Average Weather in Cilaos Réunion
In Cilaos, the wet season is comfortable, humid, and partly cloudy; the dry season is cool and mostly clear; and it is windy year round. Over the course of the year, the temperature typically varies from 48°F to 70°F and is rarely below 45°F or above 72°F.
Based on the tourism score, the best time of year to visit Cilaos for warm-weather activities is from mid October to late May.
The warm season lasts for 3.9 months, from December 9 to April 7, with an average daily high temperature above 68°F. The hottest day of the year is January 25, with an average high of 70°F and low of 58°F.
The cool season lasts for 3.4 months, from June 12 to September 24, with an average daily high temperature below 62°F. The coldest day of the year is August 9, with an average low of 48°F and high of 60°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 Cilaos, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.
The clearer part of the year in Cilaos begins around April 20 and lasts for 7.0 months, ending around November 21. On September 2, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 94% of the time, and overcast or mostly cloudy 6% of the time.
The cloudier part of the year begins around November 21 and lasts for 5.0 months, ending around April 20. On January 12, the cloudiest day of the year, the sky is overcast or mostly cloudy 63% of the time, and clear, mostly clear, or partly cloudy 37% 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 Cilaos varies significantly throughout the year.
The wetter season lasts 4.1 months, from December 21 to April 23, with a greater than 20% chance of a given day being a wet day. The chance of a wet day peaks at 36% on February 10.
The drier season lasts 7.9 months, from April 23 to December 21. The smallest chance of a wet day is 5% on July 13.
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 36% on February 10.
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. Cilaos experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 7.6 months, from October 18 to June 7, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around February 15, with an average total accumulation of 5.0 inches.
The rainless period of the year lasts for 4.4 months, from June 7 to October 18. The least rain falls around July 16, with an average total accumulation of 0.4 inches.
Average Monthly Rainfall
The length of the day in Cilaos varies over the course of the year. In 2017, the shortest day is June 21, with 10 hours, 51 minutes of daylight; the longest day is December 21, with 13 hours, 25 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:27 AM on November 27, and the latest sunrise is 1 hour, 29 minutes later at 6:56 AM on July 5. The earliest sunset is at 5:43 PM on June 6, and the latest sunset is 1 hour, 22 minutes later at 7:05 PM on January 15.
Daylight saving time (DST) is not observed in Cilaos during 2017.
Sunrise & Sunset with Twilight
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.
Cilaos experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 5.2 months, from November 29 to May 4, during which time the comfort level is muggy, oppressive, or miserable at least 17% of the time. The muggiest day of the year is February 6, with muggy conditions 69% of the time.
The least muggy day of the year is July 30, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
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 Cilaos experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 4.1 months, from May 23 to September 27, with average wind speeds of more than 12.1 miles per hour. The windiest day of the year is July 25, with an average hourly wind speed of 14.1 miles per hour.
The calmer time of year lasts for 7.9 months, from September 27 to May 23. The calmest day of the year is November 26, with an average hourly wind speed of 10.0 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Cilaos is from the east throughout the year.
Cilaos 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 4.0 months, from December 26 to April 25, with an average temperature above 80°F. The day of the year with the warmest water is February 16, with an average temperature of 82°F.
The time of year with cooler water lasts for 3.6 months, from July 4 to October 24, with an average temperature below 76°F. The day of the year with the coolest water is August 22, with an average temperature of 74°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Cilaos 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 Cilaos for general outdoor tourist activities is from mid October to late May, with a peak score in the last week of November.
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 Cilaos for hot-weather activities is from early January to late February, with a peak score in the last week of January.
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).
Temperatures in Cilaos are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season
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.
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 3.5 months, from October 12 to January 26, with an average daily incident shortwave energy per square meter above 6.8 kWh. The brightest day of the year is November 22, with an average of 7.5 kWh.
The darker period of the year lasts for 3.1 months, from May 9 to August 11, with an average daily incident shortwave energy per square meter below 4.6 kWh. The darkest day of the year is June 26, with an average of 3.9 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Cilaos are -21.134 deg latitude, 55.472 deg longitude, and 4,757 ft elevation.
The topography within 2 miles of Cilaos contains extreme variations in elevation, with a maximum elevation change of 6,814 feet and an average elevation above sea level of 4,281 feet. Within 10 miles also contains extreme variations in elevation (9,685 feet). Within 50 miles also contains extreme variations in elevation (10,026 feet).
The area within 2 miles of Cilaos is covered by trees (82%) and shrubs (14%), within 10 miles by trees (83%) and shrubs (11%), and within 50 miles by water (91%).
This report illustrates the typical weather in Cilaos, 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 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Cilaos.
For each station, the records are corrected for the elevation difference between that station and Cilaos 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 Cilaos is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Cilaos and a given station.
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.