Frost Dates for 50156 — Madrid, Iowa

Half of springs at Ames 8 WSW, IA see their last 32°F night by April 23; only one in ten is past it by April 7, and one in ten still has one after May 5. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 2 20%, and after May 5 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 67% of the 132 Iowa stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 14 in half of years, as early as September 29 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 10 days later, around October 24; in spring the one-in-ten date for 28°F is April 27, 8 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, longer than at 76% of the 132 Iowa stations; it reaches 193 days one year in ten and falls short of 155 one year in ten. On average 141 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 10 days longer, to about May 3, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 18 and March 15.

July is the warmest month at Ames 8 WSW, IA, averaging 84°F by day and 64°F at night; January is the coldest at 29°F and 12°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 25% of years.

Warmth for growing adds up to 3,235 growing degree days a year (base 50°F), more than at 77% of the 132 Iowa stations. 36% of them (1,156) have built up by the end of June, and July adds the most, 744. Precipitation totals 36.0 inches a year, most in May (5.0") and least in January (0.7"); May to September bring 63% of it.

The nearest other station, Des Moines Wsfo-Johnston, IA, 10 miles south of Madrid, has a last frost 4 days earlier (April 19), a first frost 4 days later (October 18), a season 6 days longer.

The first measurable snow (0.1 inch or more) in Madrid usually arrives around November 20, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Ames 8 WSW, IA, 10 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 18 days after the last snow.

ZIP 50156 is 10 miles from Ames 8 WSW, IA, which stands at 1,099 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 50156 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.