

Table 6. Wind-run daily totals and monthly totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Daily	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	------------------------------------------- miles -----------------------------------------------
Mean	54	74	67	75	43	45	35	34	46	31	32	24
Max.	170	201	175	164	118	120	90	64	137	124	136	120
Min.	17	25	15	16	16	13	0	14	19	5	2	0
Annual total	-------------------------------------------- miles ------------------------------------------------
2004	1,659	2,143	2,092	2,261	1,320	1,336	1,087	1,039	1,389	972	947	739
10-yr average	1,573	1,942	2,500	2,512	2,293	1,932	1,723	1,685	1,554	1,798	1,616	1,912
56-yr average				2,150	1,937	1,572	1,477	1,332	1,253	1,290

Table 7. Pan-evaporation totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Totals	April	May	Jun	Jul	Aug	Sep	Oct	Total
Daily	-------------------------------------- inches ---------------------------------------
Mean	0.25	0.24	0.36	0.39	0.30	0.22	0.13
Max.	0.41	0.35	0.48	0.57	0.42	0.45	0.28
Min.	0.10	0.12	0.23	0.12	0.07	0.08	0.00
Annual	---------------------------------------- inches ------------------------------------
2004	7.25	7.51	10.66	12.09	9.23	6.55	3.82	57.11
10-yr avg	6.05	8.45	9.75	11.61	10.70	7.38	4.43	58.27
56-yr avg	5.61	7.72	8.94	11.15	9.64	6.32	3.28	51.78

Table 8. Total accumulated reference evapotranspiration (ET₀) and crop evapotranspiration (ET_c) (acre-inches/acre), Malheur Experiment Station, Oregon State University, Ontario, OR, 1992-2004.

Table 9. Monthly soil temperature at 4-inch depth, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

	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 ----------------------------------------------------------------
Highest	37	34	38	34	52	47	59	52	65	60	77	69	81	72	81	71	72	66	64	59	46	45	46	45
Lowest	31	30	32	29	37	36	47	43	55	50	61	56	69	63	66	62	59	55	48	45	34	33	32	32
2004 avg	33	32	33	32	45	41	54	48	61	55	70	62	76	68	74	68	65	60	56	52	42	40	37	36
10-yr avg	35	34	38	35	46	41	55	47	65	56	73	64	80	70	78	70	70	63	57	52	44	41	36	35
37-yr avg	33	32	38	34	49	40	59	47	71	57	80	66	87	73	85	72	75	63	59	51	44	40	35	33

Table 10. Last and first frost ([32°F) dates and number of frost-free days, Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2004.

Year	Date of last frost	Date of first frost	Total frost-free days
	Spring	Fall
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	140
1997	May 3	Oct 8	158
1998	Apr 18	Oct 17	182
1999	May 11	Sep 28	140
2000	May 12	Sep 24	135
2001	Apr 29	Oct 10	164
2002	May 8	Oct 12	157
2003	May 19	Oct 11	145
2004	April 16	Oct 24	191
1976-2003 Avg	April 29	October 5	159

Table 11. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, OR.

Home

Crops

Weather

Potato Blight

Water Quality

Irrigation

Weeds

Search

MES Publications, MES Notice of events, Vegetation,Malheur County, Leslie Gulch,Succor Creek,Owyhee River,Local wildlife,Strawberry Mountain, Eagle Caps

Malheur Agricultural Experiment Station

Last updated  Monday August 1, 2005 .