Summer Precipitation in Iowa? Still A Work in Progress

Today’s guest post is by Dr. Dennis Todey, USDA Midwest Climate Hub Director, with timely climate information for crop year 2017.

The spring and early summer in Iowa has been one of large opposing extremes from warm February to cool in early May to near record heat in early June.  Precipitation has also been excessive at times, but much less extreme than the wetness of the eastern Corn Belt and dryness of the northern plains so far this spring.

Crop planting progress in Iowa was slightly delayed because of cooler and wetter conditions during planting.  The early season warmth slowed and very cool early May conditions took over with soil temperatures falling below the critical 50 F level for development for several days.  After early May, dry conditions have been prevalent with most of the state below average precipitation accumulation over the last 30 days into early June. The dryness was beneficial in allowing planting to progress more readily and crops to develop. Rains returned in mid-June easing the dryness somewhat.

Precip dots

Drought in the Northern Plains and near 100 F heat in mid-June has created some concern about drought/heat conditions impacting crop condition.  At this point the extreme heat will have only a limited impact on crop yield.  The additional heat will be beneficial (to a certain extent) in helping overcome delayed crop development.

A Look Ahead

Looking ahead to the rest of the growing season is a bit difficult because summer precipitation projections are limited.  At this point, it doesn’t seem like the hot and dry of early June will stick around for the whole summer. There are some hints of hotter and drier conditions returning in July in Iowa and more of the Midwest.  However, current projections would not carry those into August.  Both July and August conditions are only slightly better than 50-50 chance of being accurate. Current NOAA outlooks indicate warmer than average temperatures more likely in July and July – August.  The 90 day outlooks have a small chance of above average temperatures in far northwest Iowa.

temp outlook 6-2017

The overall impact in Iowa and the Corn Belt is still developing.  The late planting of the eastern Corn Belt will be somewhat overcome by the current warm temperatures.  The northwest Corn Belt may see some problems with heat and drought because of the early June developing drought conditions.  Iowa is still a work in progress.  If the July heat does occur, some yield loss will be likely.  Overall yields in the Corn Belt have likely been trimmed because of the variety of problems.

Corn GDD Tracking

For anyone growing corn with questions where they are in GDD development, there is a tool from a recently-completed USDA NIFA-funded project that allows producers to check their crop progress daily based on Growing Degree Day accumulation.  The Corn GDD Tool allows a producer to pick their location, corn maturity and planting date. After choosing these the tool creates a plot of GDDs compared to average up to the previous day, a projection for the growing season GDD accumulation to tasseling and freeze date and comparison to selected analog years.  This tool is unique in its local data accumulation and projection of GDD accumulation through the year.