Winter Weather in Johannesburg Gauteng, South Africa

Daily high temperatures increase by 7°F, from 64°F to 71°F, rarely falling below 54°F or exceeding 78°F. The lowest daily average high temperature is 61°F on July 3.

Daily low temperatures increase by 6°F, from 39°F to 45°F, rarely falling below 30°F or exceeding 51°F. The lowest daily average low temperature is 36°F on July 4.

For reference, on January 1, the hottest day of the year, temperatures in Johannesburg typically range from 59°F to 78°F, while on July 4, the coldest day of the year, they range from 36°F to 61°F.

The figure below shows you a compact characterization of the hourly average winter temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Campo Quijano, Argentina (5,694 miles away) is the far-away foreign place with temperatures most similar to Johannesburg (view comparison).

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The winter in Johannesburg experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 10% throughout the season. The lowest chance of overcast or mostly cloudy conditions is 8% on July 20.

The clearest day of the winter is July 20, with clear, mostly clear, or partly cloudy conditions 92% of the time.

For reference, on November 24, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 38%, while on July 20, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 92%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Johannesburg, the chance of a wet day over the course of the winter is essentially constant, remaining around 3% throughout.

For reference, the year's highest daily chance of a wet day is 55% on December 16, and its lowest chance is 1% on July 7.

Rainfall

To show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during the winter in Johannesburg is essentially constant, remaining about 0.3 inches throughout, and rarely exceeding 1.4 inches.

The lowest average 31-day accumulation is 0.1 inches on July 13.

Over the course of the winter in Johannesburg, the length of the day is increasing. From the start to the end of the season, the length of the day increases by 58 minutes, implying an average daily increase of 38 seconds, and weekly increase of 4 minutes, 29 seconds.

The shortest day of the winter is June 20, with 10 hours, 30 minutes of daylight and the longest day is August 31, with 11 hours, 34 minutes of daylight.

The latest sunrise of the winter in Johannesburg is 6:56 AM on July 2 and the earliest sunrise is 35 minutes earlier at 6:21 AM on August 31.

The earliest sunset is 5:23 PM on June 8 and the latest sunset is 32 minutes later at 5:55 PM on August 31.

Daylight saving time is not observed in Johannesburg during 2024.

For reference, on December 21, the longest day of the year, the Sun rises at 5:12 AM and sets 13 hours, 47 minutes later, at 6:59 PM, while on June 20, the shortest day of the year, it rises at 6:54 AM and sets 10 hours, 30 minutes later, at 5:24 PM.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

The figure below presents a compact representation of key lunar data for the winter of 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

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.

The chance that a given day will be muggy in Johannesburg is essentially constant during the winter, remaining around 0% throughout.

For reference, on February 23, the muggiest day of the year, there are muggy conditions 2% of the time, while on April 12, the least muggy day of the year, there are muggy conditions 0% of the time.

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 Johannesburg is increasing during the winter, increasing from 7.4 miles per hour to 9.4 miles per hour over the course of the season.

For reference, on September 24, the windiest day of the year, the daily average wind speed is 9.7 miles per hour, while on March 30, the calmest day of the year, the daily average wind speed is 6.4 miles per hour.

The wind direction in Johannesburg during the winter is predominantly out of the south from June 1 to June 29 and the north from June 29 to August 31.

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).

The growing season in Johannesburg typically lasts for 9.9 months (301 days), from around August 4 to around June 2, rarely starting after September 5, or ending before May 11.

The smallest chance that a given day will be within the growing season in Johannesburg during the winter is 11% on June 28.

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.

The average accumulated growing degree days in Johannesburg are very rapidly decreasing during the winter, decreasing by 3,747°F, from 4,050°F to 303°F, over the course of the season.

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 in Johannesburg is rapidly increasing during the winter, rising by 1.5 kWh, from 4.4 kWh to 5.9 kWh, over the course of the season.

The lowest average daily incident shortwave solar energy during the winter is 4.2 kWh on June 20.

For the purposes of this report, the geographical coordinates of Johannesburg are -26.202 deg latitude, 28.044 deg longitude, and 5,797 ft elevation.

The topography within 2 miles of Johannesburg contains only modest variations in elevation, with a maximum elevation change of 440 feet and an average elevation above sea level of 5,705 feet. Within 10 miles contains only modest variations in elevation (1,230 feet). Within 50 miles contains very significant variations in elevation (2,851 feet).

The area within 2 miles of Johannesburg is covered by artificial surfaces (99%), within 10 miles by artificial surfaces (76%) and grassland (17%), and within 50 miles by grassland (44%) and cropland (30%).