Weather without surprises: Gilliam keeps close to the norm for U.S. towns
July afternoons average 88°. Summer afternoons here are warmer than in 65% of U.S. towns. Decade by decade the climate has edged up, 0.8° above 1901–2000. Keep the boiler serviced for the months from November to March, which average under 50°.
A year in Gilliam at a glance
Each month’s typical high and low, and what it brings.
What stands out about Gilliam’s climate
Compared with towns across the U.S., with Gilliam’s place in Missouri beside it.
What a year in Gilliam feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 196 frost-free days a year
In half of years the last 32° night comes by April 10 and the first by October 24. Frost and day counts come from NOAA’s station at Marshall, MO, 14 miles from the town’s center, at about the same height.
The 2023 USDA map puts Gilliam’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −4°. 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 8 inches of snow a winter
Snow, measured at Marshall, MO, falls mostly in January. Precipitation (rain plus melted snow) adds up to 41 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 106 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Gilliam
80% of the work is heating. Months averaging under 55° run from November 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 Marshall, MO.
Living with Gilliam’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
196 frost-free days in zone 6b. The last frost comes by Apr 10 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 24.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October.
Parks & trails →Of the yearly building losses FEMA expects in Gilliam from natural hazards, river flooding is the largest share (48%); heat waves, cold waves, winter storms and ice storms together are 28%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Gilliam and similar climates
TownRatings has no climate map of the towns around Gilliam yet.
Climates most like Gilliam’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 |
|---|---|---|---|---|
| Gilliam, MO | 20° | 88° | 41" | 8.1" |
| Godfrey, IL | 23° | 88° | 42" | 9.0" |
| Hamilton, OH | 22° | 87° | 43" | 9.7" |
| Terre Haute, IN | 21° | 87° | 43" | 15" |
| Flatwoods, KY | 24° | 87° | 44" | 6.6" |
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 Gilliam averaged 0.8° warmer than the 1900s. The biggest change is in December (+1.9°).
A smaller shift than in 90% 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 Gilliam compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Gilliam’s place among Missouri’s.
Gilliam weather by month
Highs, lows and precipitation from NOAA’s grid at Gilliam’s center; snow, wet days and snow on the ground from Marshall, MO. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 37° | 20° | 1.5" | 3.0" | 7 | 3 | 22° – 39° |
| February | 43° | 24° | 1.9" | 2.2" | 7 | 3 | 23° – 44° |
| March | 54° | 34° | 2.9" | 0.9" | 10 | 1 | 36° – 58° |
| April | 65° | 44° | 4.3" | 0.0" | 11 | 0 | 47° – 61° |
| May | 75° | 54° | 5.1" | 0.0" | 12 | 0 | 59° – 73° |
| June | 83° | 63° | 5.1" | 0.0" | 11 | 0 | 69° – 78° |
| July | 88° | 67° | 4.7" | 0.0" | 9 | 0 | 73° – 84° |
| August | 86° | 65° | 3.9" | 0.0" | 8 | 0 | 69° – 81° |
| September | 79° | 57° | 4.0" | 0.0" | 8 | 0 | 62° – 74° |
| October | 67° | 45° | 3.4" | 0.1" | 9 | 0 | 50° – 62° |
| November | 53° | 34° | 2.6" | 0.3" | 8 | 0 | 36° – 51° |
| December | 41° | 25° | 1.9" | 1.6" | 7 | 1 | 18° – 41° |
| Year | 64° | 44° | 41.1" | 8.1" | 106 | 8 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 18° to 41°. June is the most reliable, staying within 8°.
Where Gilliam’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 Gilliam’s center.
- Snow: Marshall, MO.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Marshall, MO, 14 miles from the town’s center, at about the same height; 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 Gilliam’s climate
What is the weather like in Gilliam?
A typical July afternoon reaches 88°, a January night drops to 20°, and about 8 inches of snow falls in a normal winter. Colder January nights than 58% of U.S. towns; hotter July afternoons than 65% of U.S. towns.
How cold does it get in Gilliam in winter?
January nights average 20°. About 116 nights a year reach 32° or below and 4 reach 0° or below. In the coldest January of the last 30 years the month averaged 22°.
How much snow does Gilliam get?
About 8.1 inches in a normal winter at Marshall, MO, most of it in January, with snow on the ground about 8 days a year.
How hot does it get in Gilliam?
July, with a typical high of 88° and a low of 67°. About 34 days a year reach 90° and 2 reach 100° (Marshall, MO).
When is the first and last frost in Gilliam?
In half of years the last spring frost (32°) comes by April 10 and the first fall frost by October 24, about 196 frost-free days, at Marshall, MO.
What growing zone is Gilliam in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −4°.
What is the best time of year to visit Gilliam?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Gilliam getting warmer?
Yes: 1991–2020 averaged 0.8° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 90% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Gilliam.
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.