Arco, ID Climate: Temperature & Rain by Month
Explore NOAA NCEI's 1991–2020 climate normals → and a clearly labeled PlainClimate comfort calculation
30-year climate normals (1991-2020) from Arco's primary NOAA station, ARCO 17 SW - 2 stations mapped to the area.
The climate verdict for Arco
Dryness leads the climate profile for Arco, Idaho, with 15.5 inches of precipitation a year. NOAA records an annual average of 43°F. At 40/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 6% of scores.
- 43°F
- annual average temperature (NOAA normal)
- 40/100
- comfort score, above 6% of station-mapped location scores
- 15.5"
- precipitation, annual total
- 130 days
- growing season, frost-free days
Arco: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00004126 · Arco, ID 43°F mean · 15.5" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-WIDE · COMF-LOW · LOAD-HEAT · STN-MULTI · BOOK-FULL
- TEMP-COOL 43°F
- RANK-COOL #823
- PHOTO-FINISH ≈ Northwood
- PRCP-DRY 15.5"
- SWING-WIDE 50°F
- COMF-LOW 40/100
- LOAD-HEAT 8,331 HDD
- STN-MULTI USW00004126
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Northwood, IA (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every ID station list.
- Arco (this station) 43°F
- Cold Stephenson, MI 43°F
- Hot Lincoln Sanitar…, ME 43°F
- Near Northwood, IA 43°F
- Near Hayward Ranger…, WI 43°F
Climate Living Index · Arco
Arco: 20/100 · grade F
Arco publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Arco, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 15.5 in · 19.5 from 35 in | 30/100 · F |
| Normal heat + freeze calendar | 182 calendar days | 24/100 · F |
| Annual temperature balance | 43.0°F · 24.5° from 67.5°F | 13/100 · F |
| Frost-free season | 130 days/year | 12/100 · F |
Arco · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Arco is a continental Köppen climate: Dsb
Coldest-month mean 20.1°F and warmest-month mean 69.6°F place this station in continental, dry-summer, warm summer climates (Dsb). Class Dsb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, dry-summer, warm summer.
- Köppen code
- Dsb
- Group
- Continental
- Warmest month
- 69.6°F
- Coldest month
- 20.1°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Arco sits across the climate record
Three NOAA fields for Arco's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 88%
- Among 6,861 stations, Arco sits in the cooler third of annual means.
- Annual precipitation
- Drier than 81%
- Arco's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- Wider than 79%
- Warmest-to-coldest month gap for Arco is large versus 6,861 complete station-years.
How Arco compares across U.S. station-mapped locations
Arco's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
40 6th percentile score exceeds 6% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 27°F (-3°C) | 13°F (-11°C) | 20°F (-7°C) | 2.4" | N/A | 31.0 | 0.0 |
| February | 30°F (-1°C) | 15°F (-9°C) | 22°F (-5°C) | 1.2" | N/A | 27.7 | 0.0 |
| March | 40°F (4°C) | 23°F (-5°C) | 32°F (0°C) | 1.9" | N/A | 26.6 | 0.0 |
| April | 51°F (11°C) | 31°F (-1°C) | 41°F (5°C) | 1.1" | N/A | 17.8 | 0.0 |
| May | 62°F (17°C) | 40°F (4°C) | 51°F (11°C) | 1.6" | N/A | 5.8 | 0.0 |
| June | 72°F (22°C) | 46°F (8°C) | 59°F (15°C) | 1.2" | N/A | 0.9 | 0.8 |
| July | 83°F (29°C) | 56°F (13°C) | 70°F (21°C) | 0.3" | N/A | 0.0 | 8.1 |
| August | 82°F (28°C) | 54°F (12°C) | 68°F (20°C) | 0.5" | N/A | 0.0 | 3.8 |
| September | 71°F (22°C) | 45°F (7°C) | 58°F (15°C) | 0.7" | N/A | 1.1 | 0.2 |
| October | 56°F (13°C) | 34°F (1°C) | 45°F (7°C) | 1.2" | N/A | 13.5 | 0.0 |
| November | 39°F (4°C) | 22°F (-6°C) | 31°F (-1°C) | 1.2" | N/A | 26.2 | 0.0 |
| December | 27°F (-3°C) | 14°F (-10°C) | 20°F (-6°C) | 2.0" | N/A | 30.7 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 85°F around July 24, short of 90°F on every date, while 182 dates carry a normal low at or below freezing, the coldest 12°F near December 25.
