What in the Weather?

Weather History & Forecast:

• 1942: Early snowfall hit Iowa on this date, with up to 4 inches accumulating in some areas
• Coming week: Unseasonably warm and dry with sunny days, temperatures above normal
• Extended outlook: Strong warm signal through early October, particularly in upper Midwest

Recent Weather:

• Past week: 8-12 degrees above average statewide
• First above-average rainfall period in weeks (with the highest, 4.54", in Fort Dodge!)
• Eastern Iowa remained drier than western areas

Specialty Crop Updates:

• Peppers: Good yields continuing due to warm weather; some cyclamen/broad mite issues observed in Newton area
• Carmen peppers: Unusual spiciness reported - growers advised to check
• Melons: Reduced solar radiation from cloudy, wet summer conditions may have contributed to poor season (theory posited by Jordan Lyon, Buser's Produce)
• Tomatoes: Splitting issues due to uneven rainfall patterns

Frost Outlook:

• No widespread frost expected through October 11th based on dew point forecasts
• Warm, dry conditions may still allow nighttime cooling near normal levels

Upcoming Events:

• October 4: Nut Growers of Iowa field day (Centerville/Ottumwa)
• October 7: Shimek Forestry field day (southeast Iowa)
• October 9: Yellow River Forestry field day (northeast Iowa)

Greenhouse/High Tunnel Tip:

• Control weeds now to prevent pest and disease carryover through winter

Podcast Summary generated using claude.ai

• Historical Weather Moment: In 1912, Iowa experienced extreme weather swings from 104°F heat to snow flurries within just 9 days in September

• Current Forecast: Unsettled weather with cut-off low pressure system bringing increased precipitation chances, potential storms with wind and small hail, but overall benign conditions

• 8-14 Day Outlook: "Red bullseye" over Iowa and Minnesota indicating high likelihood of above-normal temperatures (mid-upper 70s vs normal) through September 30th

• Recent Weather Events: Northern Iowa hit with 1+ inch hail reports across multiple counties; Fort Dodge area received 4+ inches of rainfall; most of central Iowa remained dry

• Summer Glory Index Results: Iowa's meteorological summer rated as "fine" with SGI of 1420, held back primarily by July's high dew points and overnight lows; only 3 days reached 100°F in Western Iowa

• Fall Foliage Prediction: Favorable conditions for vibrant fall colors with warm days, cool nights, and sunshine; early color changes already spotted on individual tree branches

• Specialty Crop Update: Poor pumpkin harvest continues due to fruit set issues and rot problems; fall brassicas showing alternaria from earlier wet conditions but later plantings look strong; fall carrots performing well

Summary generated using Claude.ai

Weather Forecast & Climate Updates

• Hot and dry conditions ahead with temperatures in low-mid 90s and heat index values in mid-upper 90s

• 8-14 day outlook shows continued warmth into late September with slight chance for above normal precipitation

• ENSO update: 71% chance of La Niña transition October-December, signaling potential warm and dry fall/winter

This Week's Weather Recap

• Chilly temperatures that felt great after a hot summer

• Mostly dry conditions with under 0.4 inches for most of the state

• First freeze of season recorded at Stanley, Iowa (32°F on September 7th)

Specialty Crop Impacts

• Pumpkins: Strong auction prices ($5-10 vs typical $2-3) but poor growing season with fruit set issues

• Cucumbers: Cold damage causing unmarketable scarring at Featherstone Farm

• Melons: Season ended 6+ weeks early, creating H-2A labor contract challenges for growers

• Watermelons: Poor year especially in low-lying areas due to fruit rot

• Flowers: Mixed reports - Rose Farm had great year, others experienced delays

• Honey production: Drastically reduced to 1/5 of expected yields, indicating widespread pollinator issues

Historical Weather Note

• September 11, 1917: Earliest freeze on record hit eastern Iowa with temperatures as low as 30°F, causing considerable damage to corn, potatoes, and other late crops

Coming Next Week

• Summer Glory Index results and fall foliage outlook

Podcast summary generated using Claude.ai

Weather History & Forecasts

• Iowa Weather History (1989): Large thunderstorms brought heavy rain to western Iowa with severe weather and brief tornadoes, causing wind damage, roof damage, and trees falling on cars
• 7-Day Forecast: Cool autumn weather with clear skies and below-average temperatures; best rain chances on days 4-6 due to Atlantic activity and shifted Bermuda high
• Climate Outlook: September 9-13 shows slightly warmer temperatures and higher precipitation chances in western Iowa; monthly outlook suggests equal temperature chances and wetter conditions statewide

Weather Summary & Notable Events

• Past Week: Most of Iowa received below-normal rainfall (0.5" below average), except western/southwestern Iowa which saw above-average amounts
• Cold Snap: Some locations hit around 40°F, causing potential localized damage to sensitive plants like basil but not widespread frost damage
• Summer 2025 Overview: 10th wettest summer in 153 years with 18.5" total precipitation (5" above average); July was 2nd wettest on record; August was drier at 3.4" (0.75" below average)

