June 20, 2002

Rains in Iran End One Month Early

The rainy season in Iran came to an early end, with most growing regions receiving little rain for the past month (seasonal rainfall analysis).  The northwestern rainfed region, such as Lorestan and Kordestan (production maps), were particularly hard hit because wheat was at the critical flowering-heading stages when surface and sub-soil moisture (soil moisture map) deteriorated (wheat stage on May 28).  Significant rainfall is not expected in next month as seasonable dry conditions range from July to September.

Current winter wheat development in Iran ranges from flowering to maturity in the northwestern areas.  The harvest is nearly 80 percent complete in the southern areas of Fars and Khuzestan (Figure 1).  Harvesting of the wheat crop began in mid-April for the southern and eastern lowland areas (wheat stage in April), where the wheat crop is predominately irrigated and grows faster due to relatively warmer temperatures (harvest maps). The harvest of winter wheat in northwestern rainfed regions typically begins in mid-June and ends in August (provincial crop calendars).

Figure 1.  Estimated Wheat Stage in Iran on June 17, 2002

Summary of Season and 2002/03 Wheat Production Forecast

In general, the 2001/02 crop season was on a road to recovery from three consecutive years (1999-2001) of devastating drought, with seasonal rainfall totals near average in most regions from October to December (seasonal rainfall analysis).  Seasonal rainfall totals later dipped below normal from January to mid-March, but crop prospects dramatically improved when rains returned to normal from mid-March to April. A final good month of rainfall in May would have greatly helped the final stage of the wheat crop, especially in the rainfed northwest, but the rainy season ended one month early with all growing regions receiving very little rainfall from mid-May to mid-June.   

The rainfed northwestern region received rainfall totals ranging less than 50 to 75 percent of average, but rainfall patterns were favorable from Tehran and extending to the irrigated wheat region in southwestern Iran (percent of average precipitation map).  Despite seasonal rainfall totals being below average, the precipitation totals for 2001/02 growing season did surpass the rainfall totals from each of the previous three years of drought.  For example, vegetation vigor this year greatly exceeds the three-year drought average as shown in Figure 2.

Iran’s 2002/03 wheat production is tentatively forecasted at 9.5 million metric tons, slightly above the five-year average of 9.1 million and much above last year’s poor harvest of 7.5 million.   Both rainfall and vegetation analyses indicate better yields than the past three drought years.  In addition, vegetation vigor data derived from  SPOT-VEG and NOAA-AVHRR-16 satellite sensors indicate that the rainfall data reported to the World Meteorological Organization (WMO) may be misleading or missing several crucial days of rainfall reports.

Figure 2. Vegetation Vigor (June 1-10, 2002) Compared to the
Past Three Drought Years (Average NDVI for 1999-2001)

Other Recent Links about Iran from PECAD

Crop Explorer:  Actual weather  over major crop regions compared to long-term normal conditions
Iran's April 10 Update: "Rains Raise Winter Crop Prospects, but More Moisture Needed"
Iran's November 21 Update: "Iran's Wheat Crop Needs More Rain"

For more information, contact Curt Reynolds
with the Production Estimates and Crop Assessment Division, via e-mail Curt.Reynolds@fas.usda.gov or telephone (202) 690-0134.