Weather in December — Sebastian, Florida

December in Sebastian is mild by day and cool at night, with a Vero Beach normal of 75.4 degrees for the high and 56.1 for the low, and a freezing night only about once every three Decembers.

The December daily normals for the Vero Beach airport show winter settling in over the month: the expected high goes from 77.1 degrees on December 1 to 73.7 on December 31, and the low from 58.6 to 53.4. By New Year's Eve the normal low in Indian River County is about five degrees colder than at the start of December. The month as a whole, per the monthly normals, averages 65.7 degrees.

Cold nights are common but hard freezes are rare. NOAA's threshold-day normals count 9.4 December nights at 50 degrees or colder at Vero Beach and 0.3 nights at 32 or colder. Melbourne, the Brevard County airport station north of the Sebastian River, runs a little cooler, with December normals of 73.9 over 55.6.

Yes: the coldest December reading at Vero Beach is 23 degrees on December 24, 1989, part of a Christmas freeze that NWS Melbourne describes as devastating across east central Florida.

The NWS Melbourne December 2025 climate summary carries the Vero Beach station records: a December low of 23 on December 24, 1989 and a high of 89 on December 2 and 3, 2018. The 1989 cold was not a single night. An NWS Melbourne forecast discussion issued on Christmas Eve 2018 noted that all but one of the record lows for December 23, 24, 25 and 26 in its records were set in either 1983 or 1989, that lows in east central Florida dropped into the upper teens to low 20s for consecutive days, and that highs struggled to reach the 40s at times.

Measured against the normal of 0.3 freezing nights per December at Vero Beach, a week like Christmas 1989 sits far outside the usual range for Sebastian and the Indian River County coast. The 2025 holiday season shows the more typical pattern: the coldest morning of that December was 34 degrees, on December 31.

Sebastian's December cold comes in two forms that UF/IFAS Extension distinguishes: calm, clear radiational frosts and windy advective freezes driven by cold air from the north.

In its Cold Protection of Landscape Plants publication, UF/IFAS Extension explains that radiational freezes form on calm, clear nights when heat radiates away from plants and other surfaces, while advective freezes arrive when cold air masses move rapidly from the north, with wind and a sudden drop in temperature. Both show up in the Vero Beach record. The coldest morning of December 2025, 34 degrees on December 31, followed a month in which the station logged its top gust, 34 mph from due north, on December 15. The multi-day Christmas freezes of 1983 and 1989 brought consecutive nights in the upper teens to low 20s across east central Florida.

The same publication notes that covers protect plants better against frost than against extreme cold, and that late fall fertilization can push out new growth that is more vulnerable to cold injury. In Sebastian that point sits beside the Indian River County rule that keeps fertilizer off lawns from June 1 through September 30, which leaves fall as the first feeding window for yards in the Sebastian Highlands and along Indian River Drive.

December 2025 was warm and dry at Vero Beach, with an average high of 77.1 degrees, 1.7 above normal, and only 0.72 inches of rain, before a cold snap brought 34 degrees on December 31.

The Vero Beach December 2025 report, issued on January 1, 2026, shows the month's warm spells peaking at 84 degrees on December 5, 6 and 19, and its strongest gust, 34 mph from the north, on December 15. No thunderstorm was logged, while fog was reported on 20 days. December 2024 had been wetter, at 3.73 inches on 11 days, with a lowest reading of 44.

The station's December rainfall record runs from 0.08 inches in 1961 to 6.92 inches in 2019. One December in four brings less than 0.88 inches at Vero Beach, and one in four brings more than 3.44, according to NOAA's rainfall percentiles.

December ocean water near Sebastian Inlet averages about 70 to 77 degrees, from 70.3 at the shallow Trident Pier to 75.6 offshore and 76.7 at Lake Worth Pier.

The NOAA NCEI Coastal Water Temperature Guide shows the nearshore water cooling much faster than the open Atlantic: Trident Pier loses 4.2 degrees from November to December, while the Canaveral buoy loses 3.1. Even so, the ocean beside Sebastian Inlet State Park stays about ten degrees warmer than the 65.7 degree December air mean at Vero Beach.

The cooler months change what can be seen from the park. Florida State Parks lists March to October as the manatee season in the waters around Sebastian Inlet, so December falls outside it, and notes that right whales can sometimes be observed close to the coast in January and February. The park describes stargazing on its Atlantic beaches as best on clear, crisp, cool nights in the winter months.

On the lagoon side, the U.S. Fish and Wildlife Service treats fall through spring as the season for migratory white pelicans and nesting brown pelicans at Pelican Island National Wildlife Refuge, north of Sebastian in the Indian River Lagoon.

Sebastian's December centers on the City of Sebastian Christmas Parade down Indian River Drive to Riverview Park, held after hurricane season has closed on November 30.

In 2025, according to Sebastian Daily, the City of Sebastian Annual Christmas Parade stepped off at 6:30 p.m. on Saturday, December 6, running south on Indian River Drive from Main Street to Riverview Park, where Santa met families and the city's Christmas tree was lit.

The National Hurricane Center closes the Atlantic season on November 30, so December weather in Sebastian is driven by cold fronts rather than tropical systems. For the 2026 to 2027 winter, NWS Melbourne's season pages carried an outlook headline in October 2026 for increased potential for well above normal rainfall and severe weather from November 2026 through April 2027 for east central Florida, the forecast area that covers Sebastian and the rest of Indian River County.