Barometric pressure in Johannesburg
Beneath its daily wave, pressure has been rising slowly. It stands 2 hPa higher than it did at this time yesterday. It keeps rising until tomorrow morning.
Sea level reading, as of 16:00 local time. A barometer in Johannesburg itself reads about 840 hPa.
The past week and the days ahead
The shaded part shows the days already gone. The thicker line is the forecast. The thin grey line is the average over a whole day, so you can see where pressure is heading under the daily up and down.
The week ahead
Each day at a glance: how far pressure moves, and the low and high it reaches.
Rises steadily through the day.
25° / 11°low 1022 · high 1027 hPa
Rises first, then falls away in the morning.
23° / 10°low 1022 · high 1030 hPa
Eases down slowly through the day.
24° / 10°low 1019 · high 1024 hPa
Falls first, then climbs in the evening.
24° / 12°low 1020 · high 1027 hPa
Edges up slowly through the day.
20° / 10°low 1026 · high 1031 hPa
Falls steadily through the day.
21° / 9°low 1023 · high 1031 hPa
Falls quickly, most of it in the morning.
21° / 10°low 1019 · high 1026 hPa
Hour by hour
| Hour | Weather and temperature | Rain (mm) | Pressure (hPa) |
|---|---|---|---|
| 00:00 |  16° | 1023 | |
| 01:00 | 15° | 1023 | |
| 02:00 | 14° | 1023 | |
| 03:00 | 13° | 1023 | |
| 04:00 | 12° | 1023 | |
| 05:00 | 11° | 1024 | |
| 06:00 | 11° | 1025 | |
| 07:00 | 12° | 1025 | |
| 08:00 | 14° | 1026 | |
| 09:00 | 17° | 1026 | |
| 10:00 | 20° | 1025 | |
| 11:00 | 23° | 1025 | |
| 12:00 | 24° | 1024 | |
| 13:00 | 25° | 1023 | |
| 14:00 | 25° | 1022 | |
| 15:00 | 25° | 1022 | |
| 16:00 | 24° | 1022 | |
| 17:00 | 23° | 1022 | |
| 18:00 | 21° | 1023 | |
| 19:00 | 19° | 1024 | |
| 20:00 | 17° | 1025 | |
| 21:00 | 15° | 1026 | |
| 22:00 | 14° | 1026 | |
| 23:00 | 13° | 1027 |
Biggest change: Wednesday, up 5 hPa.
The highest reading, about 1030 hPa, comes tomorrow morning; it falls from there.
Johannesburg has a strong daily rhythm: pressure swings about 5 hPa between a regular low and high, at almost the same hours each day. Most of what the graph shows is that daily wave, which is why the change since yesterday says more here than the change over a few hours.
Johannesburg sits 1734 m above sea level, so a barometer in the city reads about 182 hPa lower than the sea-level figure. A home station set to the local reading should show about 840 hPa as of 16:00.
The hours already past are the model's record of each hour as it passed, anchored to real observations, though not a reading from an instrument in Johannesburg.
About Johannesburg
Johannesburg's pressure is mostly about how high the city sits. At about 1,749 m on the Highveld, the air above the city presses down with only around 835 hPa. The sea-level values published here therefore run some 192 hPa higher than anything a local instrument will show. The weather adds little on top of that. Sharp day-to-day changes occur only about three times a year, and the typical daily shift is under 2 hPa. What does change, slowly, is the season: the average climbs to about 1025 hPa in the dry July winter and eases back to about 1015 in January.
Sources: WikipediaERA5 reanalysisElevation: Copernicus DEM via Open-Meteo
Cities nearby
Open one to see its pressure, or search for your own city at the top of the page.
Wondering if this weather is normal? See what the weather in Johannesburg has done since 1940, on our sister site 
weatherjourney.com.
Common questions
What is a normal barometric pressure?
Near 1013 hPa at sea level; the exact standard figure, 1013.25 hPa, is the same as 760 mmHg, 29.92 inHg or 101.3 kPa. Anything between roughly 1000 and 1025 hPa is ordinary. Which way it is going matters far more than the number itself.
Why does my own barometer show a different number?
Usually altitude, and sometimes the instrument itself. Weather services correct readings to what they would be at sea level, so that cities can be compared. The figure for Johannesburg, which stands 1734 m above sea level, is in the note above: about 182 hPa below the sea-level reading. If your barometer is already set to sea level and still reads slightly differently, that is the setting on the instrument rather than the weather.
Is a millibar the same as a hectopascal?
Yes. One millibar and one hectopascal are exactly the same amount of pressure, so 1013 mbar and 1013 hPa mean the same thing. The name changed; the number did not.
Does falling pressure mean rain?
Not by itself. Away from the tropics, falling pressure usually means a low is approaching, and lows carry the fronts that bring cloud and rain, so the two often arrive together. But a shallow fall can pass with nothing more than cloud, and rain falls under steady pressure too. The graph tells you a system is on the way, not how wet it will be. The week ahead, just above, shows the rain forecast beside the pressure.
