St. Peter's Catholic Church · Photo: Jim Roberts · CC BY-SA 4.0For weather, Rensselaer is about as ordinary as U.S. towns get
Sunny July days climb to about 86°. In January, nights here are colder than in 65% of U.S. towns. December has warmed most since 1901–2000, part of a 0.6° rise. The heating season runs November to March: each of those months averages under 50°.
A year in Rensselaer at a glance
Each month’s typical high and low, and what it brings.
What stands out about Rensselaer’s climate
Compared with towns across the U.S., with Rensselaer’s place in Missouri beside it.
What a year in Rensselaer feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 199 frost-free days a year
In half of years the last 32° night comes by April 10 and the first by October 27. Frost and day counts come from NOAA’s station at Hannibal Wtr Wks, MO, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Rensselaer’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −6°. 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 13 inches of snow a winter
Snow, measured at Palmyra, MO, falls mostly in January, February and December. Precipitation (rain plus melted snow) adds up to 40 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 93 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Rensselaer
82% 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 Hannibal Wtr Wks, MO.
Living with Rensselaer’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
199 frost-free days in zone 6a. 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 27.
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 Rensselaer from natural hazards, river flooding is the largest share (48%); heat waves, cold waves, winter storms and ice storms together are 27%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Rensselaer and similar climates
TownRatings has no climate map of the towns around Rensselaer yet.
Climates most like Rensselaer’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 |
|---|---|---|---|---|
| Rensselaer, MO | 19° | 86° | 40" | 13" |
| Mattoon, IL | 20° | 86° | 41" | 15" |
| Dayton, OH | 22° | 86° | 41" | 12" |
| Terre Haute, IN | 21° | 87° | 43" | 15" |
| Spring Hill, KS | 21° | 88° | 40" | 14" |
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 Rensselaer averaged 0.6° warmer than the 1900s. The biggest change is in December (+1.9°).
A smaller shift than in 97% 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 Rensselaer compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Rensselaer’s place among Missouri’s.
Rensselaer weather by month
Highs, lows and precipitation from NOAA’s grid at Rensselaer’s center; snow, wet days and snow on the ground from Palmyra, MO. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 35° | 19° | 1.9" | 3.4" | 6 | 21° – 39° |
| February | 41° | 23° | 1.9" | 3.1" | 6 | 20° – 42° |
| March | 52° | 32° | 2.8" | 1.6" | 8 | 34° – 56° |
| April | 64° | 43° | 4.1" | 0.6" | 10 | 46° – 60° |
| May | 74° | 53° | 5.1" | 0.0" | 11 | 59° – 72° |
| June | 83° | 63° | 4.7" | 0.0" | 9 | 69° – 77° |
| July | 86° | 67° | 4.1" | 0.0" | 8 | 71° – 83° |
| August | 85° | 64° | 3.7" | 0.0" | 8 | 69° – 80° |
| September | 78° | 57° | 3.6" | 0.0" | 7 | 62° – 74° |
| October | 66° | 45° | 3.1" | 0.0" | 8 | 49° – 61° |
| November | 52° | 34° | 2.7" | 0.7" | 7 | 36° – 52° |
| December | 40° | 24° | 2.0" | 3.1" | 7 | 17° – 41° |
| Year | 63° | 44° | 39.7" | 12.5" | 93 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 17° to 41°. June is the most reliable, staying within 8°.
Where Rensselaer’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 Rensselaer’s center.
- Snow: Palmyra, MO.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Hannibal Wtr Wks, MO, 10 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 Rensselaer’s climate
What is the weather like in Rensselaer?
A typical July afternoon reaches 86°, a January night drops to 19°, and about 13 inches of snow falls in a normal winter. Colder January nights than 65% of U.S. towns; hotter July afternoons than 58% of U.S. towns.
How cold does it get in Rensselaer in winter?
January nights average 19°. About 114 nights a year reach 32° or below and 6 reach 0° or below. In the coldest January of the last 30 years the month averaged 21°.
How much snow does Rensselaer get?
About 13 inches in a normal winter at Palmyra, MO, most of it in January, February and December.
How hot does it get in Rensselaer?
July, with a typical high of 86° and a low of 67°. About 25 days a year reach 90° and 1 reach 100° (Hannibal Wtr Wks, MO).
When is the first and last frost in Rensselaer?
In half of years the last spring frost (32°) comes by April 10 and the first fall frost by October 27, about 199 frost-free days, at Hannibal Wtr Wks, MO.
What growing zone is Rensselaer in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −6°.
What is the best time of year to visit Rensselaer?
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 Rensselaer getting warmer?
Yes: 1991–2020 averaged 0.6° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 97% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Rensselaer.
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.