Persistent heat ridge threatens crop development while storms, flooding, and a strengthening El Niño add uncertainty to North American agriculture.
A powerful heat ridge dominating the central United States is creating growing concerns for crop development across major agricultural regions, according to the latest weather outlook from Nutrien meteorologist Eric Snodgrass.
While parts of North America received much-needed rainfall over the past week, other regions experienced record-breaking temperatures, flash flooding, and worsening wildfire smoke conditions, highlighting the increasingly complex weather picture confronting farmers through the remainder of July.
"The ridge is the main story," said Snodgrass, referring to an unusually strong upper-level high-pressure system that has become anchored over portions of the Upper Midwest.
The weather pattern tied or broke all-time heat records in several locations over the weekend and has triggered excessive heat watches and warnings stretching from the northern Four Corners region through Idaho, Wyoming and Montana, extending across the northern United States into the Northeast.
For agriculture, the biggest concern is not simply the heat itself, but how long it remains in place.
Flash Drought Risk Emerging
Snodgrass said a large "dry donut hole" is expected to persist across the middle of the United States over the next two weeks, with the western Corn Belt expected to experience the driest conditions.
Although forecasts do not suggest an absence of rainfall, precipitation is expected to fall below normal levels at a time when many crops are entering critical growth stages.
NASA soil-moisture projections indicate the combination of persistent heat and reduced rainfall could rapidly deplete available moisture supplies across portions of the western Corn Belt and Northern Plains, increasing the threat of flash drought development.
Flash droughts can develop quickly, causing crop stress to intensify within weeks rather than months. Corn and soybean crops become particularly vulnerable when hot temperatures coincide with declining soil moisture reserves.
Snodgrass noted that history suggests caution when forecasting extended dry periods because storm systems traveling around the edge of the heat ridge can occasionally bend southward from Canada and deliver unexpected moisture.
However, he warns if the hot and dry pattern becomes entrenched, crop conditions could deteriorate rapidly.
Corn Yield Potential Under Pressure
The current heat wave arrives as some parts of the Corn Belt are already accumulating elevated levels of crop stress.
According to Snodgrass, Des Moines has already recorded stress degree day accumulations roughly 20 units above normal through early July. Additional extreme temperatures could push corn crops closer to thresholds historically associated with yield reductions.
Warm overnight temperatures may become an equally important factor.
Agronomists often monitor nighttime lows because crops have less opportunity to recover from daytime heat stress when temperatures remain elevated after sunset. Snodgrass identified overnight temperatures above 74°F (23°C) as a key indicator farmers should watch.
"If this forecast fails and the heat stays anchored over the Midwest and Northern Plains, expect rapidly declining crop conditions and more significant yield-loss risk," he warned.
Computer models currently indicate the hottest conditions may gradually shift northwest later in the month before easing somewhat between July 20 and July 27. However, considerable uncertainty remains.
Storm Activity Continues Around Ridge
While the central United States faces increasing dryness, more active weather is expected around the outer edges of the heat dome.
Meteorologists often refer to these systems as "ring of fire" storms because they travel around the perimeter of a dominant ridge.
These storm tracks are forecast to impact the Canadian Prairies, Great Lakes region, Ohio Valley, Appalachians and Mid-Atlantic states.
Meanwhile, the Southwest monsoon remains active and could extend farther west than normal.
Beneficial rainfall over the past week has already improved moisture conditions across drought-affected areas of the Southeast and Mid-Atlantic. Additional precipitation is expected across those regions in the coming weeks.
Snodgrass is also monitoring a potential weak tropical low-pressure system that could form along the Gulf Coast early next week.
Although no hurricane development is anticipated, the system could generate periods of heavy rainfall from the Gulf Coast into portions of the southeastern United States.
Flooding and Wildfire Smoke Add Challenges
The past week also brought significant flooding to portions of eastern Tennessee and scattered areas across Missouri, southern Illinois and Kentucky.
At the same time, large wildfires burning along the Ontario-Minnesota border and across parts of Ontario and Quebec have continued to degrade air quality across portions of Canada and the northern United States.
Such contrasting extremes underscore the uneven weather conditions affecting agricultural production across North America.
Some regions are receiving abundant moisture while others grapple with increasing heat stress and declining soil moisture.
El Niño Growing Stronger
Looking beyond July, Snodgrass believes a strengthening El Niño will become one of the most important factors shaping agricultural weather through the remainder of 2026 and into 2027.
NOAA currently places the probability of El Niño development and persistence through February 2027 at nearly 100 per cent.
Sea surface temperatures in the Niño 3.4 region are already running approximately 2°C above average and continue to strengthen. Snodgrass noted that current measurements are approaching levels often associated with so-called "Super El Niño" events.
At the same time, global atmospheric indicators suggest the current heat ridge could gradually weaken and retreat westward later this month as atmospheric momentum declines.
However, he cautioned that weather patterns occasionally become locked in place longer than expected.
What Farmers Should Watch
For producers across North America, the key question over the next several weeks will be whether storm systems can penetrate the heat ridge and replenish soil moisture before crop stress intensifies.
If forecasts verify and the ridge weakens, pressure on crops could ease. If not, portions of the western Corn Belt and Northern Plains could face increasing drought concerns at a critical point in the growing season.
With major heat, active storm tracks, wildfire smoke, a tropical moisture threat and a rapidly strengthening El Niño all influencing the forecast simultaneously, weather will remain one of the most significant variables shaping agricultural markets and crop prospects through the remainder of the summer.
Photo Credit: Nutrien - Eric Snodgrass