Radiosonde · twice daily
Cape Town Sounding
The latest weather-balloon profile from Cape Town International Airport, plotted as a Skew-T log-P diagram.
Latest
Thu, 29 Oct, 14:00 SAST (12Z)
Data: University of Wyoming
- Airport surface
- 23.6°C / dew point 14.6°C
- Trigger temperature
- 24.9°C for 500 m
- Thermal top at 26.7°C
- ≈ 580 m
- Cloudbase
- Blue (above thermal top)
Inversions below 6 km
- 327–451 m: +1.4°C
- 505–613 m: +3.0°C
- 790–912 m: +1.2°C
Previous
Thu, 29 Oct, 02:00 SAST (00Z)
Data: Ogimet (decoded TEMP message, fewer levels)
- Airport surface
- 16.8°C / dew point 12.4°C
- Trigger temperature
- 27.6°C for 500 m
- Thermal top at 26.7°C
- ≈ 360 m
- Cloudbase
- Blue (above thermal top)
Inversions below 6 km
- 43–351 m: +6.4°C (surface-based)
- 577–716 m: +1.4°C
Reading the chart. Red is air temperature and blue is dew point. Where the red line leans right with height, that is an inversion (shaded amber). The dashed black line is a thermal rising on the dry adiabat from sea level for Signal Hill; it tops out where it meets the red line.
Limits. This is one balloon at one point near the coast, not your launch. Thermal tops assume a parcel starts at sea level and rises without mixing, so they are an upper estimate for sites well above sea level. The 14:00 (12Z) sounding is paired with the forecast maximum temperature (the warmest of the 08h, 11h, 14h and 17h forecast windows). The 02:00 (00Z) sounding is paired with the 14h forecast temperature and still carries the overnight inversion, so its tops show how far a 2pm parcel would get through that inversion. Cloudbase uses the 125 m per °C temperature/dew-point spread rule from the airport surface dew point. The trigger temperature is the surface temperature needed to reach 500 m above sea level. Use these as a guide next to the forecast, not instead of it.
Source: South African Weather Service launches, station 68816, via the University of Wyoming sounding archive. When Wyoming has not yet ingested a launch, the raw TEMP message from Ogimet is decoded instead; it has fewer levels and slightly coarser dew points. Thermal tops use the two most recent launches.
Thermal tops by site
2026-10-29 forecast, parcel started at sea level. 14:00 column: Thu, 29 Oct, 14:00 SAST (12Z) sounding with the forecast maximum. 02:00 column: Thu, 29 Oct, 02:00 SAST (00Z) sounding with the 14h forecast temperature.
| Site | Forecast max | 14h temp | Top, 14:00 sounding (m ASL) | Top, 02:00 sounding (m ASL) | Cloudbase, 14:00 (m ASL) |
|---|---|---|---|---|---|
| Agulhas | 19.6°C | 19.6°C | Below trigger | Below trigger | – |
| Bains Kloof | 29.8°C | 29.8°C | 740 | 670 | – |
| Barrydale | 29.4°C | 29.4°C | 670 | 650 | – |
| Betties Bay | 22.2°C | 22.2°C | Below trigger | Below trigger | – |
| Brenton View | 20.2°C | 20.2°C | Below trigger | Below trigger | – |
| Brenton-on-Sea | 15.6°C | 15.6°C | Below trigger | Below trigger | – |
| Buffalo Bay | 16.7°C | 16.7°C | Below trigger | Below trigger | – |
| Caledon | 30.5°C | 30.5°C | 810 | 700 | – |
| Ceres Mountain | 24.1°C | 24.1°C | Below trigger | Below trigger | – |
| Constantiaberg East | 25.4°C | 25.4°C | 540 | Below trigger | – |
| Constantiaberg West | 25.2°C | 25.2°C | 520 | Below trigger | – |
| Dana Bay | 22.6°C | 22.6°C | Below trigger | Below trigger | – |
| Devils Peak | 30.7°C | 30.7°C | 820 | 710 | – |
| Dolphin Beach | 27.4°C | 27.4°C | 590 | Below trigger | – |
| Du Toits Farm | 30.6°C | 30.6°C | 820 | 710 | – |
| Du Toits Kloof | 28.7°C | 28.7°C | 610 | 620 | – |
| Franschhoek | 28.1°C | 28.1°C | 600 | 580 | – |
