Hardly any U.S. towns collect less precipitation than Castleford: 9 inches a year
Peak summer warmth arrives in July, with afternoons near 90°. Summer afternoons here are warmer than in 77% of U.S. towns. Warming shows here too: 1.2° more than in 1901–2000, led by January. The frost-free window for a garden runs roughly May 17 to September 29.
A year in Castleford at a glance
Each month’s typical high and low, and what it brings.
What stands out about Castleford’s climate
Compared with towns across the U.S., with Castleford’s place in Idaho beside it.
What a year in Castleford feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 132 frost-free days a year
In half of years the last 32° night comes by May 17 and the first by September 29. Frost and day counts come from NOAA’s station at Castleford 2 N, ID, 2.1 miles from the town’s center, at about the same height.
The 2023 USDA map puts Castleford’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −1°. 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 9 inches of rain a year
May is the wettest month and July the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Castleford
94% 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 Castleford 2 N, ID.
Living with Castleford’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
132 frost-free days in zone 6b. The last frost comes by May 17 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 29.
Months with highs of 62–84° and lows of 40° or more: May, June and September.
Parks & trails →Of the yearly building losses FEMA expects in Castleford from natural hazards, river flooding is the largest share (42%); heat waves, cold waves, winter storms and ice storms together are 13%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Castleford and similar climates
TownRatings has no climate map of the towns around Castleford 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 Castleford averaged 1.2° warmer than the 1900s. The biggest change is in January (+2.9°).
A smaller shift than in 64% 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 Castleford compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Castleford’s place among Idaho’s.
Castleford weather by month
Highs, lows and precipitation from NOAA’s grid at Castleford’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 39° | 22° | 0.9" | 20° – 37° |
| February | 44° | 25° | 0.6" | 26° – 42° |
| March | 54° | 30° | 0.9" | 37° – 48° |
| April | 60° | 35° | 1.1" | 43° – 52° |
| May | 70° | 42° | 1.3" | 51° – 62° |
| June | 79° | 50° | 0.7" | 60° – 73° |
| July | 90° | 57° | 0.2" | 64° – 79° |
| August | 88° | 55° | 0.2" | 66° – 75° |
| September | 78° | 47° | 0.5" | 59° – 66° |
| October | 64° | 36° | 0.7" | 41° – 57° |
| November | 49° | 27° | 0.7" | 31° – 45° |
| December | 39° | 22° | 1.0" | 25° – 36° |
| Year | 63° | 37° | 8.7" |
How much a month can swing
A normal is an average. January swings the most: from 1991 to 2020 its average ranged from 20° to 37°. September is the most reliable, staying within 7°.
Where Castleford’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 Castleford’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Castleford 2 N, ID, 2.1 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 Castleford’s climate
What is the weather like in Castleford?
A typical July afternoon reaches 90°, a January night drops to 22°. Milder January nights than 50% of U.S. towns; hotter July afternoons than 77% of U.S. towns.
How cold does it get in Castleford in winter?
December nights average 22°. About 146 nights a year reach 32° or below and 2 reach 0° or below. In the coldest December of the last 30 years the month averaged 25°.
How hot does it get in Castleford?
July, with a typical high of 90° and a low of 57°. About 34 days a year reach 90° (Castleford 2 N, ID).
When is the first and last frost in Castleford?
In half of years the last spring frost (32°) comes by May 17 and the first fall frost by September 29, about 132 frost-free days, at Castleford 2 N, ID.
What growing zone is Castleford in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −1°.
What is the best time of year to visit Castleford?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Castleford getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 64% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Castleford.
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.