Harbor Island, SC climate
Harbor Island has warm winters and warm summers, with plenty of rain. A typical July afternoon reaches 90°, a January night drops to 41°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Harbor Island feels like
Winter
Spring
Summer
Fall
Harbor Island weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 60° | 41° | 3.3" | 0 | 9 | 0 | 45° – 57° |
| February | 63° | 44° | 3.0" | 0 | 9 | 0 | 46° – 62° |
| March | 68° | 50° | 3.4" | 0 | 9 | 0 | 53° – 66° |
| April | 75° | 57° | 3.2" | 0 | 9 | 0 | 61° – 71° |
| May | 82° | 65° | 3.1" | 0 | 8 | 0 | 69° – 79° |
| June | 87° | 72° | 5.1" | 0 | 13 | 0 | 75° – 84° |
| July | 90° | 75° | 5.9" | 0 | 13 | 0 | 80° – 86° |
| August | 89° | 74° | 6.6" | 0 | 13 | 0 | 79° – 84° |
| September | 85° | 70° | 5.0" | 0 | 10 | 0 | 75° – 82° |
| October | 78° | 60° | 4.4" | 0 | 8 | 0 | 65° – 74° |
| November | 69° | 50° | 2.6" | 0 | 8 | 0 | 55° – 66° |
| December | 62° | 44° | 3.1" | 0 | 10 | 0 | 44° – 64° |
| Year | 76° | 59° | 48.7" | 0.0" | 118 | 0 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Harbor Island
Harbor Island gets 49 inches of rain and melted snow a year. August is the wettest month and November the driest. Rain or snow falls on about 118 days a year.
About 280 frost-free days a year
In half of years the last 32° night comes by March 1 and the first one by December 6. That leaves about 280 frost-free days for gardens, longer than 94% of U.S. towns.
Heating and cooling a home in Harbor Island
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Harbor Island, 48% of that work is heating and 52% is cooling.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How Harbor Island compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Harbor Island averaged 1.1° warmer than the 1900s. The biggest change is in December (+2.1°). The shift is smaller than in 65% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Harbor Island’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 44° to 64°. August is the most reliable, staying within 5°.
Common questions about Harbor Island’s climate
What is the coldest month in Harbor Island?
January, with a typical high of 60° and a low of 41°.
What is the hottest month in Harbor Island?
July, with a typical high of 90° and a low of 75°. About 42 days a year reach 90°.
How much snow does Harbor Island get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in Harbor Island?
In half of years the first 32° night comes by December 6, and the last spring frost by March 1.
What is the rainiest month in Harbor Island?
August, with 6.6 inches of rain and melted snow. The year totals 49 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Harbor Island itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Beaufort Mcas, SC (17 mi, snow) and Edisto Beach Sp, SC (11 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.