This article summarizes the simulated crop stages and yield forecasts performed on Aug. 27 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 underpinning methodology to simulate phenology and forecast end-of-season yields, as well as on interpretation and uses of yield forecasts, are described in a previous article.

Cool weather prevailed over the past three weeks throughout the entire Corn Belt, together with cloudy days in the western fringe of the region. Additionally, 60% of the sites exhibited below-average rainfall, while a few scattered sites in NE, IN and MO received rainfall amounts that exceeded the historical average. A summary of weather conditions during the last three weeks is shown in Figure 1.

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. 5 and Aug. 26, 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 Aug. 27.

	Location	Water regime	Long-term average yield (bu/ac) §	Range of Yp forecasts as of Aug 27 (bu/ac)¶ 25th	Range of Yp forecasts as of Aug 27 (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	230	247	0%	60%	40%	R5, Dent
	Beatrice	Dryland	183	Black layer on Aug. 22. Final yield: 156 bu/ac					Matured
		Irrigated	241	242	244	0%	100%	0%	R5, Dent
	Clay Center	Dryland	186	221	233	0%	0%	100%	R5, Dent
		Irrigated	258	253	26	2%	82%	15%	R5, Dent
	Concord	Dryland	201	222	247	0%	24%	76%	R5, Dent
		Irrigated	268	273	293	0%	50%	50%	R5, Dent
	Elgin	Irrigated	268	255	272	31%	53%	17%	R5, Dent
	Holdrege	Dryland	143	156	162	0%	33%	67%	R5, Dent
		Irrigated	257	252	266	8%	75%	17%	R5, Dent
	McCook	Dryland	119	107	108	71%	29%	0%	R5, Dent
		Irrigated	238	228	235	19%	81%	0%	R5, Dent
	Mead	Dryland	206	239	247	0%	0%	100%	R5, Dent
		Irrigated	247	255	264	0%	50%	50%	R5, Dent
	North Platte	Dryland	131	86	92	100%	0%	0%	R5, Dent
		Irrigated	256	244	272	24%	45%	31%	R5, Dent
	O'Neill	Irrigated	247	243	265	13%	54%	33%	R5, Dent
IA	Ames	Dryland	250	229	244	14%	86%	0%	R5, Dent
	Crawfordsville	Dryland	238	249	261	0%	76%	24%	R5, Dent
	Kanawha	Dryland	256	249	265	0%	96%	4%	R5, Dent
	Lewis	Dryland	221	218	228	0%	96%	4%	R5, Dent
	Nashua	Dryland	257	258	275	0%	86%	14%	R4, Dough
	Sutherland	Dryland	245	245	271	0%	69%	31%	R5, Dent
IL	Bondville	Dryland	252	264	280	0%	66%	34%	R5, Dent
	Freeport	Dryland	242	245	263	0%	88%	12%	R5, Dent
	Olney	Dryland	210	232	236	0%	26%	74%	R5, Dent
	Peoria	Dryland	228	261	275	0%	3%	97%	R5, Dent
	Springfield	Dryland	216	261	267	0%	0%	100%	R5, Dent
IN	Butlerville	Dryland	237	249	256	0%	90%	10%	R5, Dent
	Columbia City	Dryland	250	259	283	0%	57%	43%	R4, Dough
	Davis	Dryland	257	262	272	0%	95%	5%	R5, Dent
	West Lafayette	Dryland	254	268	274	0%	86%	14%	R5, Dent
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	241	241	0%	100%	0%	R6, Black layer
	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	239	253	0%	74%	26%	R4, Dough
	East Lansing	Dryland	236	254	274	0%	39%	61%	R4, Dough
	Munger	Dryland	245	257	279	0%	53%	47%	R4, Dough
MN	Eldred	Dryland	162	175	201	4%	25%	71%	R4, Dough
	Lamberton	Dryland	245	254	269	0%	81%	19%	R5, Dent
	Waseca	Dryland	246	264	285	0%	43%	57%	R4, Dough
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	139	172	28%	62%	10%	R4, Dough
OH	Custar	Dryland	231	223	233	0%	100%	0%	R5, Dent
	South Charleston	Dryland	235	205	214	62%	38%	0%	R5, Dent
	Wooster	Dryland	236	255	275	0%	38%	62%	R4, Dough

§ 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.

Simulated Corn Stage Across 43 Locations

Corn has reached maturity in the southern fringe of the Corn Belt (KS and MO). In the rest of the region, corn has reached dent stage, except for a few sites in the northern and eastern region where corn is still in dough stage. In general, corn development is ahead relative to the 2023 crop season, except for ND, MN and IA, where development is similar to last year (Figure 2).

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).

Irrigated Corn: Near Average Yields Are Expected

The forecasted range of irrigated corn yield potential for each location, along with the probabilities for yields above, near, or below average, are shown in Figures 3 and 4. Half of the sites show a high probability (>75%, that is, three out of four chances) of near-average yield potential. This is also likely for the rest of the sites, except for one site in southwestern KS, where below-average yield are expected, and in eastern NE, where there is still a relatively high probability of above-average yield. At this point, the forecasted scenario for irrigated maize in the current season appears to be similar to that of 2023.

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

Although forecasted yield potential is variable across the 39 rainfed sites (Figures 3 and 4), there is a high probability of near to above-average yields for most sites. Overall, 11 sites across NE, KS, MO and IL show a high probability (>75%) of above-average yields, and there is a high probability of near average yields in 12 sites distributed in the central and eastern regions (IA, southern MN, northern IL, IN, OH and MI). Conversely, below-average yields are only likely in western NE and KS.

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 Aug. 27 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

Corn has already reached the dough stage across the Corn Belt, while dent stage (or even black-layer) has been attained in the southern fringe of the region. Similar results are expected compared to our previous forecasts: there is a high probability of near-average yields in irrigated sites. For rainfed corn, yields are expected to be near or above-average, except for a few sites in western NE and KS, where there is a high probability of below-average yields.

Overall, regional average yield this season is expected to be above the historical yield trend (+6% yield deviation), which is consistent with USDA-NASS prediction of above-average yields.

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.

We will follow up with the final forecasted yield and analysis of the 2024 crop season in September.