Photo: Dennisyerger84 · CC BY-SA 3.0Winter nights in Merrillville are colder than in 77% of U.S. towns
Sunny July days climb to about 83°. Only 67° separates winter nights from summer afternoons. In July, afternoons here are cooler than in 66% of U.S. towns. Garden chairs stay out from May to October, the months with highs of 64–83°.
A year in Merrillville at a glance
Each month’s typical high and low, and what it brings.
What stands out about Merrillville’s climate
Compared with towns across the U.S., with Merrillville’s place in Indiana beside it.
What a year in Merrillville feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 185 frost-free days a year
In half of years the last 32° night comes by April 22 and the first by October 25. Frost and day counts come from NOAA’s station at Valparaiso Wtr Wks, IN, 15 miles from the town’s center, 130 ft higher.
The 2023 USDA map puts Merrillville’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −9°. 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 27 inches of snow a winter
Snow, measured at Crown Pt 1n, IN, falls mostly in January. Precipitation (rain plus melted snow) adds up to 39 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 112 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Merrillville
89% 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 Valparaiso Wtr Wks, IN.
Living with Merrillville’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
185 frost-free days in zone 6a. The last frost comes by Apr 22 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 25.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 6.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Merrillville from natural hazards, river flooding is the largest share (43%); heat waves, cold waves, winter storms and ice storms together are 30%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Merrillville and its neighbors
Every town next door is within a degree of Merrillville in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Merrillville’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 |
|---|---|---|---|---|
| Merrillville, IN | 17° | 83° | 39" | 27" |
| Bucyrus, OH | 18° | 83° | 40" | 23" |
| Galesburg, IL | 15° | 84° | 39" | 26" |
| Eldridge, IA | 14° | 84° | 38" | 29" |
| Sayre, PA | 17° | 84° | 37" | 35" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Merrillville averaged 1.2° warmer than the 1900s. The biggest change is in December (+2.5°).
A smaller shift than in 63% 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 Merrillville compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Merrillville’s place among Indiana’s.
Merrillville weather by month
Highs, lows and precipitation from NOAA’s grid at Merrillville’s center; snow, wet days and snow on the ground from Crown Pt 1n, IN. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 32° | 17° | 2.2" | 10.3" | 10 | 12 | 15° – 37° |
| February | 36° | 20° | 1.9" | 6.3" | 8 | 9 | 16° – 38° |
| March | 47° | 29° | 2.3" | 4.3" | 10 | 3 | 29° – 53° |
| April | 60° | 38° | 3.6" | 0.6" | 10 | 0 | 40° – 55° |
| May | 71° | 49° | 4.3" | 0.0" | 12 | 0 | 54° – 66° |
| June | 80° | 59° | 4.3" | 0.0" | 10 | 0 | 65° – 74° |
| July | 83° | 63° | 4.2" | 0.0" | 9 | 0 | 68° – 78° |
| August | 82° | 61° | 4.2" | 0.0" | 9 | 0 | 66° – 78° |
| September | 76° | 53° | 3.5" | 0.0" | 8 | 0 | 59° – 69° |
| October | 64° | 42° | 3.5" | 0.0" | 10 | 0 | 49° – 59° |
| November | 49° | 32° | 2.7" | 0.4" | 9 | 0 | 33° – 48° |
| December | 37° | 22° | 2.2" | 4.7" | 9 | 5 | 16° – 40° |
| Year | 60° | 40° | 38.9" | 26.6" | 112 | 29 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 16° to 40°. June is the most reliable, staying within 9°.
Where Merrillville’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 Merrillville’s center.
- Snow: Crown Pt 1n, IN.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Valparaiso Wtr Wks, IN, 15 miles from the town’s center, 130 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 Merrillville’s climate
What is the weather like in Merrillville?
A typical July afternoon reaches 83°, a January night drops to 17°, and about 27 inches of snow falls in a normal winter. Colder January nights than 77% of U.S. towns; cooler July afternoons than 66% of U.S. towns.
How cold does it get in Merrillville in winter?
January nights average 17°. About 124 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 15°.
How much snow does Merrillville get?
About 27 inches in a normal winter at Crown Pt 1n, IN, most of it in January, with snow on the ground about 29 days a year.
How hot does it get in Merrillville?
July, with a typical high of 83° and a low of 63°. About 9 days a year reach 90° (Valparaiso Wtr Wks, IN).
When is the first and last frost in Merrillville?
In half of years the last spring frost (32°) comes by April 22 and the first fall frost by October 25, about 185 frost-free days, at Valparaiso Wtr Wks, IN.
What growing zone is Merrillville in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −9°.
What is the best time of year to visit Merrillville?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Merrillville getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 63% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Merrillville.
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.