A powerful cut-off low is driving severe thunderstorms across parts of South Africa on Friday, September 4, with the South African Weather Service issuing an Orange Level 5 warning for the most exposed areas of the Northern Cape.
The highest warning covers east-central parts of the Northern Cape, where thunderstorms could produce damaging winds, hail, excessive lightning and torrential downpours capable of flooding settlements, roads and bridges.
SAWS warned that trees could be brought down, structures damaged and municipal services disrupted, particularly where lightning or strong convective wind gusts affect electricity and communications infrastructure.
BREAKING: A powerful cut-off low is battering South Africa. Cape Town faces 82 km/h gusts under a Yellow Level 2 warning, while Durban braces for 90 km/h winds and the Northern Cape faces an Orange Level 5 storm alert. pic.twitter.com/ZPiKpTotXV
— HINT News (@9415st) September 4, 2026
Five Northern Cape municipalities were included in the Orange Level 5 warning, which remains valid through Friday. A broader Yellow Level 4 severe-thunderstorm warning extends across central and eastern parts of the province, western Free State, the extreme west of North West and southern KwaZulu-Natal.
Severe weather stretches across several provinces
The Northern Cape is at the center of the most significant thunderstorm threat, but the unsettled weather pattern extends across a large portion of South Africa.
Yellow Level 2 severe-thunderstorm warnings also cover parts of the Free State, North West, southern Gauteng and southwestern Mpumalanga, where localized hail and wind damage, falling trees and disruption from intense lightning are possible.
Farther south and west, the same system is producing a different set of hazards.
Damaging-wind warnings cover parts of the Northern Cape, Western Cape and KwaZulu-Natal, while dangerous winds and waves are affecting sections of the coastline. Between Alexander Bay and Plettenberg Bay, strong winds and rough seas could disrupt ports and create hazardous conditions for vessels.
Parts of the Eastern Cape are also under warnings for disruptive rainfall, with localized flooding possible in settlements, low-lying areas and along vulnerable roads and bridges.
The Western Cape has already recorded some impacts from strong winds. Cape Town disaster management reported damage to informal homes, while strong crosswinds temporarily forced the closure of the Huguenot Tunnel.
Why is the weather so severe?
At the heart of the event is a cut-off low, a pool of unusually cold air in the middle and upper atmosphere that has become separated from the main belt of westerly winds.
These systems can produce particularly volatile weather across southern Africa.
As the cold air aloft moves over comparatively warmer and moisture-bearing air closer to the surface, the atmosphere becomes increasingly unstable. Rising air can then accelerate rapidly through the atmosphere, supporting deep cumulonimbus clouds and powerful thunderstorms.
Strong upper-level forcing associated with the low is providing additional lift, while changes in wind speed and direction with altitude create vertical wind shear capable of organizing thunderstorms and allowing them to persist longer.
The combination raises the risk of large hail, intense lightning, damaging wind gusts and short periods of very heavy rain.
Rainfall coverage across some of the most affected areas of the Northern Cape could reach around 80 percent on Friday.
Cold, wind and rain behind the thunderstorms
The cut-off low is also pulling significantly colder air across western and southern South Africa.
Very cold, wet and windy conditions are expected over parts of Namakwa and the interior of the Western Cape, while unusually cold conditions extend into high-lying areas of the Eastern Cape.
In some elevated locations, daytime temperatures may struggle to rise above 10°C (50°F).
The result is an unusually complex early-spring weather event, with severe thunderstorms and hail over the interior occurring alongside damaging coastal winds, disruptive rain and sharply colder temperatures farther south.
Severe storm threat continues into the weekend
The weather threat will not disappear immediately Friday night.
As the cut-off low continues moving eastward, severe thunderstorms are expected to shift across the interior during Saturday. SAWS has maintained an Orange Level 5 severe-thunderstorm warning over central parts of the Northern Cape for September 5, with additional warnings extending into North West and the Free State.
Residents in warned areas are being urged to avoid flooded roads, secure loose outdoor objects and remain indoors during intense lightning or hail.
The exact hazards will change as the system crosses the country, but the cut-off low is expected to keep large parts of South Africa unsettled into the weekend.
