Sulphur, Oklahoma climate: Normal weather by month, frost dates and records
Sulphur's normal year runs from 28°F January nights to 93°F August afternoons, with 40.7 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 16.3°C, January lows of −2°C, August highs of 34°C, 1,033 mm of precipitation a year.
- NOAA stationSulphur 4 mi NNE Mesonet
- Station IDUSC00348570
- Location34.57°N 96.95°W
- Elevation1,049 ft (320 m)
- From the center5 miles
- Population4,844
On October 23, the normal high in Sulphur is 71°F and the normal low 47°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Sulphur.
- Jan 52° 28°
- Feb 56° 33°
- Mar 65° 41°
- Apr 72° 49°
- May 79° 59°
- Jun 87° 67°
- Jul 92° 71°
- Aug 93° 70°
- Sep 85° 62°
- Oct 74° 50°
- Nov 63° 39°
- Dec 54° 31°
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 Sulphur each month?
August is the warmest month, with normal highs of 93°F; January the coldest, with normal lows of 28°F. The most precipitation falls in May (5.69 in), the least in January (1.84 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 52°F | 28°F | 40.1°F | 1.84 | – | <1 | 22 | 10 h |
| February | 56°F | 33°F | 44.3°F | 2.19 | – | <1 | 15 | 11 h |
| March | 65°F | 41°F | 52.9°F | 3.17 | – | <1 | 7 | 11 h 50 min |
| April | 72°F | 49°F | 60.3°F | 3.71 | – | <1 | 2 | 13 h |
| May | 79°F | 59°F | 68.7°F | 5.69 | – | 1 | <1 | 14 h |
| June | 87°F | 67°F | 77.3°F | 4.60 | – | 15 | <1 | 14 h 30 min |
| July | 92°F | 71°F | 81.6°F | 3.24 | – | 23 | <1 | 14 h 20 min |
| August | 93°F | 70°F | 81.7°F | 2.63 | – | 23 | <1 | 13 h 30 min |
| September | 85°F | 62°F | 73.8°F | 4.30 | – | 11 | <1 | 12 h 30 min |
| October | 74°F | 50°F | 62.0°F | 4.08 | – | 1 | 2 | 11 h 20 min |
| November | 63°F | 39°F | 51.1°F | 2.59 | – | <1 | 9 | 10 h 20 min |
| December | 54°F | 31°F | 42.0°F | 2.64 | – | <1 | 19 | 9 h 50 min |
| Year (annual) | 73°F | 50°F | 61.3°F | 40.68 | – | 75 | 75 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 11°C | −2°C | 4.5°C | 47 mm |
| February | 13°C | 0°C | 6.8°C | 56 mm |
| March | 18°C | 5°C | 11.6°C | 81 mm |
| April | 22°C | 9°C | 15.7°C | 94 mm |
| May | 26°C | 15°C | 20.4°C | 145 mm |
| June | 31°C | 20°C | 25.2°C | 117 mm |
| July | 33°C | 22°C | 27.6°C | 82 mm |
| August | 34°C | 21°C | 27.6°C | 67 mm |
| September | 30°C | 17°C | 23.2°C | 109 mm |
| October | 23°C | 10°C | 16.7°C | 104 mm |
| November | 17°C | 4°C | 10.6°C | 66 mm |
| December | 12°C | −1°C | 5.6°C | 67 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Chickasaw Nra (5 miles away), gets 2 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00348570; 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 Sulphur?
Normal highs sit between 65°F and 85°F in April, May and October.
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 USC00348570.
When is the last frost in Sulphur?
In Sulphur, the last spring frost (32°F) comes after April 4 in half of years and after April 24 in one year in ten; the first autumn frost comes before November 1 in half of years and before October 17 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 41 year in 10 after April 24; 9 in 10 after March 15
- First autumn frost, half of years before
- November 11 year in 10 before October 17; 9 in 10 before November 17
NOAA puts the median frost-free season at 212 days, and the season without a hard freeze (28°F) at 236 days.
