Frost dates for Clinton #1, Iowa
Half of years have their last spring frost by April 22, but 1 year in 10 still frosts after May 8.
A frost date is really a percentile from 30 years of records at a nearby weather station: in about half of years a frost still comes after the median date. Both numbers are below, so you can choose the risk yourself.
The odds
Last spring frost
How often a frost still comes on or after each date.
- 1 year in 10
- May 8
- 1 year in 5
- May 2
- 3 years in 10
- April 29
- 2 years in 5
- April 26
- Half of years (the median)
- April 22
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- October 2
- 1 year in 5
- October 7
- 3 years in 10
- October 11
- 2 years in 5
- October 13
- Half of years (the median)
- October 16
- Growing season
- about 175 days
- Hardiness zones nearby
- 5a, 5b
- Summer days
- a usual high of about 28 °C82 °F
- Lettuce and spinach run to seed
- June to September, in hot, long days (how we know)
Summer and rain
A growing garden needs about 25 mm1 in of water a week, rain and watering together. Here is what a normal month brings.
Month by month
- January
- high ~-1 °C29 °F · low ~-10 °C14 °F · rain ~37 mm1.4 in
- February
- high ~1 °C34 °F · low ~-8 °C18 °F · rain ~43 mm1.7 in
- March
- high ~9 °C48 °F · low ~-2 °C29 °F · rain ~59 mm2.3 in
- April
- high ~17 °C62 °F · low ~4 °C40 °F · rain ~86 mm3.4 in
- May
- high ~23 °C73 °F · low ~11 °C51 °F · rain ~112 mm4.4 in
- June
- high ~27 °C81 °F · low ~16 °C61 °F · rain ~120 mm4.7 in
- July
- high ~29 °C84 °F · low ~18 °C65 °F · rain ~99 mm3.9 in
- August
- high ~28 °C82 °F · low ~17 °C63 °F · rain ~107 mm4.2 in
- September
- high ~24 °C76 °F · low ~13 °C55 °F · rain ~94 mm3.7 in
- October
- high ~17 °C63 °F · low ~6 °C43 °F · rain ~67 mm2.6 in
- November
- high ~9 °C48 °F · low ~-1 °C31 °F · rain ~56 mm2.2 in
- December
- high ~1 °C35 °F · low ~-6 °C20 °F · rain ~47 mm1.9 in
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Clinton #1 station (listed by NOAA as Clinton #1 HCN, USC00131635), at 41.79, -90.26. These are that station’s own records, unshifted. The further your garden is from it, the less exactly they describe your ground. The planner finds the nearest station to your garden and lowers its confidence with distance, so no number is presented as if it were measured in your garden.
Cold air also pools in low ground on the clear, still nights when frost happens, so a hollow can freeze while a slope a few hundred feet away does not. No table can know that about your garden. A few seasons of your own logged frosts can.
ZIP codes nearest this station
52037, 52069, 52701, 52727, 52730, 52731, 52732, 52742, 52750, 52757, 52758, 52768…
+6 moreShow fewer
52774, 61230, 61242, 61252, 61257, 61275.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Davenport, IA, last frost by April 23
- Aledo, IL, last frost by April 22
- Hennepin Wtr Trmt Plt, IL, last frost by April 24
- Rockford Greater Rockford Airport, IL, last frost by April 24
- Cedar Rapids Municipal Airport, IA, last frost by April 27
- Peoria Greater Peoria Airport, IL, last frost by April 16
Other stations in Iowa.
- Des Moines Johnston, IA, last frost by April 19
- Sioux City Gateway Airport, IA, last frost by April 29
When do I plant? · Where the dates come from
More ways Milpa can help
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