Simulations of 2024 end-of-season corn yield potential and real-time crop stage were performed on July 23 for 43 locations across the U.S. Corn Belt using the UNL Hybrid-Maize crop model in collaboration with faculty and extension educators from 10 universities. This article summarizes the simulated crop stages and yield forecasts; the data can be viewed in Table 1. Details on the UNL Hybrid-Maize crop model and 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.

A summary of weather conditions during the last 60 days (from May 23 to July 22) is shown in Figure 1. The season began with near-average temperatures in the central Corn Belt, while daytime temperatures were below normal in the northwestern fringe of the region (ND and MN). Total rainfall was near the historical average at most sites. However, consistent with drought monitor reports, rainfall was below average in western NE and parts of KS and OH, and above average in southern MN, northern IA and eastern NE.

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 May 23 and July 22, 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 for the same period.

Table 1. Data from simulations of 2024 end-of-season corn yield potential and real-time crop stage performed on July 23.

	Location	Water regime	Long-term average yield (bu/ac) §	Range of Yp forecasts as of Jul 23 (bu/ac)¶ 25th	Range of Yp forecasts as of Jul 23 (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	233	268	3%	37%	60%	R2, Blister
	Beatrice	Dryland	183	170	205	18%	50%	32%	R3, Milk
		Irrigated	241	234	259	15%	50%	35%	R3, Milk
	Clay Center	Dryland	186	214	240	0%	7%	93%	R2, Blister
		Irrigated	258	241	267	33%	43%	24%	R2, Blister
	Concord	Dryland	201	199	260	12%	29%	60%	R2, Blister
		Irrigated	268	253	290	29%	33%	38%	R2, Blister
	Elgin	Irrigated	268	239	279	47%	36%	17%	R2, Blister
	Holdrege	Dryland	143	146	161	0%	69%	31%	R3, Milk
		Irrigated	257	234	260	47%	33%	19%	R2, Blister
	McCook	Dryland	119	75	114	67%	24%	10%	R3, Milk
		Irrigated	238	217	245	45%	36%	19%	R3, Milk
	Mead	Dryland	206	226	248	0%	31%	69%	R3, Milk
		Irrigated	247	244	264	17%	50%	33%	R3, Milk
	North Platte	Dryland	131	75	122	71%	14%	14%	R2, Blister
		Irrigated	256	238	291	29%	24%	48%	R2, Blister
	O'Neill	Irrigated	247	235	268	26%	36%	38%	R2, Blister
IA	Ames	Dryland	248	210	249	36%	50%	14%	R2, Blister
	Crawfordsville	Dryland	238	239	257	3%	79%	18%	R3, Milk
	Kanawha	Dryland	256	249	268	0%	88%	12%	R2, Blister
	Lewis	Dryland	221	231	265	12%	19%	69%	R2, Blister
	Nashua	Dryland	257	254	279	6%	77%	17%	R1, Silking
	Sutherland	Dryland	245	244	269	6%	69%	26%	R2, Blister
IL	Bondville	Dryland	252	249	275	0%	81%	19%	R3, Milk
	Freeport	Dryland	242	233	261	3%	76%	21%	R2, Blister
	Olney	Dryland	210	209	237	9%	53%	38%	R3, Milk
	Peoria	Dryland	228	225	255	0%	65%	35%	R3, Milk
	Springfield	Dryland	216	196	240	25%	42%	33%	R3, Milk
IN	Butlerville	Dryland	237	216	251	14%	71%	14%	R3, Milk
	Columbia City	Dryland	250	258	287	0%	43%	57%	R1, Silking
	Davis	Dryland	257	253	266	5%	90%	5%	R2, Blister
	West Lafayette	Dryland	254	251	265	5%	76%	19%	R3, Milk
KS	Garden City	Irrigated	237	214	240	53%	42%	5%	R4, Dough
	Hutchinson	Dryland	118	81	91	100%	0%	0%	R5, Dent
	Manhattan	Dryland	158	175	194	0%	23%	77%	R4, Dough
	Scandia	Dryland	158	127	166	50%	39%	11%	R4, Dough
		Irrigated	234	221	247	29%	45%	26%	R3, Milk
	Silverlake	Dryland	162	175	188	0%	42%	58%	R4, Dough
		Irrigated	218	210	229	18%	47%	34%	R4, Dough
MI	Ceresco	Dryland	231	239	266	0%	43%	57%	R1, Silking
	East Lansing	Dryland	236	238	264	0%	61%	39%	R1, Silking
	Munger	Dryland	245	241	276	0%	58%	42%	R1, Silking
MN	Eldred	Dryland	162	145	179	29%	46%	25%	V10
	Lamberton	Dryland	245	254	272	0%	67%	33%	R2, Blister
	Waseca	Dryland	246	250	279	2%	57%	41%	R1, Silking
MO	Brunswick	Dryland	194	210	227	0%	33%	67%	R4, Dough
	Monroe City	Dryland	191	180	227	17%	30%	52%	R4, Dough
	St. Joseph	Dryland	187	216	236	0%	4%	96%	R4, Dough
ND	Dazey	Dryland	164	139	174	41%	41%	17%	V8
OH	Custar	Dryland	231	218	239	15%	74%	10%	R3, Milk
	South Charleston	Dryland	235	192	231	53%	44%	3%	R3, Milk
	Wooster	Dryland	236	236	264	5%	59%	36%	R1, Silking