A hard freeze (28°F) comes after March 20 in half of springs and before November 10 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sulphur in zone 7b in ZIP code 73086, the nearest ZIP area.
Frost dates for every NOAA station in Oklahoma · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00348570; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Sulphur?
In a normal year in Sulphur, 75 days a year reach 90°F (12 of them 100°F or more) and 75 nights fall to 32°F or colder.
- Days at 90°F or more
- 75a normal year
- Days at 100°F or more
- 12a normal year
- Nights at 32°F or colder
- 75a normal year
- Days that stay below freezing
- 5high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00348570.
How sunny is Sulphur?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Sulphur, 4.6 kWh per square metre a day. July is the sunniest month (87%) and February the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 74% | 2.7 |
| February | 70% | 3.3 |
| March | 72% | 4.3 |
| April | 74% | 5.4 |
| May | 74% | 5.8 |
| June | 83% | 6.7 |
| July | 87% | 6.8 |
| August | 86% | 6.1 |
| September | 82% | 5.0 |
| October | 79% | 3.9 |
| November | 77% | 3.0 |
| December | 72% | 2.4 |
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 Sulphur need?
A normal year in Sulphur brings 3,294 heating degree days, 39% fewer than the median U.S. place (5,373), and 1,984 cooling degree days, 2.2 times the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 5,214 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 773 | 0 |
| February | 581 | 3 |
| March | 391 | 14 |
| April | 182 | 42 |
| May | 47 | 160 |
| June | 0 | 369 |
| July | 0 | 516 |
| August | 0 | 517 |
| September | 15 | 279 |
| October | 168 | 75 |
| November | 424 | 8 |
| December | 713 | 1 |
| Year (annual) | 3,294 | 1,984 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00348570. 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 Sulphur been warmer than normal lately?
2025 averaged 62.6°F, 1.3°F above the 1991-2020 normal of 61.3°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 61.5°F | +0.2°F | 37.99 |
| 2022 | 62.1°F | +0.8°F | 27.73 |
| 2023 | 63.0°F | +1.7°F | 38.09 |
| 2024 | 64.0°F | +2.7°F | 41.61 |
| 2025 | 62.6°F | +1.3°F | 41.92 |
Source: observed years: ACIS, station USC00348570. A year counts only with all twelve months complete.
How does Sulphur's climate compare?
Sulphur is warmer than 94 of the other 133 places with their own NOAA record in Oklahoma, and wetter than 61. Across the 7,247 U.S. stations with normals, its annual mean of 61.3°F is warmer than 78%.
In the Köppen classification computed from these normals, Sulphur is Cfa: temperate, 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 Sulphur share this climate record?
2 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.
- Roff, OK629 people · 8 mi NE
- Hickory, OK82 people · 6 mi E
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 Sulphur's climate
What is the coldest month in Sulphur?
January, with a normal high of 52°F and a normal low of 28°F. The warmest is August (93°F by day, 70°F at night).
Does it snow in Sulphur?
Yes. NOAA publishes no 1991-2020 snowfall normal for Sulphur's NOAA station; the nearest record that keeps one, Chickasaw Nra (5 miles away), records 2 inches of snow in a normal year.
What is the rainiest month in Sulphur?
May, with 5.69 in of precipitation in a normal year; the driest is January with 1.84 in.
What plant hardiness zone is Sulphur in?
The USDA's 2023 map puts Sulphur in zone 7b in ZIP code 73086, the nearest ZIP area.
How late can frost come in Sulphur?
In half of years the last 32°F night comes after April 4; in one year in ten it comes after April 24. Waiting until April 24 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Oklahoma climateThe statewide normals and every place in the state
- Chickasaw Nra, OK5 miles from this station, 61.5°F a year
- Fittstown, OK13 miles from this station, 61.0°F a year
- Pauls Valley, OK19 miles from this station, 62.2°F a year
- Byars, OK20 miles from this station, 61.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made