Iona, SD climate
Iona has cold, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 88°, a January night drops to 11°, and about 43 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Iona feels like
Winter
Spring
Summer
Fall
Iona weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 32° | 11° | 0.4" | 7.3" | 6 | 18 | 13° – 37° |
| February | 36° | 15° | 0.6" | 8.0" | 6 | 12 | 11° – 36° |
| March | 48° | 25° | 1.0" | 7.2" | 6 | 10 | 25° – 51° |
| April | 60° | 35° | 2.6" | 6.8" | 10 | 2 | 38° – 53° |
| May | 71° | 46° | 3.5" | 0 | 11 | 0 | 54° – 65° |
| June | 81° | 57° | 3.8" | 0 | 11 | 0 | 64° – 74° |
| July | 88° | 63° | 2.8" | 0 | 9 | 0 | 66° – 82° |
| August | 86° | 61° | 2.8" | 0 | 8 | 0 | 67° – 77° |
| September | 78° | 51° | 2.3" | 0 | 7 | 0 | 58° – 70° |
| October | 63° | 38° | 1.8" | 1.4" | 7 | 1 | 42° – 56° |
| November | 47° | 25° | 0.7" | 5.1" | 5 | 5 | 25° – 45° |
| December | 34° | 15° | 0.5" | 7.5" | 6 | 15 | 13° – 31° |
| Year | 60° | 37° | 22.7" | 43.3" | 93 | 64 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Iona
Iona gets 23 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 93 days a year. Snow covers the ground about 64 days of the year.
About 158 frost-free days a year
In half of years the last 32° night comes by May 1 and the first one by October 7. That leaves about 158 frost-free days for gardens, shorter than 73% of U.S. towns.
Heating and cooling a home in Iona
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Iona, 89% of that work is heating and 11% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Iona and its neighbors
Iona borders 5 towns with climate data. January nights across them vary by 1.3°. Oacoma has the coldest January nights (10°) and Landing Creek the hottest July afternoons (88°). Iona’s January low is 11° and its July high 88°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Iona compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Iona averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.7°). The shift is larger than in 60% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Iona’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 25° to 51°. June is the most reliable, staying within 10°.
Common questions about Iona’s climate
What is the coldest month in Iona?
January, with a typical high of 32° and a low of 11°.
What is the hottest month in Iona?
July, with a typical high of 88° and a low of 63°. About 34 days a year reach 90°.
How much snow does Iona get?
About 43 inches in a normal winter, most of it in February.
When is the first frost in Iona?
In half of years the first 32° night comes by October 7, and the last spring frost by May 1.
What is the rainiest month in Iona?
June, with 3.8 inches of rain and melted snow. The year totals 23 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Iona itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Chamberlain 5 S, SD (11 mi, snow) and Chamberlain Municipal Airport, SD (13 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.