Portland, Tennessee climate: Normal weather by month, frost dates and records
Portland's normal year runs from 27°F January nights to 89°F July afternoons, with 54.3 inches of precipitation and 2 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.6°C, January lows of −3°C, July highs of 32°C, 1,379 mm of precipitation a year.
- NOAA stationPortland Sewage Plant
- Station IDUSC00407359
- Location36.59°N 86.53°W
- Elevation794 ft (242 m)
- Population13,651
On October 14, the normal high in Portland is 72°F and the normal low 49°F, and the chance of measurable rain or snow is 27%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Portland.
- Jan 45° 27°
- Feb 50° 30°
- Mar 59° 37°
- Apr 70° 47°
- May 78° 57°
- Jun 85° 65°
- Jul 89° 69°
- Aug 88° 67°
- Sep 82° 60°
- Oct 71° 48°
- Nov 59° 37°
- Dec 49° 30°
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 Portland each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 27°F. The most precipitation falls in May (5.80 in), the least in September (3.64 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 45°F | 27°F | 36.0°F | 4.20 | 0.2 | 11 | <1 | 21 | 9 h 50 min |
| February | 50°F | 30°F | 39.9°F | 4.69 | 1.5 | 10 | <1 | 17 | 10 h 50 min |
| March | 59°F | 37°F | 48.1°F | 5.08 | 0.3 | 12 | <1 | 10 | 11 h 50 min |
| April | 70°F | 47°F | 58.2°F | 5.24 | 0.0 | 11 | <1 | 2 | 13 h 10 min |
| May | 78°F | 57°F | 67.2°F | 5.80 | 0.0 | 11 | 1 | <1 | 14 h 10 min |
| June | 85°F | 65°F | 75.1°F | 4.36 | 0.0 | 10 | 7 | <1 | 14 h 40 min |
| July | 89°F | 69°F | 78.6°F | 4.57 | 0.0 | 10 | 14 | <1 | 14 h 30 min |
| August | 88°F | 67°F | 77.5°F | 4.15 | 0.0 | 8 | 12 | <1 | 13 h 40 min |
| September | 82°F | 60°F | 70.9°F | 3.64 | 0.0 | 8 | 5 | <1 | 12 h 30 min |
| October | 71°F | 48°F | 59.7°F | 3.69 | 0.0 | 8 | <1 | 1 | 11 h 20 min |
| November | 59°F | 37°F | 48.2°F | 3.78 | 0.0 | 9 | <1 | 10 | 10 h 20 min |
| December | 49°F | 30°F | 39.6°F | 5.11 | 0.0 | 11 | <1 | 18 | 9 h 40 min |
| Year (annual) | 69°F | 48°F | 58.2°F | 54.31 | 2.0 | 119 | 38 | 80 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 7°C | −3°C | 2.2°C | 107 mm | 1 cm |
| February | 10°C | −1°C | 4.4°C | 119 mm | 4 cm |
| March | 15°C | 3°C | 8.9°C | 129 mm | 1 cm |
| April | 21°C | 8°C | 14.6°C | 133 mm | 0 cm |
| May | 25°C | 14°C | 19.6°C | 147 mm | 0 cm |
| June | 30°C | 18°C | 23.9°C | 111 mm | 0 cm |
| July | 32°C | 20°C | 25.9°C | 116 mm | 0 cm |
| August | 31°C | 19°C | 25.3°C | 105 mm | 0 cm |
| September | 28°C | 15°C | 21.6°C | 92 mm | 0 cm |
| October | 22°C | 9°C | 15.4°C | 94 mm | 0 cm |
| November | 15°C | 3°C | 9.0°C | 96 mm | 0 cm |
| December | 9°C | −1°C | 4.2°C | 130 mm | 0 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00407359; 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 Portland?
Normal highs sit between 65°F and 85°F in April, May, September and October. Of those, September has the fewest days with rain (8).
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 USC00407359.
When is the last frost in Portland?
In Portland, the last spring frost (32°F) comes after April 5 in half of years and after April 19 in one year in ten; the first autumn frost comes before November 1 in half of years and before October 21 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 51 year in 10 after April 19; 9 in 10 after March 21
- First autumn frost, half of years before
- November 11 year in 10 before October 21; 9 in 10 before November 14
NOAA puts the median frost-free season at 210 days, and the season without a hard freeze (28°F) at 231 days.
