This is the last article in a series that summarizes the simulated crop stages and yield forecasts across the Corn Belt. To evaluate, in “real-time,” the impact of this season’s weather on corn yield and its spatial variability across the Corn Belt, simulations of 2024 real-time crop stage were performed for 43 locations across the U.S. Corn Belt using the UNL Hybrid-Maize crop model; the data can be seen in Table 1. Details on the UNL Hybrid-Maize crop model and the underpinning methodology to simulate phenology and forecast end-of-season yields is described in a previous article.

Figure 1. Daily solar radiation, maximum and minimum air temperature (Tmax and Tmin), total rainfall, and total reference grass-based evapotranspiration (ET) for the time period between Aug. 28 and Sept. 16, 2024. Vertical bars indicate the range for these variables based on 20-plus years of weather records. The horizontal thick line indicates the long-term average and the red dots indicate the 2024 values. Table 1. Data from simulations of 2024 end-of-season corn yield potential and real-time crop stage performed on Sept. 16.

	Location	Water regime	Long-term average yield (bu/ac) §	Range of Yp forecasts as of Sep 16 (bu/ac)¶ 25th	Range of Yp forecasts as of Sep 16 (bu/ac)¶ 75th	Probability (%) of 2024 yield to be: Below (relative to the long-term Yp)†	Probability (%) of 2024 yield to be: Near (relative to the long-term Yp)†	Probability (%) of 2024 yield to be: Above (relative to the long-term Yp)†	Simulated current crop stage*
NE	Alliance	Irrigated	230	Black layer on Sept. 8. Final yield: 241 bu/ac					Matured
	Beatrice	Dryland	183	Black layer on Aug. 24. Final yield: 166 bu/ac					Matured
		Irrigated	241	Black layer on Aug. 26. Final yield: 237 bu/ac					Matured
	Clay Center	Dryland	186	Black layer on Sept. 8. Final yield: 232 bu/ac					Matured
		Irrigated	258	Black layer on Sept. 8. Final yield: 263 bu/ac					Matured
	Concord	Dryland	201	226	232	0%	0%	100%	R5, Dent
		Irrigated	268	279	285	0%	43%	57%	R5, Dent
	Elgin	Irrigated	268	Black layer on Sept. 15. Final yield: 260 bu/ac					Matured
	Holdrege	Dryland	143	Black layer on Sept. 3. Final yield: 159 bu/ac					Matured
		Irrigated	257	Black layer on Sept. 9. Final yield: 263 bu/ac					Matured
	McCook	Dryland	119	Black layer on Aug. 28. Final yield: 110 bu/ac					Matured
		Irrigated	238	Black layer on Aug. 31. Final yield: 239 bu/ac					Matured
	Mead	Dryland	206	Black layer on Sept. 4. Final yield: 241 bu/ac					Matured
		Irrigated	247	Black layer on Sept. 4. Final yield: 256 bu/ac					Matured
	North Platte	Dryland	131	Black layer on Sept. 9. Final yield: 100 bu/ac					Matured
		Irrigated	256	Black layer on Sept. 13. Final yield: 252 bu/ac					Matured
	O'Neill	Irrigated	247	Black layer on Sept 14. Final yield: 253 bu/ac					Matured
IA	Ames	Dryland	250	Black layer on Sept. 10. Final yield: 240 bu/ac					Matured
	Crawfordsville	Dryland	238	Black layer on Sept. 9. Final yield: 260 bu/ac					Matured
	Kanawha	Dryland	256	Black layer on Sept. 15. Final yield: 255 bu/ac					Matured
	Lewis	Dryland	221	Black layer on Sept. 6. Final yield: 226 bu/ac					Matured
	Nashua	Dryland	257	257	270	0%	97%	0%	R5, Dent
	Sutherland	Dryland	245	253	256	0%	100%	0%	R5, Dent
IL	Bondville	Dryland	252	Black layer on Sept. 11. Final yield: 277 bu/ac					Matured
	Freeport	Dryland	242	Black layer on Sept. 15. Final yield: 250 bu/ac					Matured
	Olney	Dryland	210	Black layer on Aug. 27. Final yield: 230 bu/ac					Matured
	Peoria	Dryland	228	Black layer on Sept. 10. Final yield: 273 bu/ac					Matured
	Springfield	Dryland	216	Black layer on Aug. 30. Final yield: 261 bu/ac					Matured
IN	Butlerville	Dryland	237	Black layer on Sept. 3. Final yield: 250 bu/ac					Matured
	Columbia City	Dryland	250	247	259	0%	100%	0%	R5, Dent
	Davis	Dryland	257	Black layer on Sept. 12. Final yield: 261 bu/ac					Matured
	West Lafayette	Dryland	254	Black layer on Sept. 6. Final yield: 270 bu/ac					Matured
KS	Garden City	Irrigated	237	Black layer on Aug. 19. Final yield: 225 bu/ac					Matured
	Hutchinson	Dryland	118	Black layer on July 30. Final yield: 82 bu/ac					Matured
	Manhattan	Dryland	158	Black layer on Aug. 13. Final yield: 188 bu/ac					Matured
	Scandia	Dryland	158	Black layer on Aug. 17. Final yield: 104 bu/ac					Matured
		Irrigated	234	Black layer on Aug. 26. Final yield: 247 bu/ac					Matured
	Silverlake	Dryland	162	Black layer on Aug. 13. Final yield: 186 bu/ac					Matured
		Irrigated	218	Black layer on Aug. 17. Final yield: 228 bu/ac					Matured
MI	Ceresco	Dryland	231	238	252	0%	74%	26%	R5, Dent
	East Lansing	Dryland	236	256	282	0%	36%	64%	R5, Dent
	Munger	Dryland	245	259	278	0%	47%	53%	R5, Dent
MN	Eldred	Dryland	162	196	216	0%	4%	96%	R5, Dent
	Lamberton	Dryland	245	261	264	0%	100%	0%	R5, Dent
	Waseca	Dryland	246	274	284	0%	16%	84%	R5, Dent
MO	Brunswick	Dryland	194	Black layer on Aug. 22. Final yield: 229 bu/ac					Matured
	Monroe City	Dryland	191	Black layer on Aug. 24. Final yield: 224 bu/ac					Matured
	St. Joseph	Dryland	187	Black layer on Aug. 21. Final yield: 236 bu/ac					Matured
ND	Dazey	Dryland	164	155	180	24%	48%	28%	R5, Dent
OH	Custar	Dryland	231	Black layer on Sept. 7. Final yield: 229 bu/ac					Matured
	South Charleston	Dryland	235	Black layer on Aug. 29. Final yield: 197 bu/ac					Matured
	Wooster	Dryland	236	261	275	0%	21%	79%	R5, Dent

