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Summer Weather in Johannesburg Gauteng, South Africa

Daily high temperatures are around 77°F, rarely falling below 67°F or exceeding 85°F. The highest daily average high temperature is 78°F on January 1.

Daily low temperatures are around 58°F, rarely falling below 51°F or exceeding 63°F. The highest daily average low temperature is 59°F on January 22.

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.

Average High and Low Temperature in the Summer in Johannesburg

Average High and Low Temperature in the Summer in JohannesburgDecJanFeb45°F45°F50°F50°F55°F55°F60°F60°F65°F65°F70°F70°F75°F75°F80°F80°F85°F85°FSpringFallJan 178°FJan 178°F59°F59°FDec 176°FDec 176°F56°F56°FFeb 2876°FFeb 2876°F58°F58°FFeb 177°FFeb 177°F59°F59°F
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the hourly average summer 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.

Average Hourly Temperature in the Summer in Johannesburg

Average Hourly Temperature in the Summer in JohannesburgDecJanFeb12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMSpringFallcoolcoolcomfortablewarm
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

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 summer in Johannesburg experiences rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 37% to 24%.

The clearest day of the summer is February 25, with clear, mostly clear, or partly cloudy conditions 76% 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%.

Cloud Cover Categories in the Summer in Johannesburg

Cloud Cover Categories in the Summer in JohannesburgDecJanFeb0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%SpringFallDec 163%Dec 163%Feb 2876%Feb 2876%Jan 167%Jan 167%Feb 168%Feb 168%clearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

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 summer is very rapidly decreasing, starting the season at 51% and ending it at 38%.

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.

Probability of Precipitation in the Summer in Johannesburg

Probability of Precipitation in the Summer in JohannesburgDecJanFeb0%0%5%5%10%10%15%15%20%20%25%25%30%30%35%35%40%40%45%45%50%50%55%55%60%60%SpringFallDec 1655%Dec 1655%Dec 151%Dec 151%Feb 2838%Feb 2838%Jan 151%Jan 151%Feb 149%Feb 149%rain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

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 summer in Johannesburg is decreasing, starting the season at 3.6 inches, when it rarely exceeds 6.3 inches or falls below 1.9 inches, and ending the season at 2.9 inches, when it rarely exceeds 5.3 inches or falls below 1.0 inches.

The highest average 31-day accumulation is 3.9 inches on January 17.

Average Monthly Rainfall in the Summer in Johannesburg

Average Monthly Rainfall in the Summer in JohannesburgDecJanFeb0 in0 in1 in1 in2 in2 in3 in3 in4 in4 in5 in5 in6 in6 in7 in7 in8 in8 inSpringFallJan 173.9 inJan 173.9 inDec 13.6 inDec 13.6 inFeb 282.9 inFeb 282.9 inJan 13.8 inJan 13.8 inFeb 13.7 inFeb 13.7 in
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Over the course of the summer in Johannesburg, the length of the day is rapidly decreasing. From the start to the end of the season, the length of the day decreases by 1 hour, 1 minute, implying an average daily decrease of 41 seconds, and weekly decrease of 4 minutes, 50 seconds.

The shortest day of the summer is February 28, with 12 hours, 38 minutes of daylight and the longest day is December 21, with 13 hours, 47 minutes of daylight.

Hours of Daylight and Twilight in the Summer in Johannesburg

Hours of Daylight and Twilight in the Summer in JohannesburgDecJanFeb0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrSpringFallDec 2113 hr, 47 minDec 2113 hr, 47 mindaydaydaydaynightFeb 2812 hr, 38 minFeb 2812 hr, 38 minFeb 113 hr, 17 minFeb 113 hr, 17 min
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the summer in Johannesburg is 5:07 AM on December 1 and the latest sunrise is 54 minutes later at 6:00 AM on February 28.

The latest sunset is 7:05 PM on January 11 and the earliest sunset is 26 minutes earlier at 6:39 PM on February 28.

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.

Sunrise & Sunset with Twilight in the Summer in Johannesburg

Sunrise & Sunset with Twilight in the Summer in JohannesburgDecJanFeb12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMSpringFall5:07 AM5:07 AMDec 16:46 PMDec 16:46 PM5:26 AM5:26 AMJan 117:05 PMJan 117:05 PM6:00 AM6:00 AMFeb 286:39 PMFeb 286:39 PM5:42 AM5:42 AMFeb 16:59 PMFeb 16:59 PMSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day in the summer. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

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.

Solar Elevation and Azimuth in the Summer in Johannesburg

Solar Elevation and Azimuth in the Summer in JohannesburgDecJanFeb12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMSpringFall001020203030405050606070800010102030304040506060707080
northeastsouthwest
Solar elevation and azimuth in the the summer of 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for the summer 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.

