Rock Island State Park, Tennessee climate: Climate normals at a NOAA weather station
Rock Island State Park's normal year runs from 29°F January nights to 87°F July afternoons, with 59.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.9°C, January lows of −1°C, July highs of 30°C, 1,509 mm of precipitation a year.
- NOAA stationRock Island State Park
- Station IDUSC00407808
- Location35.81°N 85.64°W
- Elevation880 ft (268 m)
On October 23, the normal high in Rock Island State Park is 68°F and the normal low 45°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Rock Island State Park.
- Jan 48° 29°
- Feb 53° 32°
- Mar 62° 39°
- Apr 70° 47°
- May 78° 56°
- Jun 84° 64°
- Jul 87° 68°
- Aug 86° 67°
- Sep 80° 61°
- Oct 71° 48°
- Nov 61° 38°
- Dec 52° 32°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Rock Island State Park each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 29°F. The most precipitation falls in December (6.24 in), the least in October (3.46 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 48°F | 29°F | 38.5°F | 5.09 | – | <1 | 21 | 10 h |
| February | 53°F | 32°F | 42.4°F | 5.11 | – | <1 | 16 | 10 h 50 min |
| March | 62°F | 39°F | 50.3°F | 6.02 | – | <1 | 8 | 11 h 50 min |
| April | 70°F | 47°F | 58.6°F | 5.16 | – | <1 | 1 | 13 h |
| May | 78°F | 56°F | 67.0°F | 4.78 | – | 1 | <1 | 14 h |
| June | 84°F | 64°F | 74.3°F | 5.37 | – | 6 | <1 | 14 h 30 min |
| July | 87°F | 68°F | 77.1°F | 5.29 | – | 9 | <1 | 14 h 20 min |
| August | 86°F | 67°F | 76.2°F | 4.29 | – | 8 | <1 | 13 h 30 min |
| September | 80°F | 61°F | 70.4°F | 4.04 | – | 3 | <1 | 12 h 30 min |
| October | 71°F | 48°F | 59.4°F | 3.46 | – | <1 | 1 | 11 h 20 min |
| November | 61°F | 38°F | 49.4°F | 4.56 | – | <1 | 10 | 10 h 20 min |
| December | 52°F | 32°F | 42.2°F | 6.24 | – | <1 | 17 | 9 h 50 min |
| Year (annual) | 69°F | 49°F | 58.8°F | 59.41 | – | 27 | 74 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 9°C | −1°C | 3.6°C | 129 mm |
| February | 11°C | 0°C | 5.8°C | 130 mm |
| March | 16°C | 4°C | 10.2°C | 153 mm |
| April | 21°C | 8°C | 14.8°C | 131 mm |
| May | 26°C | 13°C | 19.4°C | 121 mm |
| June | 29°C | 18°C | 23.5°C | 136 mm |
| July | 30°C | 20°C | 25.1°C | 134 mm |
| August | 30°C | 19°C | 24.6°C | 109 mm |
| September | 27°C | 16°C | 21.3°C | 103 mm |
| October | 22°C | 9°C | 15.2°C | 88 mm |
| November | 16°C | 3°C | 9.7°C | 116 mm |
| December | 11°C | 0°C | 5.7°C | 158 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Sparta (12 miles away), gets 5 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00407808; 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.
Which months are mildest at Rock Island State Park?
Normal highs sit between 65°F and 85°F in April, May, June, September 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 USC00407808.
When is the last frost at Rock Island State Park?
In Rock Island State Park, the last spring frost (32°F) comes after April 6 in half of years and after April 22 in one year in ten; the first autumn frost comes before October 30 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 61 year in 10 after April 22; 9 in 10 after March 22
- First autumn frost, half of years before
- October 301 year in 10 before October 17; 9 in 10 before November 14
NOAA puts the median frost-free season at 207 days, and the season without a hard freeze (28°F) at 230 days.
A hard freeze (28°F) comes after March 26 in half of springs and before November 9 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Rock Island State Park in zone 7b in ZIP code 38550, the nearest ZIP area.
Frost dates for every NOAA station in Tennessee · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00407808; 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 at Rock Island State Park?
In a normal year in Rock Island State Park, 27 days a year reach 90°F (1 of them 100°F or more) and 74 nights fall to 32°F or colder.
- Days at 90°F or more
- 27a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 74a normal year
- Days that stay below freezing
- 7high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00407808.
How sunny is it at Rock Island State Park?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds at Rock Island State Park, 4.3 kWh per square metre a day. August is the sunniest month (79%) and February the cloudiest (62%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 2.3 |
| February | 62% | 2.9 |
| March | 68% | 4.0 |
| April | 74% | 5.3 |
| May | 75% | 5.8 |
| June | 79% | 6.3 |
| July | 78% | 6.0 |
| August | 79% | 5.5 |
| September | 78% | 4.8 |
| October | 76% | 3.7 |
| November | 74% | 2.8 |
| December | 65% | 2.0 |
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 many heating and cooling degree days does Rock Island State Park record?
A normal year at Rock Island State Park brings 3,622 heating degree days, 33% fewer than the median U.S. place (5,373), and 1,402 cooling degree days, 54% more than 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 4,459 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 821 | 0 |
| February | 634 | 1 |
| March | 460 | 6 |
| April | 227 | 33 |
| May | 64 | 127 |
| June | 1 | 280 |
| July | 0 | 375 |
| August | 0 | 349 |
| September | 26 | 189 |
| October | 211 | 37 |
| November | 472 | 4 |
| December | 707 | 0 |
| Year (annual) | 3,622 | 1,402 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00407808. 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.
How does Rock Island State Park's climate compare?
Rock Island State Park is warmer than 69 of the 116 places with their own NOAA record in Tennessee, and wetter than 93. Across the 7,247 U.S. stations with normals, its annual mean of 58.8°F is warmer than 71%.
In the Köppen classification computed from these normals, Rock Island State Park 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.
Questions about Rock Island State Park's climate
What is the coldest month at Rock Island State Park?
January, with a normal high of 48°F and a normal low of 29°F. The warmest is July (87°F by day, 68°F at night).
Does it snow at Rock Island State Park?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Sparta (12 miles away), records 5 inches of snow in a normal year.
What is the rainiest month at Rock Island State Park?
December, with 6.24 in of precipitation in a normal year; the driest is October with 3.46 in.
What plant hardiness zone is Rock Island State Park in?
The USDA's 2023 map puts Rock Island State Park in zone 7b in ZIP code 38550, the nearest ZIP area.
How late can frost come at Rock Island State Park?
In half of years the last 32°F night comes after April 6; in one year in ten it comes after April 22. Waiting until April 22 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Tennessee climateThe statewide normals and every place in the state
- Sparta, TN12 miles from this station, 58.0°F a year
- McMinnville, TN12 miles from this station, 60.2°F a year
- Smithville, TN12 miles from this station, 56.9°F a year
- Fall Creek Falls State Park, TN20 miles from this station, 55.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made