Heavy Dews Explanation

• Seasonal Pattern: Heavy dews occur in late August/early September due to shorter daylight hours and cooling surface temperatures
• Science: Earth radiates heat overnight while warm air masses remain overhead, reaching dew point and creating heavy condensation
• Crop Impact: Wet leaves from heavy dews can promote foliar pathogens and crop decline

Specialty Crop Topics

• Foxtail Grass Seeds: Grower concerned about viability of mowed green foxtail; recommended germination testing with moist paper towel method
• Compost Management: While beneficial, compost can raise soil pH and create phosphorus excess due to 1:1:1 N-P-K ratio; rule of thumb: 1% organic matter = 20 lbs nitrogen per season
• Nitrogen in Rainfall: Addressed grower question about delayed flower blooming; rainfall contains minimal nitrogen (0.5-3 mg/L) compared to irrigation water nitrate levels (10+ mg/L); plant greening after rain is primarily due to improved nutrient availability from soil moisture, not atmospheric nitrogen
• Cover Crops: Good timing now for oats and peas establishment; winter rye timing approaching; recommend seeding when rainfall is expected

Episode Summary created by Claude.ai

Weather Forecast & Conditions:

• Cold front moving south from Minnesota will stall over Iowa, bringing rain chances Friday-Sunday
• Expected rainfall: up to 1-1.5 inches in northwest Iowa, less than 0.5 inches elsewhere
• Cool temperatures continuing into early September (50-60% chance of below normal temps)
• First overnight lows in the 40s recorded this past week

Historical Weather Note:

• August 28, 1979: Violent F3-F4 tornado tracked 45 miles across southwestern Iowa, killing 2 people and causing millions in damage

Growing Season Challenges:

• One grower called this "the worst growing season in recent memory" due to excessive rain and heat
• Watermelon season ending 1.5 months early due to persistent rainfall (14 inches over 2-3 weeks)
• Widespread crop diseases including Phytophthora on pumpkins, pepper anthracnose, bacterial spot, and southern rust on sweet corn

Specialty Crop Impacts:

• Cut flower growers dealing with high soil pH (7.7) and nutrient leaching
• Recommendations to remove diseased peppers to prevent further spread
• Discussion of sprayer technology resources for disease management

Looking Ahead:

• Hope for warm, dry fall to help struggling crops mature
• Next week will feature meteorological summer season review and in 2 weeks, the Summer Glory Index results

Podcast summary generated using Claude.ai

What in the Weather? - August 21, 2025 Episode Summary Weather Discussion

• Historic perspective: August 21, 2004 saw unusually cool temps (upper 30s) in northern Iowa - opposite of current conditions
• Hot summer analysis: July averaged 2°F above normal with exceptional humidity (85% of days had above-average dew points)
• Heat index impact: Triple-digit heat index values driven more by high dew points (upper 70s-low 80s) than air temperatures
• Moisture source: Gulf moisture "gate wide open" with southerly winds bringing exceptional humidity to upper Midwest

Forecast

• Weekend cooldown: Dramatic temperature drop to highs in 70s, overnight lows in upper 40s-mid 50s
• Extended outlook: Southeastern Iowa likely colder late August, September outlook shows warm/dry trend
• Precipitation: Minimal rainfall expected (0.1-0.25") with best chance Friday night into Saturday
• La Niña watch: Potential fall development could affect late October/November weather patterns

Specialty Crop Impacts

• Disease issues: Rhizoctonia root rot affecting snapdragons; tomato brown rugose fruit virus causing uneven ripening
• Pest spotlight: European corn borer infesting dahlia stems and peppers - biological control with Trichogramma wasps recommended
• Growing challenges: Excessive moisture limiting planting windows; late-planted fall crops struggling to establish
• Crop performance: Good pepper year for some growers, but eggplant and tomato fruit set suffering from heat stress

Resources

• Penn State cut flower production newsletter
• Utah State University cut flower resources

Coming in September to your favorite podcast platform: Pivot Points, a new podcast exploring the stories of farmers who have made big changes to their farms and in their lives.

Follow the Pivot Points podcast to make sure you get the podcasts as soon as they are released.

Iowa's top 10 historical rainfalls

• 10th Place: Sheridan (Lucas County) - 11.23 inches on August 27th, 1903

• 9th Place: Ionia (Chickasaw County) - 11.25 inches on August 9th, 2021

• 8th Place: Dumont (Butler County) - 11.28 inches on July 17th, 1968

• 7th Place: Castana Experimental Research Farm (Monona County) - 12.02 inches on July 17th, 1996