Moon Rise, Set & Phases in the Summer in Johannesburg

Moon Rise, Set & Phases in the Summer in JohannesburgDecJanFeb12 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMSpringFallNov 12:48 PMNov 12:48 PMNov 1511:29 PMNov 1511:29 PMDec 18:22 AMDec 18:22 AMDec 1511:02 AMDec 1511:02 AMDec 3112:28 AMDec 3112:28 AMJan 1412:28 AMJan 1412:28 AMJan 292:37 PMJan 292:37 PMFeb 123:54 PMFeb 123:54 PMFeb 282:45 AMFeb 282:45 AMMar 148:55 AMMar 148:55 AMMar 2912:58 PMMar 2912:58 PM4:59 AM4:59 AM6:20 PM6:20 PM5:12 AM5:12 AM4:50 AM4:50 AM6:18 PM6:18 PM4:45 AM4:45 AM7:53 PM7:53 PM7:04 PM7:04 PM5:38 AM5:38 AM5:16 AM5:16 AM7:18 PM7:18 PM7:03 PM7:03 PM6:26 AM6:26 AM7:05 PM7:05 PM6:05 PM6:05 PM6:06 AM6:06 AM6:09 PM6:09 PM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil 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.

The chance that a given day will be muggy in Johannesburg is essentially constant during the summer, remaining within 1% of 1% throughout.

The highest chance of a muggy day during the summer is 2% on February 23.

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.

Humidity Comfort Levels in the Summer in Johannesburg

Humidity Comfort Levels in the Summer in JohannesburgDecJanFeb0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%SpringFallFeb 232%Feb 232%Dec 10%Dec 10%Jan 11%Jan 11%Feb 11%Feb 11%humidhumidcomfortablecomfortabledrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 decreasing during the summer, decreasing from 8.0 miles per hour to 6.5 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.

Average Wind Speed in the Summer in Johannesburg

Average Wind Speed in the Summer in JohannesburgDecJanFeb0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mph14 mph14 mphSpringFallDec 18.0 mphDec 18.0 mphFeb 286.5 mphFeb 286.5 mphJan 17.3 mphJan 17.3 mphFeb 16.8 mphFeb 16.8 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The wind direction in Johannesburg during the summer is predominantly out of the north from December 1 to February 10 and the east from February 10 to February 28.

Wind Direction in the Summer in Johannesburg

Wind Direction in the Summer in JohannesburgNENDecJanFeb0%100%20%80%40%60%60%40%80%20%100%0%SpringFallwesteastnorthsouth
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

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 summer in Johannesburg is reliably fully within the growing season.

Time Spent in Various Temperature Bands and the Growing Season in the Summer in Johannesburg

Time Spent in Various Temperature Bands and the Growing Season in the Summer in JohannesburgDecJanFeb0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%SpringFall100%Jan 15100%Jan 15coldcoolcomfortablewarm
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within 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.

The average accumulated growing degree days in Johannesburg are very rapidly increasing during the summer, increasing by 1,552°F, from 1,524°F to 3,076°F, over the course of the season.

Growing Degree Days in the Summer in Johannesburg

Growing Degree Days in the Summer in JohannesburgDecJanFeb1,500°F1,500°F2,000°F2,000°F2,500°F2,500°F3,000°F3,000°FSpringFallDec 11,524°FDec 11,524°FFeb 283,076°FFeb 283,076°FJan 12,048°FJan 12,048°FFeb 12,606°FFeb 12,606°F
The average growing degree days accumulated over the course of the summer, with 25th to 75th and 10th to 90th percentile bands.

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 essentially constant during the summer, remaining within 0.4 kWh of 7.3 kWh throughout.

The highest average daily incident shortwave solar energy during the summer is 7.7 kWh on December 29.

Average Daily Incident Shortwave Solar Energy in the Summer in Johannesburg

Average Daily Incident Shortwave Solar Energy in the Summer in JohannesburgDecJanFeb0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhSpringFallDec 297.7 kWhDec 297.7 kWhDec 17.4 kWhDec 17.4 kWhFeb 286.9 kWhFeb 286.9 kWhFeb 17.4 kWhFeb 17.4 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

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%).

This report illustrates the typical weather in Johannesburg, 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 Johannesburg.

For each station, the records are corrected for the elevation difference between that station and Johannesburg 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 Johannesburg is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Johannesburg and a given station.

The stations contributing to this reconstruction are:

To get a sense of how much these sources agree with each other, you can view a comparison of Johannesburg and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports and weather stations are provided by AskGeo.com .

Maps are © OpenStreetMap contributors.

Disclaimer

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.

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