Marathon, FL climate
Marathon has warm winters and warm summers. A typical July afternoon reaches 90°, a January night drops to 64°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Marathon feels like
Winter
Spring
Summer
Fall
Marathon 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 | 76° | 64° | 1.9" | 0 | 6 | 0 | 63° – 74° |
| February | 78° | 65° | 1.6" | 0 | 5 | 0 | 65° – 77° |
| March | 80° | 67° | 1.9" | 0 | 4 | 0 | 68° – 79° |
| April | 83° | 71° | 2.2" | 0 | 4 | 0 | 74° – 81° |
| May | 86° | 74° | 3.9" | 0 | 5 | 0 | 77° – 83° |
| June | 89° | 78° | 5.1" | 0 | 10 | 0 | 81° – 86° |
| July | 90° | 79° | 3.9" | 0 | 11 | 0 | 82° – 86° |
| August | 90° | 79° | 5.3" | 0 | 11 | 0 | 83° – 87° |
| September | 89° | 78° | 6.8" | 0 | 13 | 0 | 82° – 85° |
| October | 85° | 75° | 5.4" | 0 | 10 | 0 | 78° – 83° |
| November | 81° | 71° | 2.2" | 0 | 6 | 0 | 72° – 81° |
| December | 78° | 67° | 2.0" | 0 | 7 | 0 | 62° – 79° |
| Year | 84° | 72° | 42.3" | 0.0" | 90 | 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 Marathon
Marathon gets 42 inches of rain and melted snow a year. September is the wettest month and February the driest. Rain or snow falls on about 90 days a year.
A year-round growing season
Heating and cooling a home in Marathon
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Marathon, 1% of that work is heating and 99% is cooling, so air conditioning is the bigger bill.
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 Marathon 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 Marathon averaged 1.8° warmer than the 1900s. The biggest change is in December (+2.6°). The shift is larger than in 86% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Marathon’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 62° to 79°. September is the most reliable, staying within 4°.
Common questions about Marathon’s climate
What is the coldest month in Marathon?
January, with a typical high of 76° and a low of 64°.
What is the hottest month in Marathon?
July, with a typical high of 90° and a low of 79°. About 105 days a year reach 90°.
How much snow does Marathon get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in Marathon?
Frost is uncommon. Only 0% of years see a night at 32° or below.
What is the rainiest month in Marathon?
September, with 6.8 inches of rain and melted snow. The year totals 42 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Marathon itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Duck Key, FL (8 mi, snow) and Marathon Airport, FL (2 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.