Key Points
- Cooler temperatures are expected in the next 6-10 days, but first, heat is on the way this weekend.
- Day 3-7 hazards include high temperatures, severe weather, and flooding along the Mississippi.
- A warm signal persists through the next three months as ENSO neutral is expected to transition to La Niña by this fall.
Past Weather
So far this month, July has been around 4 degrees below average for most of the state, making the warmest month of the year feel relatively cool. During mid-July, daily high temperatures of around 85 degrees and daily low temperatures around 65 degrees are expected. In Ames, both the daily high and low temperatures have stayed at or below the expected temperatures this month. You can make a plot to see the daily temperatures for your town here.
Precipitation, on the other hand, continues to be above average across the state. For many areas, 150-300% of average precipitation has fallen in the past 14 days. Thankfully, northwest Iowa has received the least amount of rainfall during that period, receiving 2 or less inches of rain, or 50-100% of average. Impacts from significant and widespread flooding continue and resources for those effected by flooding can be found here. The most recent drought monitor map shows much of the “abnormally dry” areas are no longer present, apart from some dryness still present in Scott and Clinton Counties. Remember that the drought monitor does not consider conditions which occurred after the Tuesday prior to the Thursday release. Those conditions will be reflected in the next week’s report.
Crop Update
This week’s NASS crop progress shows corn conditions are 76% good to excellent, which is up 3% from last week. Soybean conditions are 76% good to excellent, which is up 4% from last week. There is variability across the state in terms of reproductive stages of crops due to variable planting dates and replating because of the rainy spring. 17% of corn acres are silking and 32% of soybean acres are blooming. Relatively mild temperatures and sufficient moisture have reduced or eliminated temperature stress concerns, as of now. However, a common concern across the state is disease pressure due to the warm and wet conditions.
In a recent blog post, Dr. Alison Robertson discussed some of these concerns. She noted that, “hot conditions we had in mid-June likely slowed tar spot development,” and that, “extended periods (30 days) of mild (64-73 degree) temperatures are favorable” for tar spot development. Climatologically, we would expect daily high temperatures of around 73 degrees to start happening again around the end of September.
Climate Outlook
The Weather Prediction Center quantitative precipitation forecast shows anywhere from 0.01-1.25 inches of rain falling across Iowa in the next 7 days. Northern Iowa is expected to receive the least amounts while southern Iowa is expected to receive greater amounts. Summer precipitation events are highly spatially variable, so local amounts may vary.
Before we see some cooler temperatures, hazardous heat is expected over the weekend (July 14-15).
The Weather Prediction Center day 3-7 hazards include high temperatures across all of Iowa, severe weather in northern to eastern parts of Iowa, and flooding along the Mississippi.
The 6-10 day outlook from the Climate Prediction Center shows chances for below average temperatures and near normal precipitation, so we can expect cooler temperatures between July 17-21. These cooler-than-average temperatures will not last long, though, so concerns of temperatures favorable for tar spot development are not yet a concern. The 8–14-day outlook (between July 19-25) shows temperatures moving back toward near normal and continuing to lean below average for precipitation. The 3–4-week outlook shows warm temperatures returning for the end of July into the beginning of August. The seasonal outlook shows a warm signal and equal chances for above or below average precipitation.
ENSO neutral conditions are expected to continue over the next several weeks, with a La Niña watch in place. La Niña has a 70% chance of developing during August to October. Once La Niña has developed, it is expected to persist into winter, which could increase chances for a colder winter in Iowa.