• 6th Place: Bonaparte (Van Buren County) - 12.1 inches on June 10th, 1905

• 5th Place: Hudson (Black Hawk County) - 12.28 inches on June 1st, 2000

• 4th Place: Rathbun Dam (Appanoose County) - 12.34 inches on August 24th, 2007

• 3rd Place: Le Mars (Plymouth County) - 12.41 inches on January 5th, 2009

• 2nd Place: Audubon - 12.53 inches on July 2nd, 1958

• 1st Place: Atlantic 1 NE (Cass County) - 13.18 inches on June 14th, 1998

Main Topic: "Corn Sweat" Phenomenon

• Definition & Media Coverage
  • "Corn sweat" is simply a catchy term for evapotranspiration
  • Justin Glisan was interviewed by major news outlets (Washington Post, CNN, USA Today, CBS)
  • The phenomenon was trending during the hottest week of July 2025 during a heat dome
• Scientific Reality
  • Corn releases water vapor and oxygen through transpiration (not actually "sweating")
  • Adds 3-5% to relative humidity locally (3-5 degrees to dew point)
  • Peak evapotranspiration occurs during corn pollination/tasseling season
  • Iowa has 13 million acres of corn contributing to this effect
• Comparative Analysis
  • Prairie grasses actually have slightly higher evapotranspiration rates than corn
  • Corn and soybeans have very similar ET rates during peak growth
  • Historical prairie landscape would have different hydrology and soil structure
  • Modeling is used to understand these complex comparisons since full-scale experiments aren't feasible
• Weather Forecasting History
  • First tornado warning issued in 1940s by Miller and Fawbush at Air Force base
  • WWII and 1946 weather radar development improved forecasting capabilities
  • 1925 Tri-State tornado killed ~700 people despite warning signs, but no communication system existed
  • Modern forecasting balances accuracy with avoiding "boy who cried wolf" scenario
• Social Media & Public Education
  • Madelynn Wuestenberg urges people to stop sharing corn sweat TikToks
  • Working on program to fact-check weather-related social media content
  • Emphasizes need for agricultural meteorologists with both meteorology and agronomy backgrounds

Summary generated by Claude.ai

Historical Weather (This Day in History - 1993)

• Severe thunderstorms moved from Nebraska to western Iowa at 60 mph
• Wind gusts exceeded 70 mph, with 75 mph winds in Pottawattamie County destroying barns
• Council Bluffs received 2 inches of rain in 30 minutes causing urban flooding
• Des Moines recorded 83 mph wind gust
• 1993 was record wet year for Ames (20 inches of rain in July alone vs. 8 inches in July 2025)

Current Weather Forecast Short-term (Justin Glisan)

• Rainfall chances continue through Friday night
• Cold front broke heat dome, bringing dew points down
• Temperatures: mid-80s through weekend, then back to 90s
• Minor rainfall chances early next week
• Northern Iowa has less rain chance as storm track moves south
• Expected rainfall: 3/4 inch statewide (below normal), 1.5-2 inches in southwestern Iowa

Extended Outlook (Madelynn Wuestenberg)

• 6-10 day outlook (July 29-Aug 2): Slightly below normal temperatures in north, near normal in south; 33-40% chance above normal precipitation
• 8-14 day outlook (July 31-Aug 6): Continued slight chances of below normal temperatures; western Iowa slightly wetter, eastern Iowa near normal
• Normal temperatures: Daily highs mid-80s, lows in 60s

Recent Weather Events Heat and Humidity

• Yesterday and prior day were hot, with cloud cover mitigating worst conditions in central Iowa
• Eastern Iowa experienced "dew point pooling" with dew points in upper 70s-low 80s
• Hottest reading: Dubuque Lock and Dam hit 95°F with heat index of 110°F

Severe Weather

• 6 AM tornado warnings in central Iowa
• Tornado warnings near Maxwell and eastern Iowa
• Caused by remnants of mesoscale convective vortex from Kansas moving along warm boundary

Rainfall Totals (Past 7 Days)

• Northeast Iowa: 4-4.5 inches (highest)
• Central Iowa: 3-3.5 inches
• Southwest Iowa: Trace to 0.25 inches (lowest, drought conditions persist)

Specialty Crop Impacts Garlic Disease Investigation

• Farm in Chariton, Iowa had garlic crop with yellowing (suspected aster yellows)
• Testing revealed it was a virus, not aster yellows phytoplasma
• Cannot save seed for next year due to virus
• Comparison with aunt's clean stock showed dramatic difference
• At a different farm, possible Embellisia skin blotch observed on garlic wrappers

Brassica Issues

• Black rot & alternaria affecting collards, broccoli, and kale
• Wet conditions exacerbating disease problems

Nutritional Concerns

• Nitrogen leaching due to excessive moisture
• Fertilization may be necessary to supplement leached nutrients

Crop Performance Issues

• Onions in Central Minnesota: Unexpectedly bolting across all varieties (planted from seed this spring)
• Zucchini: Poor fruit set, currently "worst crop of the year" candidate
• Tomatoes: Slow growth, fruit remaining green
• General pollination: Poor across multiple crops due to hot, wet conditions
• Heat may be affecting fruit set in tomatoes and peppers (flower abortion)

Upcoming Events

• July 30: Cut flower field walk at River Root Farm (Decorah)
• July 31-Aug 1: Plant Peddler educator field day and variety day (Cresco)
• August 2: Grow Johnson County field day and food safety workshop
• August 5: Iowa State fruit and vegetable Field Day
• August 20: Midwest mechanical weed control field day

Show Notes

• Hiatus announcement: No new episodes for 3 weeks (pre-recorded content only)
• Return date: August 21st, 2025

summary generated using Claude.ai