Charlo, Montana Weather
Thunder retreats as the monsoon dies. Day 93 of summer. Read this microseason across nine climate regions →
Charlo weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 1:00 AM MDT · Open-Meteo
- TodaySep 21Clear——80°47°—
- TuesdaySep 22Clear——81°54°+1°
- WednesdaySep 23Overcast——75°50°-6°
- ThursdaySep 24Overcast——85°49°+10°
- FridaySep 25Light Showers26%0.10″63°46°-22°
- SaturdaySep 26Overcast26%—62°40°-1°
- SundaySep 27Overcast11%—65°44°+3°
Air quality now AQI 40 · Good
AQI 40 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 7.8 µg/m³ (AQI 43) with a 0.80 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in stagnant air, not road dust.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 7.8 µg/m³ (AQI 43) with a 0.80 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in stagnant air, not road dust.
- PM2.5/PM10
- 0.80
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 5:36 PM
- Moonset
- 1:33 AM
- In sign
- ♑︎ Capricorn
Thunder retreats as the monsoon dies
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Charlo at a glance
- Today vs. normal: Today averages 64°F (high 80°F, low 47°F), 7°F above the 57°F normal for Sep 21
- Last frost: May 12 (1991–2020 median, NOAA station 15 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots
15-Day Forecast — Charlo
- Mon80°47°0%
- Tue81°54°8%
- Wed75°50°8%
- Thu85°49°5%
- Fri63°46°26%
- Sat62°40°26%
- Sun65°44°11%
- Mon68°41°15%
- Tue70°45°8%
- Wed72°49°10%
- Thu79°56°9%
- Fri80°53°16%
- Sat59°44°20%
- Sun58°44°19%
- Mon60°40°19%
Forecast data from Open-Meteo (CC BY 4.0).
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 2) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, and carrots.
SPC Convective Outlook
Storm Prediction Center — Charlo
SPC includes Charlo in the general thunderstorm area tomorrow — no severe risk, but storms are possible.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook.
Sun & seasons in Charlo
Charlo sits in Lake County, where the year’s longest day runs 15h 58m of daylight and its shortest just 8h 27m — a swing of +7h 31m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Billings, the state’s largest city, lies about 290 miles to the ESE. The nearest town Charlo tracks is Bull Lake, roughly 95 miles to the NW.
Air quality in Charlo
Air quality in Charlo’s county has trended dirtier since 2020; its cleanest year on record was 2020 (median AQI 7).
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes | spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | tomatoes, peppers, beans, squash, fall brassicas, carrots | lettuce, peas, spinach |
| August | garlic (overwinter) | peas, tomatoes, peppers, beans, summer squash, garlic |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| October | — | fall brassicas, carrots |
A year in weather
Charlo peaks at about 69°F in July and bottoms near 30°F in December; June brings the heaviest rain (2.6 inches) and December the least (0.9 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 30° | 0.9″ | 3 |
| February | 31° | 1.1″ | 3 |
| March | 39° | 0.9″ | 3 |
| April | 47° | 1.8″ | 4 |
| May | 55° | 2.3″ | 7 |
| June | 61° | 2.6″ | 7 |
| July | 69° | 1.0″ | 3 |
| August | 68° | 1.2″ | 3 |
| September | 59° | 1.5″ | 3 |
| October | 47° | 1.3″ | 4 |
| November | 36° | 1.1″ | 3 |
| December | 30° | 0.9″ | 3 |
Regional context
Similar climates Kicking Horse, MT, Ronan, MT, St. Ignatius, MT
By the nearest station's NOAA NCEI 1991-2020 normals, Charlo sees 30°F Januarys and 69°F Julys, a 39°F range, plus around 16.7 inches of precipitation across 46 days.
Summer convection drives Charlo's precipitation: June logs 2.6 inches on 6.8 rainy days, against December's 0.9 inches on 2.6 — warm-season storms carry Charlo's moisture. That puts Charlo in a summer-convective cohort with places like Kicking Horse, MT, Ronan, MT and St. Ignatius, MT.
Charlo's growing window opens around May 12, once Charlo's overnight lows stop freezing — sow kale, peas, spinach, and parsnips. In Charlo, warm-season transplants — tomatoes, peppers, basil — wait two weeks past Charlo's frost date. Charlo's window closes around October 2 as Charlo's overnight lows return below freezing. In about half of years, Charlo's last freeze comes after May 12.
Similar climates: Kicking Horse, MT, Ronan, MT, St. Ignatius, MT, Old Agency, MT, Ravalli, MT.
Frequently asked
- When does it freeze in Charlo?
- Frost typically leaves Charlo by May 12 and returns to Charlo near October 2.
- What is the rainy season in Charlo?
- Rainfall in Charlo peaks in June near 2.6 inches, out of about 17 inches annually.
- What is the warmest month in Charlo?
- The warmest stretch in Charlo comes in July, around 69°F on average.
- What is the coldest month in Charlo?
- On average December is the chilliest month in Charlo, about 30°F.
- When can I start a vegetable garden in Charlo?
- Frost-hardy sowings begin at May 12 in Charlo; warm-season starts follow two weeks on.
- How many rainy days does Charlo get?
- Charlo averages about 46 days with measurable rain or snow each year.
- What hardiness zone is Charlo?
- Charlo's hardiness zone tracks its winter low; with December near 30°F, check the USDA ZIP map for the exact zone.
- What is the 10-day forecast for Charlo?
- Charlo's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Charlo?
- See this week's day-by-day rain chances for Charlo in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Charlo?
- Current conditions for Charlo and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Charlo forecast updated?
- The Charlo forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Charlo?
- Today's sunrise and sunset times for Charlo are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Charlo?
- The next few days in Charlo's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Charlo sits at 47.4°N; its climate zone is cold semi-arid (Köppen approximation).
ZIP codes in Charlo
- 59824