Potosi, Missouri climate: Normal weather by month, frost dates and records
Potosi's normal year runs from 21°F January nights to 86°F July afternoons, with 45.5 inches of precipitation and 12 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.6°C, January lows of −6°C, July highs of 30°C, 1,155 mm of precipitation a year.
- NOAA stationPotosi (4 mi SW)
- Station IDUSC00236826
- Location37.90°N 90.84°W
- Elevation1,105 ft (337 m)
- Population2,549
On October 23, the normal high in Potosi is 65°F and the normal low 44°F, and the chance of measurable rain or snow is 28%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Potosi.
- Jan 40° 21°
- Feb 45° 25°
- Mar 55° 34°
- Apr 66° 44°
- May 74° 54°
- Jun 82° 63°
- Jul 86° 67°
- Aug 85° 65°
- Sep 78° 57°
- Oct 68° 46°
- Nov 54° 35°
- Dec 43° 26°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Potosi each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 21°F. The most precipitation falls in May (5.29 in), the least in February (2.69 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 40°F | 21°F | 30.5°F | 2.84 | 3.6 | 7 | <1 | 26 | 9 h 50 min |
| February | 45°F | 25°F | 35.2°F | 2.69 | 2.9 | 8 | <1 | 21 | 10 h 50 min |
| March | 55°F | 34°F | 44.3°F | 4.09 | 1.9 | 11 | <1 | 15 | 11 h 50 min |
| April | 66°F | 44°F | 55.3°F | 5.11 | 0.0 | 11 | <1 | 4 | 13 h 10 min |
| May | 74°F | 54°F | 64.1°F | 5.29 | 0.0 | 13 | 1 | <1 | 14 h 10 min |
| June | 82°F | 63°F | 72.3°F | 4.15 | 0.0 | 10 | 3 | <1 | 14 h 50 min |
| July | 86°F | 67°F | 76.3°F | 3.64 | 0.0 | 9 | 9 | <1 | 14 h 30 min |
| August | 85°F | 65°F | 75.1°F | 4.00 | 0.0 | 9 | 8 | <1 | 13 h 40 min |
| September | 78°F | 57°F | 67.4°F | 3.89 | 0.0 | 7 | 2 | <1 | 12 h 30 min |
| October | 68°F | 46°F | 56.9°F | 3.07 | 0.0 | 8 | <1 | 2 | 11 h 20 min |
| November | 54°F | 35°F | 44.7°F | 3.72 | 0.7 | 8 | <1 | 12 | 10 h 10 min |
| December | 43°F | 26°F | 34.9°F | 2.97 | 2.4 | 9 | <1 | 23 | 9 h 30 min |
| Year (annual) | 65°F | 45°F | 54.7°F | 45.46 | 11.5 | 109 | 23 | 103 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −6°C | −0.8°C | 72 mm | 9 cm |
| February | 7°C | −4°C | 1.8°C | 68 mm | 7 cm |
| March | 13°C | 1°C | 6.8°C | 104 mm | 5 cm |
| April | 19°C | 7°C | 12.9°C | 130 mm | 0 cm |
| May | 23°C | 12°C | 17.8°C | 134 mm | 0 cm |
| June | 28°C | 17°C | 22.4°C | 105 mm | 0 cm |
| July | 30°C | 19°C | 24.6°C | 92 mm | 0 cm |
| August | 30°C | 18°C | 23.9°C | 102 mm | 0 cm |
| September | 25°C | 14°C | 19.7°C | 99 mm | 0 cm |
| October | 20°C | 8°C | 13.8°C | 78 mm | 0 cm |
| November | 12°C | 2°C | 7.1°C | 94 mm | 2 cm |
| December | 6°C | −3°C | 1.6°C | 75 mm | 6 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00236826; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Potosi?
Normal highs sit between 65°F and 85°F in April, May, June, September and October. Of those, September has the fewest days with rain (7).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00236826.
When is the last frost in Potosi?
