How Hot and Dry? Reviewing Summer 2023 Drought and Weather
With the proverbial dust settling on the 2023 growing season, we wanted to review the drought and weather data to size up conditions. If you’re like us, you’re tired of seeing all the drought maps and weather models, so we promise to take a different approach.
In full disclosure, the post summarizes work done throughout the summer by the AEI team. Links to relevant articles will be included, as these insights were a team effort.
The Largest Drought Since 2012
As we’ve said countless times, the weekly drought monitor maps can easily mislead our thinking in two ways. First, historical context or benchmarks are rarely included, so statements like “X% of the U.S. corn crop are in drought” aren’t insightful as there is always some share in drought. Second, and perhaps more consequential, the relationship between the share of U.S. crops in drought and final yields is weak. As Brett found, there are better frameworks for thinking about drought’s effects on yields – corn: here, soybeans: here.
In an effort to provide meaningful context, Figure 1 plots, on a monthly basis, the proportion of corn acres in drought since 2000. In June, the magnitude of the drought was the largest since 2000, ahead of even 2012. But consider what happened in the subsequent months. In July, drought conditions were mostly unchanged before a reduction in August. Now, contrast that to 2012, when the drought’s grip significantly expanded throughout the summer. While drought conditions were widespread and persistent this year, conditions didn’t get worse as the corn and soybean crops entered their reproductive stages.
Rainfall and Temps
Digging deeper, Table 1 summarizes state-level June precipitation data. Rainfall in Illinois – which accounts for 19% of corn acres – was 2.63 inches below average. Similarly, rain in Iowa – accounting for 22% of corn acres – was 2.22 inches below average. Only Nebraska and South Dakota – collectively accounting for 25% of corn acres – had average or above-average June rainfall. Across the major corn states, June precipitation averaged 2.7 inches, compared to the average of 4.37. (Read the original article here.)
In July, both temperatures and rainfall are significant when estimating national yields. Since 1988, the average July temperature across the major corn-producing states is 73.8 degrees. At 72.7 F, 2023 was slightly cooler than average.
July rainfall was again below average, but the deficit wasn’t as severe as in June. At the state level, Indiana, Nebraska, and Ohio were around 0.7 inches below the long-run average, while Iowa and Minnesota were both an inch or more above average. For more details and a discussion about yield implications, read Jeff’s full article.
Lastly, when compared to the extremes of 2012, 2023 was considerably cooler and wetter:
- July temperature: 2012 – 79.5 F; 2023 – 72.7 F
- July precipitation: 2012 – 1.81 inches; 2023 – 3.62 inches
Wrapping It Up
Admittedly, these data and insights come with hindsight. In a perfect world, we could have perfectly forecasted these outcomes and modeled the effect on corn and soybean yields. However, we are, instead, in an imperfect world striving to improve our thinking with a better understanding of the data.
While 2023 conditions were adverse in many ways, they remained a far cry from the extremes of 2012. It’s also another reminder that “the worst since 2012” can still be a long way from 2012-like conditions.