8/21/25 - Cooler and Drier on the way...Warm fall?

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