December in Naples

December's three temperature normals sit between November's and January's, and its rain sits below both: 1.32 inches of rain, a 68.2 F average, a 77.3 F normal high and a 59.0 F normal low. Of the twelve months in NOAA's 1991 to 2020 normals for Naples Municipal Airport, December's 1.32 inch figure is the lowest, and its 0.85 inch median of nonzero monthly totals is the lowest too.

That is a reading of the two central measures, not a count of dry days. NCEI's provisional figures still give the month 4.5 days with at least 0.01 inch of rain, more than November's 3.9 despite carrying less normal rain overall, and 2.4 days with at least 0.10 inch. The middle half of December's nonzero monthly totals in NCEI's record, its first to third quartile, runs 0.47 to 1.75 inches.

In NCEI's month-to-date normals, 0.69 of December's 1.32 inches has typically fallen by the 15th, about 52 percent by arithmetic. NCEI calls its thirty-year figures a ruler for comparing today's weather and a predictor of conditions in the near future; none of them is a forecast for any single December, a distinction the climate normal page keeps in view, and the full twelve months sit in the Naples climate normals table.

NCEI's daily normals for the airport read 60.0 F on December 8 and 59.9 F on December 9, the first day of a stretch that keeps the daily normal minimum under 60 F through March 6. That is a smoothed thirty-year average crossing a round number, not a date on which the weather itself changes.

By NCEI's monthly counts, December registers 14.8 nights at or below 60 F, 5.4 at or below 50 F and 0.5 at or below 40 F, the first nonzero reading of the cool season at the 40 F mark, and a 4.2 percent probability of at least one December night at or below 36 F, the first nonzero reading at that threshold, against 0.0 percent at or below 32 F. November reads 0.0 at both of those marks while already counting 1.8 nights at or below 50 F, so December's first cold nights are first only at 40 F and 36 F.

The National Weather Service defines frost as thin ice crystals forming under conditions similar to dew, except that the temperatures of the surface and earthbound objects fall below 32 F, and adds: “Because frost is primarily an event that occurs as the result of radiational cooling, it frequently occurs with a thermometer level temperature in the mid-30s.” For South Florida, NWS Miami says: “With adequate low level moisture and calm wind, frost may occur at temperatures as warm as the mid 30s.” NCEI's 36 F threshold is the nearest measured proxy for that range and not the same thing, so the 4.2 percent is printed here as NCEI's own number for its own threshold.

The National Weather Service defines a cold front as a “zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer.” NWS Tampa Bay writes for its own region that “In general, overnight low temperatures cannot fall below the dew point,” with lows in the mid 60s to mid 70s under such dew points “unless a cool front moves through during the night,” and NWS Miami's winter climate page ties a negative wintertime North Atlantic Oscillation to cold air outbreaks of Arctic or Polar origin plunging south into Florida. Read as reasoning, the colder nights NCEI counts follow that cooler, drier air; no standing page of either office read for this page counts fronts or their frequency, and none of it forecasts any December. A morning's fog, when it forms, is January's own subject.

December asks a paver sealer the same dryness question as every other month and adds a temperature one. ICPI Tech Spec 5 puts a completely dry surface ahead of most sealers and adds: “Allow at least 24 hours without moisture or surface dampness before application.” SEK-Surebond's TB17 has a surface wet from rain or cleaning dry approximately 24 hours before a sealer, depending on project conditions, and adds that select Surebond sealers can be applied to a damp surface.

The temperature question is December's own, set here as reasoning against the makers' lines. Techniseal's NS sheet: “Temperature must be between 50 and 85°F during the application and for the next 24 hours.” NCEI counts 5.4 December nights at or below 50 F. SEK-Surebond's TB17: “Typically, Surebond sealers should be applied when day and night temperatures are between 40°F and 95°F,” and never on a frozen surface; NCEI counts 0.5 night at or below 40 F. Seal 'n Lock's Super-Wet-Look guide gives 60 F to 90 F for best results and bars application below 50 F, surface or ambient; December's 59.0 F normal low sits just under that best-results line, and NCEI counts 14.8 nights at or below 60 F. An airport air reading is not a paver surface, and an average count of cold nights is not a tally of nights on which a label's window closed; the label in hand and that night's NWS Miami forecast decide, and the winter case is argued in full at sealing pavers in a Naples winter.

Neither GAF's algae bulletin nor ARMA's algae discoloration page names a temperature, dew point or season at which roof algae stops or slows; GAF's bulletin still puts dew first among the organism's moisture sources. The roof's own winter question belongs to can a roof be cleaned in the winter.

Several other calendars touch December, and each has a page of its own.

UF/IFAS Gardening Solutions writes that “some areas experience high pollen counts as early as December,” inside its sentence on the peak season for Florida's oak species; it names no area, and the term pollen season carries the full calendar.

Low winter light on a pane has an answer of its own, why windows look dirty when the sun is low; the PGT, CGI and WinDoor guide's own tip, cleaning glass in cooler temperatures without direct sunlight, names no month, though December's 77.3 F normal high sits among the year's four lowest.

The Atlantic hurricane season sits behind December: the National Hurricane Center's dates are June 1 to November 30, with activity that sometimes occurs after them. A house closed through the summer has what the summer left on a seasonal home before the owners arrive ahead of it, and a cleaning ahead of the holidays has its own page, how soon before an event windows should be cleaned.

A declared water shortage applies by the South Florida Water Management District's own posted terms, which the term water shortage phase tracks; this page restates no status.