| Gansbaai | 28.1°C | 28.1°C | 600 | 580 | – |
| George Peak | 25.2°C | 24.1°C | 520 | Below trigger | – |
| Gerrickes Point | 16.9°C | 16.9°C | Below trigger | Below trigger | – |
| Glen Club | 22.9°C | 22.9°C | Below trigger | Below trigger | – |
| Gordons Bay | 26.0°C | 24.3°C | 560 | Below trigger | – |
| Gordons Bay Octopus Rd | 27.6°C | 26.4°C | 590 | Below trigger | – |
| Groot Kanonkop | 26.1°C | 26.1°C | 570 | Below trigger | – |
| Gydo Pass | 29.3°C | 29.3°C | 660 | 650 | – |
| Hermanus | 26.0°C | 26.0°C | 560 | Below trigger | – |
| Kardoesie | 31.1°C | 31.1°C | 840 | 890 | – |
| Katbakkies | 29.1°C | 29.1°C | 630 | 640 | – |
| Kirstenbosch | 23.7°C | 22.8°C | Below trigger | Below trigger | – |
| Kleinkrantz | 18.8°C | 18.8°C | Below trigger | Below trigger | – |
| Kleinmond | 22.9°C | 22.9°C | Below trigger | Below trigger | – |
| Kommetjie | 21.0°C | 20.6°C | Below trigger | Below trigger | – |
| Koringberg | 31.5°C | 31.5°C | 860 | 990 | – |
| Langebaan Dunes | 20.4°C | 20.3°C | Below trigger | Below trigger | – |
| Lions Head | 25.4°C | 25.4°C | 540 | Below trigger | – |
| Llandudno | 24.1°C | 24.1°C | Below trigger | Below trigger | – |
| Macassar | 23.4°C | 22.1°C | Below trigger | Below trigger | – |
| Map of Africa | 22.1°C | 22.1°C | Below trigger | Below trigger | – |
| Matroosberg | 23.0°C | 23.0°C | Below trigger | Below trigger | – |
| Meerendal GH | 26.9°C | 26.9°C | 580 | Below trigger | – |
| Meerendal HNF | 27.3°C | 27.3°C | 590 | Below trigger | – |
| Misty Cliffs | 21.9°C | 21.9°C | Below trigger | Below trigger | – |
| Muizenberg Vlei | 23.1°C | 22.7°C | Below trigger | Below trigger | – |
| Noordhoek | 25.9°C | 25.9°C | 560 | Below trigger | – |
| Noordhoek Pole Yard | 25.0°C | 25.0°C | 510 | Below trigger | – |
| Ou Kaapse Weg | 24.1°C | 23.4°C | Below trigger | Below trigger | – |
| Paarl Cricket Club | 33.9°C | 33.9°C | 1200 | 1590 | – |
| Paarl Rock | 30.4°C | 30.4°C | 810 | 700 | – |
| Paarl Sports Field | 35.1°C | 35.1°C | 1590 | 1930 | – |
| Paradise Ridge | 19.1°C | 19.1°C | Below trigger | Below trigger | – |
| Piekiniers Mast | 31.2°C | 31.2°C | 850 | 910 | – |
| Piesangvallei | 24.8°C | 24.8°C | Below trigger | Below trigger | – |
| Piketberg | 29.4°C | 29.4°C | 670 | 650 | – |
| Porterville: Dasklip Pass | 30.4°C | 30.4°C | 810 | 700 | – |
| Porterville: Pampoenfontein | 30.1°C | 30.1°C | 780 | 680 | – |
| Radloff Park | 29.9°C | 29.9°C | 750 | 680 | – |
| Robertson | 25.2°C | 25.2°C | 520 | Below trigger | – |
| Rusty Gate | 28.1°C | 28.1°C | 600 | 580 | – |
| Saldanha | 17.3°C | 17.3°C | Below trigger | Below trigger | – |
| Scarborough | 20.0°C | 20.0°C | Below trigger | Below trigger | – |
| Sea Point Promenade | 22.5°C | 22.4°C | Below trigger | Below trigger | – |
| Sedgeview | 23.7°C | 23.7°C | Below trigger | Below trigger | – |
| Signal Hill | 26.7°C | 26.7°C | 580 | Below trigger | – |
| Sir Lowrys Pass | 28.4°C | 28.4°C | 600 | 600 | – |
| St. James | 21.4°C | 20.9°C | Below trigger | Below trigger | – |
| Strandfontein | 17.5°C | 17.5°C | Below trigger | Below trigger | – |
| Swartberg | 27.2°C | 27.2°C | 580 | Below trigger | – |
| Swellendam | 29.1°C | 29.1°C | 630 | 640 | – |
| Table Mountain | 27.0°C | 27.0°C | 580 | Below trigger | – |
| The Views | 27.7°C | 27.7°C | 590 | 520 | – |
| TM Gulley | 27.3°C | 27.3°C | 590 | Below trigger | – |
| TM Maclears | 25.2°C | 25.2°C | 520 | Below trigger | – |
| Uplands | 28.4°C | 27.4°C | 600 | Below trigger | – |
| Wilderness Hotel | 20.8°C | 20.8°C | Below trigger | Below trigger | – |