Climate and Average Weather Year Round in Wima Sierra Leone

In Wima, the wet season is warm, oppressive, and overcast and the dry season is hot, muggy, and partly cloudy. Over the course of the year, the temperature typically varies from 64°F to 94°F and is rarely below 58°F or above 100°F.

Based on the beach/pool score, the best time of year to visit Wima for hot-weather activities is from mid November to late February.

The hot season lasts for 2.6 months, from January 31 to April 18, with an average daily high temperature above 91°F. The hottest month of the year in Wima is March, with an average high of 94°F and low of 72°F.

The cool season lasts for 3.8 months, from June 26 to October 18, with an average daily high temperature below 83°F. The coldest month of the year in Wima is August, with an average low of 69°F and high of 80°F.

In Wima, 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 Wima begins around November 17 and lasts for 3.7 months, ending around March 8.

The clearest month of the year in Wima is January, during which on average the sky is clear, mostly clear, or partly cloudy 62% of the time.

The cloudier part of the year begins around March 8 and lasts for 8.3 months, ending around November 17.

The cloudiest month of the year in Wima is May, during which on average the sky is overcast or mostly cloudy 78% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Wima varies very significantly throughout the year.

The wetter season lasts 5.7 months, from May 3 to October 25, with a greater than 44% chance of a given day being a wet day. The month with the most wet days in Wima is August, with an average of 26.6 days with at least 0.04 inches of precipitation.

The drier season lasts 6.3 months, from October 25 to May 3. The month with the fewest wet days in Wima is January, with an average of 0.6 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Wima is August, with an average of 26.6 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 88% on August 22.

Rainfall

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. Wima experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.9 months, from February 21 to December 16, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain in Wima is August, with an average rainfall of 18.2 inches.

The rainless period of the year lasts for 2.1 months, from December 16 to February 21. The month with the least rain in Wima is January, with an average rainfall of 0.2 inches.

The length of the day in Wima does not vary substantially over the course of the year, staying within 36 minutes of 12 hours throughout. In 2024, the shortest day is December 21, with 11 hours, 39 minutes of daylight; the longest day is June 20, with 12 hours, 36 minutes of daylight.

The earliest sunrise is at 6:25 AM on May 26, and the latest sunrise is 40 minutes later at 7:05 AM on January 30. The earliest sunset is at 6:21 PM on November 13, and the latest sunset is 46 minutes later at 7:07 PM on July 14.

Daylight saving time (DST) is not observed in Wima during 2024.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

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.

Wima experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 10 months, from February 9 to December 16, during which time the comfort level is muggy, oppressive, or miserable at least 46% of the time. The month with the most muggy days in Wima is August, with 31.0 days that are muggy or worse.

The month with the fewest muggy days in Wima is January, with 9.6 days that are muggy or worse.

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 Wima experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 3.0 months, from June 19 to September 20, with average wind speeds of more than 5.8 miles per hour. The windiest month of the year in Wima is August, with an average hourly wind speed of 7.5 miles per hour.

The calmer time of year lasts for 9.0 months, from September 20 to June 19. The calmest month of the year in Wima is November, with an average hourly wind speed of 3.9 miles per hour.

The predominant average hourly wind direction in Wima varies throughout the year.

The wind is most often from the west for 3.6 months, from February 5 to May 24 and for 1.7 months, from August 9 to October 1, with a peak percentage of 54% on April 4. The wind is most often from the south for 2.5 months, from May 24 to August 9 and for 1.3 months, from October 1 to November 11, with a peak percentage of 56% on July 15. The wind is most often from the east for 2.8 months, from November 11 to February 5, with a peak percentage of 52% on January 1.

To characterize how pleasant the weather is in Wima 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 Wima for general outdoor tourist activities is from early December to late January, with a peak score in the first week of January.

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 Wima for hot-weather activities is from mid November to late February, with a peak score in the last week of January.

Methodology

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 Wima 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.

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.

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 some seasonal variation over the course of the year.

The brighter period of the year lasts for 2.3 months, from January 11 to March 21, with an average daily incident shortwave energy per square meter above 5.4 kWh. The brightest month of the year in Wima is February, with an average of 5.6 kWh.

The darker period of the year lasts for 6.6 months, from May 1 to November 19, with an average daily incident shortwave energy per square meter below 4.7 kWh. The darkest month of the year in Wima is August, with an average of 4.5 kWh.

For the purposes of this report, the geographical coordinates of Wima are 8.301 deg latitude, -11.205 deg longitude, and 1,004 ft elevation.

The topography within 2 miles of Wima contains very significant variations in elevation, with a maximum elevation change of 1,250 feet and an average elevation above sea level of 1,139 feet. Within 10 miles contains very significant variations in elevation (2,119 feet). Within 50 miles contains large variations in elevation (4,741 feet).

The area within 2 miles of Wima is covered by trees (43%), cropland (28%), grassland (15%), and shrubs (14%), within 10 miles by trees (49%) and cropland (26%), and within 50 miles by trees (48%) and cropland (26%).