A hard freeze (28°F) comes after March 26 in half of springs and before November 11 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Portland in zone 7b in ZIP code 37148. By the map's own method, the average of each year's coldest night over 1991-2020, Portland's NOAA station is in zone 7b: the coldest night of a typical year reaches 6°F (25 complete years).
Frost dates for every NOAA station in Tennessee · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00407359; 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 Portland?
In a normal year in Portland, 38 days a year reach 90°F (1 of them 100°F or more), 80 nights fall to 32°F or colder and 119 days bring measurable precipitation.
- Days at 90°F or more
- 38a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 80a normal year
- Days that stay below freezing
- 12high of 32°F or less
- Days with 0.01 inch of precipitation
- 119a normal year
- Days with 1 inch of snow or more
- 1a normal year
The highest temperature in this station's record (since 1955) is 106°F, on June 30, 2012; the lowest is −19°F, on January 24, 1963.
The wettest calendar year on that record is 1957, with 65.66 in; the snowiest season is 1977–78, with 35.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00407359; records: ACIS (NOAA Regional Climate Centers), station USC00407359. Records use complete months only; a month missing more than three days is left out.
How sunny is Portland?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Portland, 4.2 kWh per square metre a day. August is the sunniest month (81%) and February the cloudiest (62%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 2.2 |
| February | 62% | 2.8 |
| March | 67% | 3.9 |
| April | 74% | 5.2 |
| May | 75% | 5.7 |
| June | 80% | 6.3 |
| July | 80% | 6.1 |
| August | 81% | 5.6 |
| September | 79% | 4.7 |
| October | 75% | 3.6 |
| November | 73% | 2.6 |
| December | 64% | 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 Portland need?
A normal year in Portland brings 3,984 heating degree days, 26% fewer than the median U.S. place (5,373), and 1,545 cooling degree days, 70% 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 4,529 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 900 | 0 |
| February | 703 | 1 |
| March | 532 | 7 |
| April | 242 | 36 |
| May | 71 | 137 |
| June | 4 | 306 |
| July | 0 | 423 |
| August | 1 | 388 |
| September | 26 | 203 |
| October | 207 | 41 |
| November | 509 | 3 |
| December | 789 | 0 |
| Year (annual) | 3,984 | 1,545 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00407359. 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 Portland been warmer than normal lately?
2023 averaged 59.9°F, 1.7°F above the 1991-2020 normal of 58.2°F.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2023 | 59.9°F | +1.7°F | 58.17 | 0.0 |
Over 46 complete years from 1956 to 2025, the station's annual mean temperature rose at a fitted 1.0°F per century (+0.05°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00407359; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Portland's climate compare?
Portland is warmer than 52 of the other 115 places with their own NOAA record in Tennessee, and wetter than 31. Across the 7,247 U.S. stations with normals, its annual mean of 58.2°F is warmer than 69%.
In the Köppen classification computed from these normals, Portland 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 Portland 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.
- Franklin, KY10,524 people · 9 mi N
- Orlinda, TN1,005 people · 10 mi W
- Woodburn, KY331 people · 18 mi N
- New Deal, TN214 people · 6 mi S
- Mitchellville, TN160 people · 3 mi N
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 Portland's climate
What is the coldest month in Portland?
January, with a normal high of 45°F and a normal low of 27°F. The warmest is July (89°F by day, 69°F at night).
Does it snow in Portland?
Yes: 2 inches in a normal year, falling on 2 days with 0.1 inch or more, the most in February (1.5 inches).
What is the rainiest month in Portland?
May, with 5.80 in of precipitation in a normal year; the driest is September with 3.64 in.
What plant hardiness zone is Portland in?
The USDA's 2023 map puts Portland in zone 7b in ZIP code 37148. By the same method at Portland's NOAA station, the coldest night of a typical year reaches 6°F (25 years, 1991-2020): zone 7b.
How late can frost come in Portland?
In half of years the last 32°F night comes after April 5; in one year in ten it comes after April 19. Waiting until April 19 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Tennessee climateThe statewide normals and every place in the state
- White House, TN12 miles from this station, 58.2°F a year
- Bethpage, TN14 miles from this station, 56.7°F a year
- Springfield, TN19 miles from this station, 58.1°F a year
- Scottsville, KY20 miles from this station, 57.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made