The freezing stretch
The normal low stays at or below 32°F into April 19, then returns to freezing around October 21, covering 182 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is December 23, when 38% of years recorded at least a hundredth of an inch. The driest is July 23 at 10%. Summed across the calendar, that is about 98 wet dates a year.
The widest day
July 11 carries the biggest normal gap between afternoon and dawn, 28°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Arco.
Where Arco Stands Nationally
Freezing is routine here by normals standards — the normal low reaches 32°F or colder on about 182 nights a year, more than most ranked stations.
A drier-than-most normal water year — around 16 inches, below what four out of five ranked stations collect.
Arco earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall and snowfall
11.1 days with precipitation
8.2 days with precipitation
11.3 days with precipitation
9.6 days with precipitation
11.3 days with precipitation
7.3 days with precipitation
2.9 days with precipitation
3.7 days with precipitation
4.7 days with precipitation
6.6 days with precipitation
9.2 days with precipitation
11.9 days with precipitation
Arco's wet season runs through the cold months
December, January and February carry 36% of the year's precipitation here, while June through August contribute 14%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows a wide 49.5°F gap between its warmest and coldest month.
- Wettest month
- January, 2.4"
- Driest month
- July, 0.3"
- Wettest three months
- January, December, March (41% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
Arco is dry, and what does fall arrives gently
Only about 98 days a year record measurable precipitation here, 27% of the calendar, and they carry 15.5" between them. At roughly 0.16 inches on an average wet day, this is not the damp drizzle of a marine climate; it is an arid record in which precipitation is both uncommon and light when it appears.
The wettest month by count is December at about 12 wet days; the driest is July at about 3.
A low per-event average in a dry record is a statement about typical days only. Arid regions can still take a large share of a year's total from a single convective storm, which a normal cannot show.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, not the extremes within it.
Frost Dates & Growing Season
First Fall Freeze
October 1
50% probability date
Last Spring Freeze
May 24
50% probability date
Growing Season
130 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
8,331
Higher = more heating needed
Cooling Degree Days
357
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside ID closest to Arco on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (43°F here).
- Browns Valley, MN 43°F · 0.0°F off
- Estes Park, CO 43°F · 0.0°F off
- Fife Lake, MI 43°F · 0.0°F off
- Gaylord, MI 43°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (15.5" here), excluding temperature-peer places.
- Lindrith, NM 15.5" · 0.0" off
- Melstone, MT 15.5" · 0.0" off
- Denio, NV 15.5" · 0.0" off
- Sidney, MT 15.5" · 0.0" off
Data-derived climate profile
How Arco's climate pattern fits together
heating led · dry · mid swing
Arco's energy balance leans toward cold weather: 8,331 annual heating degree days against 357 for cooling. Its 49.5°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 130 days are frost-free in a normal year. That short interval is consistent with the cold-season signal, but the measure does not predict the exact first or last freeze in any one year.
July and January mark the typical warm and cold ends of the calendar in Arco's middle-range seasonal profile. The measured spread is 49.5°F. The annual average is 43°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Arco's cold-season load does not imply a wet climate. Annual precipitation is 15.5 inches, which places the station in PlainClimate's dry range. Snowfall is not added to the interpretation because its annual value is missing. The snowfall and rainfall fields should be read separately rather than inferred from temperature.
These labels group NOAA 1991-2020 normals from Arco's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Arco, not an official NOAA class or a year-ahead forecast.
Questions about Arco's climate
How much rain does Arco get? ▼
How cold does Arco get in winter? ▼
How much energy does heating and cooling require in Arco? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Arco's primary station: ARCO 17 SW (USW00004126). 2 NOAA stations are mapped to the Arco area; the primary station's record is used for consistency. For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 1603160). Match rule for Arco: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Arco comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.