§ 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 the silking stage at all sites except for the northwestern fringe of the region (ND and northern MN), where it is still in vegetative phases (Figure 2). Additionally, most sites in the southern part of the Corn Belt have reached the milk stage (central and southern IL, southern NE, and western and southern IN and OH) or even the dough stage (KS and MO).

Figure 2. Simulated developmental stage for irrigated and rainfed corn at each location. Vn: vegetative stage (nth leaf); R1: silking; R2: blister; R3: milk; R4: dough; R5: dent. Separate maps are shown for irrigated corn (top) and rainfed corn (bottom).

Irrigated Corn: High Probability of Near-average Yields

The range of forecasted irrigated corn yield potential for each location, as well as the probabilities for yields above, near, or below average, are shown in Figures 3 and 4. Although it is still early in the season, there is a relatively high probability of near-average yields for most irrigated sites, with above-average yields more likely in western NE. Weather conditions during the grain filling will ultimately determine if most irrigated sites achieve near-average yields.

Variation in 2024 Forecasted Rainfed Corn Yield

Forecasted yield potential is variable across rainfed sites (Figures 3 and 4). Overall, at this point of the season, the probability of near-average yields is relatively high in the northern, central, and eastern fringe of the Corn Belt (ND, MN, IA, IL, IN, MI and OH). Indeed, there is a high probability of near-average yields (>75%) in eight sites, which is consistent with USDA NASS crop reports.

Conversely, the probability of above-average yields increases towards the west and southwest of the Corn Belt (southwestern IA, southern and eastern NE, eastern KS, and MO). Finally, the western fringe of the region (western NE and southern KS) exhibits a high probability of below-average yields. Whether these trends persist will depend on precipitation and temperature patterns during the rest of July and early August.

Figure 3. Vertical lines indicate the range of forecasted 2024 corn yield potential by July 23 based on average planting date in 2024 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. 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 reached reproductive stages throughout most of the region. While it is still early to make strong inferences about end-of-season yields for irrigated corn, there is a relatively high probability of near-average yields for most sites, but this could change depending on temperatures during the next weeks.

For rainfed corn, the scenario is diverse across regions, with near-average yields likely in the northern, central and eastern regions of the Corn Belt. However, above-average yields are expected in southern and eastern NE, eastern KS and MO, whereas limited rainfall is leading to below-average yields in western NE and southern KS.

Temperature and rainfall through the end of July and early August will be crucial in determining whether these projections persist.

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 yield potential 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 the ones reported here in fields with planting dates or hybrid maturities that differ markedly from those used as the basis for the forecasts. We will follow up with further forecasts in early August.