Average Weather in Florissant Missouri, United States
In Florissant, the summers are hot and muggy, the winters are very cold and windy, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 25°F to 89°F and is rarely below 8°F or above 97°F.
Based on the tourism score, the best times of year to visit Florissant for warm-weather activities are from late May to early July and from late July to late September.
The hot season lasts for 3.7 months, from May 27 to September 18, with an average daily high temperature above 79°F. The hottest day of the year is July 21, with an average high of 89°F and low of 72°F.
The cold season lasts for 3.0 months, from November 28 to February 27, with an average daily high temperature below 50°F. The coldest day of the year is January 22, with an average low of 25°F and high of 40°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
In Florissant, 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 Florissant begins around June 14 and lasts for 4.4 months, ending around October 27. On August 27, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 71% of the time, and overcast or mostly cloudy 29% of the time.
The cloudier part of the year begins around October 27 and lasts for 7.6 months, ending around June 14. On February 12, the cloudiest day of the year, the sky is overcast or mostly cloudy 54% of the time, and clear, mostly clear, or partly cloudy 46% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Florissant varies throughout the year.
The wetter season lasts 5.7 months, from March 20 to September 12, with a greater than 28% chance of a given day being a wet day. The chance of a wet day peaks at 40% on May 21.
The drier season lasts 6.3 months, from September 12 to March 20. The smallest chance of a wet day is 16% on January 28.
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 40% on May 21.
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. Florissant experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Florissant. The most rain falls during the 31 days centered around May 16, with an average total accumulation of 4.1 inches.
The least rain falls around January 24, with an average total accumulation of 1.4 inches.
Average Monthly Rainfall
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Florissant experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 3.8 months, from November 24 to March 17, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 27, with an average total liquid-equivalent accumulation of 0.4 inches.
The snowless period of the year lasts for 8.2 months, from March 17 to November 24. The least snow falls around July 28, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Florissant varies significantly over the course of the year. In 2018, the shortest day is December 21, with 9 hours, 27 minutes of daylight; the longest day is June 21, with 14 hours, 53 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:35 AM on June 14, and the latest sunrise is 1 hour, 55 minutes later at 7:30 AM on November 3. The earliest sunset is at 4:39 PM on December 7, and the latest sunset is 3 hours, 51 minutes later at 8:30 PM on June 27.
Daylight saving time (DST) is observed in Florissant 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
Florissant experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 4.1 months, from May 20 to September 24, during which time the comfort level is muggy, oppressive, or miserable at least 17% of the time. The muggiest day of the year is July 24, with muggy conditions 69% of the time.
The least muggy day of the year is February 2, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
The average hourly wind speed in Florissant experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 7.1 months, from October 13 to May 18, with average wind speeds of more than 7.9 miles per hour. The windiest day of the year is April 1, with an average hourly wind speed of 10.1 miles per hour.
The calmer time of year lasts for 4.9 months, from May 18 to October 13. The calmest day of the year is July 31, with an average hourly wind speed of 5.8 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Florissant varies throughout the year.
The wind is most often from the south for 9.6 months, from February 22 to December 10, with a peak percentage of 43% on June 21. The wind is most often from the west for 2.4 months, from December 10 to February 22, with a peak percentage of 34% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Florissant 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 Florissant for general outdoor tourist activities are from late May to early July and from late July to late September, with a peak score in the first week of September.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Florissant for hot-weather activities is from mid June to early September, with a peak score in the last week of July.
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.
The growing season in Florissant typically lasts for 7.1 months (218 days), from around April 1 to around November 4, rarely starting before March 14 or after April 18, and rarely ending before October 17 or after November 24.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms in Florissant should appear around March 16, only rarely appearing before March 3 or after April 4.
Growing Degree Days
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 4.1 months, from April 27 to August 29, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest day of the year is July 2, with an average of 6.8 kWh.
The darker period of the year lasts for 3.1 months, from November 6 to February 9, with an average daily incident shortwave energy per square meter below 3.0 kWh. The darkest day of the year is December 23, with an average of 2.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Florissant are 38.789 deg latitude, -90.323 deg longitude, and 541 ft elevation.
The topography within 2 miles of Florissant contains only modest variations in elevation, with a maximum elevation change of 167 feet and an average elevation above sea level of 541 feet. Within 10 miles also contains only modest variations in elevation (482 feet). Within 50 miles contains only modest variations in elevation (771 feet).
The area within 2 miles of Florissant is covered by artificial surfaces (100%), within 10 miles by artificial surfaces (55%) and cropland (28%), and within 50 miles by cropland (55%) and trees (30%).
This report illustrates the typical weather in Florissant, 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Florissant.
For each station, the records are corrected for the elevation difference between that station and Florissant 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 Florissant is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Florissant and a given station.
The stations contributing to this reconstruction are: Lambert–St. Louis International Airport (72%, 6 kilometers, southwest); St. Charles, St. Charles County Smartt Airport (13%, 18 kilometers, northwest); Saint Louis Regional Airport (8%, 26 kilometers, northeast); and Saint Louis Downtown - Parks Airport (7%, 28 kilometers, southeast).
Time zones for aiports and weather stations are provided by AskGeo.com .