§ Long-term (last 20-plus years) potential yield at each location and surrounding area.
¶ Range of forecasted 2024 potential yields based on average planting date in 2024, indicating the potential yields in the 25th and 75th percentile of the potential yield distribution (associated with respective adverse and favorable weather scenarios during the rest of the season).
† Probability of obtaining a 2024 yield below (10%) than the long-term potential yield at each location; or 5% at each irrigated location, respectively.

Crop Stages and Weather Conditions During the Last Three Weeks

Corn has reached black layer stage at most of the sites, except for those located in northern and north-eastern fringes of the region, including ND, MN, MI, and north of NE, IA, IN and eastern OH (Figure 2). During the late grain filling, daytime temperature was above-normal and nighttime temperature was near or below-normal, except for NE with above-average night temperatures. Rainfall was well below normal across the entire region, with most sites receiving little or no rain during the past three weeks. Rainfall was near normal only in the northernmost region (ND and northern MN) and a couple of locations in IA and KS. A summary of weather conditions during the past three weeks is shown in Figure 1.

Figure 2. Simulated developmental stage for irrigated and rainfed corn at each location. R4: dough; R5: dent; physiological maturity: Matured. Separate maps are shown for irrigated corn (top) and rainfed corn (bottom).

Near Average Yields in Irrigated Corn

Forecasted end-of-season irrigated yields are shown in Figure 3 and 4. Almost every irrigated site (11 out of 13) exhibited near-average yields. Although temperatures in NE have been above average over the past three weeks, yields remain consistent with our previous forecast and similar to the historical averages, while being higher than the previous (2023) season.

Rainfed Corn: Near-to-Above Average Yields Across Rainfed Sites

There is a high probability of near to above-average yields for most sites. Overall, 46% of the sites (18 out of 39) are projected to achieve near average yields, while 36% (14 out of 39) are expected to obtain above-average yields. Above-average yields are expected in sites located in MN, NE, KS, MO, IL and eastern OH (Figures 3 and 4). Only a few sites in western NE and KS and southern OH exhibited below-average yields.

Overall, the 2024 yield scenario is above the long-term average, which is in line with our previous report in late August. When compared with the 2023 season results, the current season's scenario is more optimistic in ND, MN, IA, IL and MO. Conversely, the forecasts are more pessimistic in OH compared with last season, while KS, NE and IN are expected to have fairly similar yields overall. 

Figure 3. Vertical lines indicate the range of forecasted 2024 corn yield potential by Sept. 17 based on average 2024 planting date at each location. Horizontal lines indicate the 25th and 75th percentiles of the yield distribution (associated with respective adverse and favorable weather scenarios during the rest of the season). The blue squares indicate the long-term (2005-2023) average yield potential at each location and the red dots represent the forecasted 2024 corn yield potential at sites that have already reached maturity. Separate charts are shown for irrigated corn (top) and rainfed corn (bottom).

Figure 4. Probability of the 2024 yield potential to be below (at least 10% below for rainfed sites or 5% for irrigated sites, red color), near (±10% for rainfed sites or ±5% for irrigated sites, yellow color), and above (at least 10% above for rainfed sites or 5% above for irrigated sites, green color) the long-term (2005-2023) average yield potential at each location. Separate maps are shown for irrigated corn (top) and rainfed corn (bottom). The larger a color section is within the pie chart, the higher the probability that end-of-season corn yield will be in that category.

Conclusions

Aggregated at regional level, our forecasted yield potential this season is 6% above the historical yield trend. In line with USDA predictions (view USDA charts here), our forecast foresees higher average corn yield compared to that from last year. Our forecast suggests a near average year for a majority of irrigated sites.

For rainfed corn, most sites (>80%) expect near or above average yields, except for a few sites in western NE and KS and southern OH, where there is a high probability of below-average yields.

Note that these forecasts do not take into consideration problems with stand emergence, hail/flooding damage, replanting situations, disease or nitrate leaching. In fields negatively affected by these constraints, actual yields will be lower than estimates provided here.

It is important to keep in mind that yield forecasts are not field specific and, instead, represent an estimate of average on-farm yield for a given location and surrounding area in absence of the yield-reducing factors mentioned here. Likewise, crop stages and forecasted yields will deviate from those reported here in fields with planting dates or hybrid maturities that differ markedly from those used as the basis for these forecasts.