Average Weather in Port Saint John Florida, United States
In Port Saint John, the summers are long, hot, oppressive, wet, and mostly cloudy and the winters are short, cool, windy, and partly cloudy. Over the course of the year, the temperature typically varies from 53°F to 89°F and is rarely below 39°F or above 92°F.
Based on the tourism score, the best times of year to visit Port Saint John for warm-weather activities are from early March to mid May and from mid October to early December.
The hot season lasts for 4.1 months, from May 25 to September 29, with an average daily high temperature above 85°F. The hottest day of the year is August 3, with an average high of 89°F and low of 75°F.
The cool season lasts for 2.8 months, from December 6 to March 1, with an average daily high temperature below 74°F. The coldest day of the year is January 18, with an average low of 53°F and high of 70°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
In Port Saint John, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Port Saint John begins around October 1 and lasts for 8.2 months, ending around June 6. On May 2, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 65% of the time, and overcast or mostly cloudy 35% of the time.
The cloudier part of the year begins around June 6 and lasts for 3.8 months, ending around October 1. On July 6, the cloudiest day of the year, the sky is overcast or mostly cloudy 69% of the time, and clear, mostly clear, or partly cloudy 31% of the time.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Port Saint John varies significantly throughout the year.
The wetter season lasts 4.3 months, from May 28 to October 6, with a greater than 38% chance of a given day being a wet day. The chance of a wet day peaks at 59% on August 25.
The drier season lasts 7.7 months, from October 6 to May 28. The smallest chance of a wet day is 16% on November 21.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 59% on August 25.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Port Saint John experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Port Saint John. The most rain falls during the 31 days centered around August 22, with an average total accumulation of 5.9 inches.
The least rain falls around December 23, with an average total accumulation of 2.0 inches.
Average Monthly Rainfall
The length of the day in Port Saint John varies over the course of the year. In 2018, the shortest day is December 21, with 10 hours, 20 minutes of daylight; the longest day is June 21, with 13 hours, 57 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 6:25 AM on June 10, and the latest sunrise is 1 hour, 12 minutes later at 7:37 AM on March 11. The earliest sunset is at 5:26 PM on December 1, and the latest sunset is 2 hours, 59 minutes later at 8:24 PM on July 1.
Daylight saving time (DST) is observed in Port Saint John during 2018, starting in the spring on March 11, lasting 7.8 months, and ending in the fall on November 4.
Sunrise & Sunset with Twilight and Daylight Saving Time
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.
Port Saint John experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 7.5 months, from April 16 to December 1, during which time the comfort level is muggy, oppressive, or miserable at least 32% of the time. The muggiest day of the year is July 28, with muggy conditions 100% of the time.
The least muggy day of the year is January 31, with muggy conditions 10% of the time.
Humidity Comfort Levels
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Port Saint John experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 8.2 months, from September 23 to May 30, with average wind speeds of more than 9.6 miles per hour. The windiest day of the year is March 10, with an average hourly wind speed of 11.9 miles per hour.
The calmer time of year lasts for 3.8 months, from May 30 to September 23. The calmest day of the year is August 4, with an average hourly wind speed of 7.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Port Saint John varies throughout the year.
The wind is most often from the east for 3.9 months, from February 28 to June 24 and for 3.6 months, from August 12 to December 1, with a peak percentage of 52% on September 24. The wind is most often from the south for 1.6 months, from June 24 to August 12, with a peak percentage of 42% on July 19. The wind is most often from the north for 2.5 months, from December 1 to February 16, with a peak percentage of 31% on January 1.
Port Saint John 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 water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 4.1 months, from June 13 to October 16, with an average temperature above 80°F. The day of the year with the warmest water is August 31, with an average temperature of 83°F.
The time of year with cooler water lasts for 3.4 months, from December 24 to April 7, with an average temperature below 73°F. The day of the year with the coolest water is February 6, with an average temperature of 70°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Port Saint John throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best times of year to visit Port Saint John for general outdoor tourist activities are from early March to mid May and from mid October to early December, with a peak score in the third week of April.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best times of year to visit Port Saint John for hot-weather activities are from late April to early June and from late September to late October, with a peak score in the third week of May.
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
While it does not do so every year, freezing temperatures are seen in Port Saint John over some winters. The day least likely to be in the growing season is January 8, with a 75% chance.
Time Spent in Various Temperature Bands and the Growing Season
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
Based on growing degree days alone, the first spring blooms in Port Saint John should appear around January 9, only rarely appearing before January 6 or after January 14.
Growing Degree Days
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 experiences significant seasonal variation over the course of the year.
The brighter period of the year lasts for 2.0 months, from April 4 to June 4, with an average daily incident shortwave energy per square meter above 6.1 kWh. The brightest day of the year is May 2, with an average of 6.8 kWh.
The darker period of the year lasts for 2.7 months, from November 9 to February 1, with an average daily incident shortwave energy per square meter below 4.0 kWh. The darkest day of the year is December 21, with an average of 3.3 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Port Saint John are 28.477 deg latitude, -80.789 deg longitude, and 20 ft elevation.
The topography within 2 miles of Port Saint John is essentially flat, with a maximum elevation change of 43 feet and an average elevation above sea level of 19 feet. Within 10 miles is also essentially flat (72 feet). Within 50 miles is essentially flat (187 feet).
The area within 2 miles of Port Saint John is covered by artificial surfaces (65%), herbaceous vegetation (18%), and water (14%), within 10 miles by herbaceous vegetation (43%) and artificial surfaces (26%), and within 50 miles by water (46%) and herbaceous vegetation (22%).
This report illustrates the typical weather in Port Saint John, 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 are 6 weather stations near enough to contribute to our estimation of the temperature and dew point in Port Saint John.
For each station, the records are corrected for the elevation difference between that station and Port Saint John according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Port Saint John is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Port Saint John and a given station.
The stations contributing to this reconstruction are: NASA Shuttle Facility (37%, 18 kilometers, northeast); Port Canaveral North Heliport (27%, 22 kilometers, east); Patrick Air Force Base (15%, 33 kilometers, southeast); Orlando International Airport (7%, 53 kilometers, west); Executive Airport (7%, 54 kilometers, west); and Orlando Sanford International Airport (7%, 56 kilometers, northwest).
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.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.