5/1/25 - Weather like San Diego ahead?!

This Day in Iowa Weather History

• In 1911, unseasonably cold air brought rain mixed with snow across northwestern Iowa. Most snow melted on contact, but some locations reported accumulations: 1 inch at Denison, 1.5 inches at Alta and Lamars, 2 inches at Algona, Mason City, New Hampton, Onawa, and Rockwell City, 2.5 inches at Rock Rapids, and 4 inches at Elma in Howard County.

7-Day Weather Forecast

• Showers and thunderstorms are possible today, but the weekend will bring pleasant, San Diego-like weather: sunny skies and highs in the 70s. A quieter weather pattern is expected to settle in.

Climate Outlook

• 8–14 Days (May 8–14): Strong likelihood of above-normal temperatures. The eastern half of Iowa leans slightly below normal for precipitation, while the western half is near normal-overall, a little dry and definitely warm.

• 3–4 Weeks (May 10–23): The outlook leans warm with equal chances for precipitation. Precipitation remains difficult to forecast due to the spring transition.

• May Monthly Outlook: Most of Iowa is likely to be warmer than normal. Precipitation is split: the northeast leans slightly drier, while the southwest has equal chances for above, below, or normal precipitation.

Recent Weather Impacts

• On Monday, Iowa experienced very windy conditions (gusts up to 70 mph in Ames) but no tornadoes. The severe weather event was well forecasted in terms of risk areas, but many Iowans did not experience significant storms, leading to a perception of overhype.

• The lack of severe storms in Iowa was attributed to a strong atmospheric cap, cloud cover, dust, and wind alignment that prevented updrafts, despite all other ingredients for severe weather being present.

Specialty Crop Impacts

• Winter Rye: Beginning to flower across Iowa. Growers can terminate rye reliably by mowing and tilling at anthesis (pollen shed). One grower plans to mow and bale rye for weed-free straw mulch.

• Overwintered Flowers: Iceland poppies are starting to open; dianthus are looking good. More flower updates are expected next week, ahead of Mother’s Day.

• Greenhouse Tomatoes: Ripe tomatoes are being harvested in greenhouses in Grinnell and likely at some auction houses.

• Garlic & Aster Yellows: Growers are on watch for aster yellows phytoplasma, which devastated garlic crops last year, especially in northeast Iowa and neighboring states. Recent lab tests found rotted garlic cloves infected with pythium and rhizoctonia, not aster yellows. The likely cause was winterkill due to low snow cover, not disease. Spring-planted garlic had much higher survival.

• Management Advice: Rogue out yellow, weak garlic plants now to prevent potential spread of aster yellows by leafhoppers. Mulch and snow cover help protect overwintered garlic.

• Soil Testing: New online and spreadsheet tools are available for interpreting soil test results and generating fertilizer recommendations.

• MASC Payments: A new round of Market Assistance for Specialty Crops (MASC) payments has been announced. Growers should check with their FSA office for eligibility.

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