Winter nights in Fairfield are colder than in 94% of U.S. towns
Midsummer highs settle at about 84°. The gap between a January night and a July afternoon is 75°. By precipitation alone, it ranks drier than 94% of U.S. towns. The frost-free window for a garden runs roughly June 8 to September 14.
A year in Fairfield at a glance
Each month’s typical high and low, and what it brings.
What stands out about Fairfield’s climate
Compared with towns across the U.S., with Fairfield’s place in Idaho beside it.
What a year in Fairfield feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 97 frost-free days a year
In half of years the last 32° night comes by June 8 and the first by September 14. Frost and day counts come from NOAA’s station at Fairfield Rs, ID, 0.7 miles from the town’s center, at about the same height.
The 2023 USDA map puts Fairfield’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −19°. 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 14 inches of rain a year
December is the wettest month and August the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Fairfield
98% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Fairfield Rs, ID.
Living with Fairfield’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
97 frost-free days in zone 5a. The last frost comes by Jun 8 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 14.
Months with highs of 62–84° and lows of 40° or more: June and August.
Parks & trails →Of the yearly building losses FEMA expects in Fairfield from natural hazards, avalanches are the largest share (66%); heat waves, cold waves, winter storms and ice storms together are 2%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Fairfield and similar climates
TownRatings has no climate map of the towns around Fairfield yet.
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 Fairfield averaged 1.5° warmer than the 1900s. The biggest change is in January (+2.9°).
A bigger shift than in 60% 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 Fairfield compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Fairfield’s place among Idaho’s.
Fairfield weather by month
Highs, lows and precipitation from NOAA’s grid at Fairfield’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 31° | 9° | 2.1" | 11° – 28° |
| February | 35° | 12° | 1.4" | 18° – 33° |
| March | 44° | 22° | 1.4" | 28° – 40° |
| April | 54° | 29° | 1.0" | 36° – 48° |
| May | 65° | 36° | 1.4" | 44° – 55° |
| June | 74° | 42° | 0.7" | 53° – 64° |
| July | 84° | 48° | 0.3" | 56° – 72° |
| August | 83° | 46° | 0.3" | 59° – 68° |
| September | 74° | 38° | 0.6" | 52° – 60° |
| October | 59° | 29° | 1.1" | 37° – 50° |
| November | 43° | 20° | 1.5" | 21° – 38° |
| December | 31° | 10° | 2.5" | 15° – 27° |
| Year | 56° | 29° | 14.1" |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 21° to 38°. September is the most reliable, staying within 8°.
Where Fairfield’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 Fairfield’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Fairfield Rs, ID, 0.7 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 Fairfield’s climate
What is the weather like in Fairfield?
A typical July afternoon reaches 84°, a January night drops to 9°. Colder January nights than 94% of U.S. towns; cooler July afternoons than 57% of U.S. towns.
How cold does it get in Fairfield in winter?
January nights average 9°. About 204 nights a year reach 32° or below and 28 reach 0° or below. In the coldest January of the last 30 years the month averaged 11°.
How hot does it get in Fairfield?
July, with a typical high of 84° and a low of 48°. About 19 days a year reach 90° (Fairfield Rs, ID).
When is the first and last frost in Fairfield?
In half of years the last spring frost (32°) comes by June 8 and the first fall frost by September 14, about 97 frost-free days, at Fairfield Rs, ID.
What growing zone is Fairfield in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −19°.
What is the best time of year to visit Fairfield?
By one simple rule (highs of 62–84° and lows of 40° or more), June and August. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Fairfield getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 60% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Fairfield.
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.