Average Weather in September in Naples Florida, United States
In Naples, the month of September is characterized by gradually falling daily high temperatures, with daily highs decreasing by 2°F, from 89°F to 87°F over the course of the month, and rarely exceeding 92°F or dropping below 83°F.
Daily low temperatures decrease by 2°F, from 76°F to 74°F, rarely falling below 70°F or exceeding 79°F.
For reference, on August 8, the hottest day of the year, temperatures in Naples typically range from 76°F to 89°F, while on January 18, the coldest day of the year, they range from 56°F to 73°F.
Average High and Low Temperature in September
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature in September
The month of September in Naples experiences decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 69% to 58%.
The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 42% of the time.
For reference, on August 28, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 71%, while on February 21, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 69%.
Cloud Cover Categories in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Naples, the chance of a wet day over the course of September is very rapidly decreasing, starting the month at 69% and ending it at 48%.
For reference, the year's highest daily chance of a wet day is 73% on August 21, and its lowest chance is 13% on December 17.
Probability of Precipitation in September
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during September in Naples is rapidly decreasing, starting the month at 6.3 inches, when it rarely exceeds 9.8 inches or falls below 3.5 inches, and ending the month at 4.7 inches, when it rarely exceeds 7.5 inches or falls below 2.0 inches.
Average Monthly Rainfall in September
Over the course of September in Naples, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 44 minutes, implying an average daily decrease of 1 minute, 31 seconds, and weekly decrease of 10 minutes, 36 seconds.
The shortest day of the month is September 30, with 11 hours, 55 minutes of daylight and the longest day is September 1, with 12 hours, 39 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Naples is 7:07 AM on September 1 and the latest sunrise is 12 minutes later at 7:19 AM on September 30.
The latest sunset is 7:46 PM on September 1 and the earliest sunset is 32 minutes earlier at 7:14 PM on September 30.
Daylight saving time is observed in Naples during 2017, but it neither starts nor ends during September, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 6:35 AM and sets 13 hours, 47 minutes later, at 8:22 PM, while on December 21, the shortest day of the year, it rises at 7:10 AM and sets 10 hours, 30 minutes later, at 5:40 PM.
Sunrise & Sunset with Twilight in September
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
The chance that a given day will be muggy in Naples is decreasing during September, falling from 100% to 93% over the course of the month.
For reference, on August 20, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 27, the least muggy day of the year, there are muggy conditions 19% of the time.
Humidity Comfort Levels in September
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in Naples is increasing during September, increasing from 7.4 miles per hour to 8.8 miles per hour over the course of the month.
For reference, on November 7, the windiest day of the year, the daily average wind speed is 10.8 miles per hour, while on August 9, the calmest day of the year, the daily average wind speed is 6.4 miles per hour.
Average Wind Speed in September
Wind Direction in September
Naples is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average surface water temperature in Naples is gradually decreasing during September, falling by 2°F, from 86°F to 84°F, over the course of the month.
Average Water Temperature in September
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy in Naples is essentially constant during September, remaining within 0.1 kWh of 4.5 kWh throughout.
The lowest average daily incident shortwave solar energy during September is 4.3 kWh on September 13.
Average Daily Incident Shortwave Solar Energy in September
For the purposes of this report, the geographical coordinates of Naples are 26.142 deg latitude, -81.796 deg longitude, and 3 ft elevation.
The topography within 2 miles of Naples is essentially flat, with a maximum elevation change of 7 feet and an average elevation above sea level of 3 feet. Within 10 miles is also essentially flat (16 feet). Within 50 miles is also essentially flat (39 feet).
The area within 2 miles of Naples is covered by artificial surfaces (78%) and water (20%), within 10 miles by water (48%) and artificial surfaces (37%), and within 50 miles by water (55%) and herbaceous vegetation (23%).
This report illustrates the typical weather in Naples year round, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There is only a single weather station, Naples Municipal Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of Naples.
At a distance of 2 kilometers from Naples, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.
The station records are corrected for the elevation difference between the station and Naples according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.