Average Weather in Saint-Louis France
In Saint-Louis, the summers are warm, the winters are very cold, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 30°F to 79°F and is rarely below 18°F or above 90°F.
Based on the tourism score, the best time of year to visit Saint-Louis for warm-weather activities is from mid June to early September.
The warm season lasts for 3.2 months, from June 4 to September 10, with an average daily high temperature above 71°F. The hottest day of the year is August 4, with an average high of 79°F and low of 58°F.
The cold season lasts for 3.6 months, from November 16 to March 3, with an average daily high temperature below 48°F. The coldest day of the year is February 8, with an average low of 30°F and high of 42°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 Saint-Louis, 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 Saint-Louis begins around June 11 and lasts for 3.4 months, ending around September 23. On July 23, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 64% of the time, and overcast or mostly cloudy 36% of the time.
The cloudier part of the year begins around September 23 and lasts for 8.6 months, ending around June 11. On November 24, the cloudiest day of the year, the sky is overcast or mostly cloudy 65% of the time, and clear, mostly clear, or partly cloudy 35% 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 Saint-Louis varies throughout the year.
The wetter season lasts 3.8 months, from April 27 to August 21, with a greater than 34% chance of a given day being a wet day. The chance of a wet day peaks at 42% on May 27.
The drier season lasts 8.2 months, from August 21 to April 27. The smallest chance of a wet day is 26% on March 3.
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 42% on May 27.
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. Saint-Louis experiences some seasonal variation in monthly rainfall.
Rain falls throughout the year in Saint-Louis. The most rain falls during the 31 days centered around May 31, with an average total accumulation of 3.5 inches.
The least rain falls around February 23, with an average total accumulation of 1.7 inches.
Average Monthly Rainfall
The sliding 31-day liquid-equivalent quantity of snowfall in Saint-Louis does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Saint-Louis varies significantly over the course of the year. In 2018, the shortest day is December 21, with 8 hours, 26 minutes of daylight; the longest day is June 21, with 15 hours, 59 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:31 AM on June 16, and the latest sunrise is 2 hours, 47 minutes later at 8:17 AM on January 1. The earliest sunset is at 4:38 PM on December 11, and the latest sunset is 4 hours, 53 minutes later at 9:31 PM on June 25.
Daylight saving time (DST) is observed in Saint-Louis during 2018, starting in the spring on March 25, lasting 7.1 months, and ending in the fall on October 28.
Sunrise & Sunset with Twilight and Daylight Saving Time
The perceived humidity level in Saint-Louis, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 3% of 3% throughout.
Humidity Comfort Levels
The average hourly wind speed in Saint-Louis experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 5.0 months, from November 21 to April 23, with average wind speeds of more than 6.8 miles per hour. The windiest day of the year is February 6, with an average hourly wind speed of 8.1 miles per hour.
The calmer time of year lasts for 7.0 months, from April 23 to November 21. The calmest day of the year is August 10, with an average hourly wind speed of 5.5 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Saint-Louis is from the west throughout the year.
Best Time of Year to Visit
To characterize how pleasant the weather is in Saint-Louis 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 time of year to visit Saint-Louis for general outdoor tourist activities is from mid June to early September, with a peak score in the first week of August.
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 Saint-Louis for hot-weather activities is from early July to mid August, with a peak score in the first week of August.
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 Saint-Louis typically lasts for 6.7 months (204 days), from around April 11 to around November 1, rarely starting before March 21 or after May 2, and rarely ending before October 12 or after November 25.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms in Saint-Louis should appear around April 11, only rarely appearing before March 27 or after April 26.
Growing Degree Days
The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 3.3 months, from May 10 to August 18, with an average daily incident shortwave energy per square meter above 5.6 kWh. The brightest day of the year is July 6, with an average of 6.8 kWh.
The darker period of the year lasts for 3.6 months, from October 27 to February 15, with an average daily incident shortwave energy per square meter below 2.2 kWh. The darkest day of the year is December 24, with an average of 1.1 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Saint-Louis are 47.588 deg latitude, 7.562 deg longitude, and 850 ft elevation.
The topography within 2 miles of Saint-Louis contains only modest variations in elevation, with a maximum elevation change of 144 feet and an average elevation above sea level of 832 feet. Within 10 miles contains only modest variations in elevation (2,044 feet). Within 50 miles contains large variations in elevation (4,744 feet).
The area within 2 miles of Saint-Louis is covered by artificial surfaces (69%) and cropland (25%), within 10 miles by cropland (45%) and trees (30%), and within 50 miles by trees (44%) and cropland (35%).
This report illustrates the typical weather in Saint-Louis, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Saint-Louis.
For each station, the records are corrected for the elevation difference between that station and Saint-Louis 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 Saint-Louis is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Saint-Louis and a given station.
The stations contributing to this reconstruction are: EuroAirport Basel–Mulhouse–Freiburg (99%, 2.4 kilometers, west); Zurich Airport (0.6%, 75 kilometers, east); and Emmen Air Base (0.6%, 79 kilometers, southeast).
Time zones for aiports and weather stations are provided by AskGeo.com .