Photo: Jared Winkler · CC BY-SA 4.0Midwinter lows in Castana sink below those of 93% of U.S. towns
The warmest part of a July day comes in at 85° on average. Its yearly precipitation falls short of 85% of U.S. towns. The latest 30-year average runs 1.0° warmer than 1901–2000’s, with March up the most. Tender plants can go out after about April 25; in half of years the first frost comes by October 12.
A year in Castana at a glance
Each month’s typical high and low, and what it brings.
What stands out about Castana’s climate
Compared with towns across the U.S., with Castana’s place in Iowa beside it.
What a year in Castana feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 170 frost-free days a year
In half of years the last 32° night comes by April 25 and the first by October 12. Frost and day counts come from NOAA’s station at Castana Exp Farm, IA, 4 miles from the town’s center, 310 ft higher.
The 2023 USDA map puts Castana’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −15°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 24 inches of snow a winter
Snow, measured at Kennebec, IA, falls mostly in December. Precipitation (rain plus melted snow) adds up to 31 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 80 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Castana
90% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Castana Exp Farm, IA.
Living with Castana’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
170 frost-free days in zone 5b. The last frost comes by Apr 25 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 12.
Months with highs of 62–84° and lows of 40° or more: May, June, August and September.
Parks & trails →Of the yearly building losses FEMA expects in Castana from natural hazards, river flooding is the largest share (41%); heat waves, cold waves, winter storms and ice storms together are 8%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Castana and similar climates
TownRatings has no climate map of the towns around Castana yet.
Climates most like Castana’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Castana, IA | 11° | 85° | 31" | 24" |
| Hastings, NE | 15° | 87° | 27" | 29" |
| Spring Valley, IL | 15° | 85° | 37" | 29" |
| Tecumseh, MI | 17° | 84° | 34" | 26" |
| Prairie du Chien, WI | 10° | 83° | 37" | 34" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Castana averaged 1.0° warmer than the 1900s. The biggest change is in March (+2.4°).
A smaller shift than in 79% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Castana compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Castana’s place among Iowa’s.
Castana weather by month
Highs, lows and precipitation from NOAA’s grid at Castana’s center; snow, wet days and snow on the ground from Kennebec, IA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 30° | 11° | 0.7" | 5.7" | 4 | 15 | 13° – 34° |
| February | 35° | 16° | 0.8" | 4.9" | 5 | 17 | 14° – 35° |
| March | 48° | 27° | 1.7" | 3.4" | 6 | 3 | 30° – 53° |
| April | 62° | 37° | 3.2" | 1.6" | 9 | 0 | 41° – 56° |
| May | 72° | 49° | 4.5" | 0.0" | 11 | 0 | 56° – 67° |
| June | 82° | 60° | 4.4" | 0.0" | 10 | 0 | 67° – 75° |
| July | 85° | 63° | 3.6" | 0.0" | 8 | 0 | 69° – 81° |
| August | 83° | 61° | 4.0" | 0.0" | 7 | 0 | 66° – 77° |
| September | 77° | 52° | 3.1" | 0.0" | 6 | 0 | 58° – 70° |
| October | 64° | 40° | 2.3" | 0.5" | 6 | 0 | 44° – 56° |
| November | 47° | 26° | 1.4" | 0.9" | 4 | 1 | 27° – 48° |
| December | 34° | 16° | 1.1" | 6.9" | 5 | 12 | 11° – 31° |
| Year | 60° | 38° | 31.0" | 23.9" | 80 | 48 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 30° to 53°. June is the most reliable, staying within 8°.
Where Castana’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Castana’s center.
- Snow: Kennebec, IA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Castana Exp Farm, IA, 4 miles from the town’s center, 310 ft higher; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Castana’s climate
What is the weather like in Castana?
A typical July afternoon reaches 85°, a January night drops to 11°, and about 24 inches of snow falls in a normal winter. Colder January nights than 93% of U.S. towns; hotter July afternoons than 51% of U.S. towns.
How cold does it get in Castana in winter?
January nights average 11°. About 144 nights a year reach 32° or below and 16 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How much snow does Castana get?
About 24 inches in a normal winter at Kennebec, IA, most of it in December, with snow on the ground about 48 days a year.
How hot does it get in Castana?
July, with a typical high of 85° and a low of 63°. About 13 days a year reach 90° (Castana Exp Farm, IA).
When is the first and last frost in Castana?
In half of years the last spring frost (32°) comes by April 25 and the first fall frost by October 12, about 170 frost-free days, at Castana Exp Farm, IA.
What growing zone is Castana in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −15°.
What is the best time of year to visit Castana?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Castana getting warmer?
Yes: 1991–2020 averaged 1.0° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 79% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Castana.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.