In Potosi, the last spring frost (32°F) comes after April 11 in half of years and after April 30 in one year in ten; the first autumn frost comes before October 28 in half of years and before October 14 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 111 year in 10 after April 30; 9 in 10 after March 26
- First autumn frost, half of years before
- October 281 year in 10 before October 14; 9 in 10 before November 8
NOAA puts the median frost-free season at 198 days, and the season without a hard freeze (28°F) at 220 days.
A hard freeze (28°F) comes after March 31 in half of springs and before November 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Potosi in zone 6b in ZIP code 63660, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Potosi's NOAA station is in zone 6b: the coldest night of a typical year reaches −3°F (17 complete years).
Frost dates for every NOAA station in Missouri · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00236826; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Potosi?
In a normal year in Potosi, 23 days a year reach 90°F (1 of them 100°F or more), 103 nights fall to 32°F or colder and 109 days bring measurable precipitation.
- Days at 90°F or more
- 23a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 103a normal year
- Days that stay below freezing
- 25high of 32°F or less
- Days with 0.01 inch of precipitation
- 109a normal year
- Days with 1 inch of snow or more
- 5a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00236826.
How sunny is Potosi?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Potosi, 4.3 kWh per square metre a day. June is the sunniest month (82%) and December the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 2.2 |
| February | 66% | 2.9 |
| March | 68% | 3.9 |
| April | 72% | 5.1 |
| May | 74% | 5.7 |
| June | 82% | 6.5 |
| July | 82% | 6.3 |
| August | 81% | 5.6 |
| September | 81% | 4.8 |
| October | 76% | 3.5 |
| November | 73% | 2.5 |
| December | 66% | 1.9 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Potosi need?
A normal year in Potosi brings 4,900 heating degree days, 9% fewer than the median U.S. place (5,373), and 1,196 cooling degree days, 32% more than the median (908). Six months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,879 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,069 | 0 |
| February | 833 | 0 |
| March | 646 | 5 |
| April | 317 | 26 |
| May | 119 | 89 |
| June | 14 | 234 |
| July | 2 | 354 |
| August | 4 | 317 |
| September | 68 | 138 |
| October | 283 | 31 |
| November | 611 | 2 |
| December | 933 | 0 |
| Year (annual) | 4,900 | 1,196 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00236826. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Potosi been warmer than normal lately?
2024 averaged 57.9°F, 3.2°F above the 1991-2020 normal of 54.7°F.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2024 | 57.9°F | +3.2°F | 57.84 | – |
Source: observed years: ACIS, station USC00236826. A year counts only with all twelve months complete.
How does Potosi's climate compare?
Potosi is warmer than 53 of the other 133 places with their own NOAA record in Missouri, and wetter than 82. Across the 7,247 U.S. stations with normals, its annual mean of 54.7°F is warmer than 59%.
In the Köppen classification computed from these normals, Potosi is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Potosi share this climate record?
5 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Terre du Lac, MO2,460 people · 12 mi E
- Viburnum, MO658 people · 20 mi SW
- Irondale, MO368 people · 10 mi SE
- Mineral Point, MO234 people · 7 mi NE
- Caledonia, MO132 people · 10 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Potosi's climate
What is the coldest month in Potosi?
January, with a normal high of 40°F and a normal low of 21°F. The warmest is July (86°F by day, 67°F at night).
Does it snow in Potosi?
Yes: 12 inches in a normal year, falling on 9 days with 0.1 inch or more, the most in January (3.6 inches).
What is the rainiest month in Potosi?
May, with 5.29 in of precipitation in a normal year; the driest is February with 2.69 in.
What plant hardiness zone is Potosi in?
The USDA's 2023 map puts Potosi in zone 6b in ZIP code 63660, the nearest ZIP area. By the same method at Potosi's NOAA station, the coldest night of a typical year reaches −3°F (17 years, 1991-2020): zone 6b.
How late can frost come in Potosi?
In half of years the last 32°F night comes after April 11; in one year in ten it comes after April 30. Waiting until April 30 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Missouri climateThe statewide normals and every place in the state
- Farmington, MO25 miles from this station, 56.1°F a year
- Steelville, MO30 miles from this station, 53.4°F a year
- Festus, MO34 miles from this station, 55.7°F a year
- Fredericktown, MO37 miles from this station, 54.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made