Photo: BroMcjoe · CC BY-SA 4.0Spencer is drier than 93% of U.S. towns: 15 inches of precipitation a year
In July the day’s top temperature is typically 82°. Seasons differ by 71°, from the coldest nights to the warmest afternoons. In January, nights here are colder than in 93% of U.S. towns. Central heating does most of its work from October to May, in months below 50° on average.
A year in Spencer at a glance
Each month’s typical high and low, and what it brings.
What stands out about Spencer’s climate
Compared with towns across the U.S., with Spencer’s place in Idaho beside it.
What a year in Spencer feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 106 frost-free days a year
In half of years the last 32° night comes by June 5 and the first by September 20. Frost and day counts come from NOAA’s station at Small 6n, ID, 12 miles from the town’s center, 300 ft lower.
The 2023 USDA map puts Spencer’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −15°. 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 15 inches of rain a year
May is the wettest month and August the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Spencer
98% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from September 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 Small 6n, ID.
Living with Spencer’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
106 frost-free days in zone 5a. The last frost comes by Jun 5 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 20.
Months with highs of 62–84° and lows of 40° or more: June, July and August.
Parks & trails →Of the yearly building losses FEMA expects in Spencer from natural hazards, river flooding is the largest share (35%); heat waves, cold waves, winter storms and ice storms together are 12%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Spencer and similar climates
TownRatings has no climate map of the towns around Spencer 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 Spencer averaged 1.2° warmer than the 1900s. The biggest change is in March (+3.6°).
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 Spencer compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Spencer’s place among Idaho’s.
Spencer weather by month
Highs, lows and precipitation from NOAA’s grid at Spencer’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 27° | 10° | 1.0" | 13° – 26° |
| February | 31° | 12° | 0.9" | 16° – 30° |
| March | 41° | 21° | 1.0" | 23° – 38° |
| April | 51° | 28° | 1.4" | 32° – 45° |
| May | 62° | 36° | 2.2" | 43° – 54° |
| June | 71° | 43° | 1.9" | 51° – 63° |
| July | 82° | 49° | 0.9" | 55° – 73° |
| August | 80° | 47° | 0.8" | 58° – 68° |
| September | 70° | 39° | 1.2" | 51° – 60° |
| October | 54° | 29° | 1.3" | 32° – 47° |
| November | 38° | 19° | 0.9" | 21° – 37° |
| December | 27° | 11° | 1.2" | 13° – 24° |
| Year | 53° | 29° | 14.7" |
How much a month can swing
A normal is an average. July swings the most: from 1991 to 2020 its average ranged from 55° to 73°. September is the most reliable, staying within 10°.
Where Spencer’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 Spencer’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Small 6n, ID, 12 miles from the town’s center, 300 ft lower; 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 Spencer’s climate
What is the weather like in Spencer?
A typical July afternoon reaches 82°, a January night drops to 10°. Colder January nights than 93% of U.S. towns; cooler July afternoons than 83% of U.S. towns.
How cold does it get in Spencer in winter?
January nights average 10°. About 191 nights a year reach 32° or below and 11 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How hot does it get in Spencer?
July, with a typical high of 82° and a low of 49°. About 10 days a year reach 90° (Small 6n, ID).
When is the first and last frost in Spencer?
In half of years the last spring frost (32°) comes by June 5 and the first fall frost by September 20, about 106 frost-free days, at Small 6n, ID.
What growing zone is Spencer in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −15°.
What is the best time of year to visit Spencer?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July and August. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Spencer 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 Spencer.
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.