The main physical feature which impacts on the weather is the complex system of folded mountains – most of them rising above 600m, the coastal plains and the mountainous Cape Peninsula.
In summer, the outstanding feature of the weather is the wind known as the Cape southeaster. It blows strongly for several days without interruption. The normal southeaster is associated with fine weather. A heavy white cloud forms the famous tablecloth on Table Mountain. While humidity is rarely uncomfortable, temperatures can rise into the high 30's for short periods.
Stormy weather normally occurs in midwinter. Unstable waves on polar fronts develop into depressions and move ±200km south-west of Cape Town. The wind is generally northerly and north-westerly with gale strength. The rain is often quite heavy, with a low cloud ceiling and poor visibility.
The annual rainfall is 600mm on average, but arising from the influences of the mountain chains, some places receive over 2 500mm annually. Snow may fall in the mountains at almost any time between April and August. The average number of occasions when falls occur is about five a year.
The Cape's weather is really never too hot, nor too cold, and even midwinter offers stunningly clear and invigorating days which are best described as "champagne weather". Visitors should always take advice from locals, because if its pouring with rain or there are gale force winds in one area, it could be beach weather less than 10km away. That's what this phenomenal topography produces!
And if inclement weather ever does become an issue, there is so much else to do.
Average from 1961 to 1990 at Cape Town International Airport If there has been a change in global weather patterns, subjectively one must say there has been global warming with less rainfall... and more care needs to be taken against UV radiation in summer.
Ave Rainfall mm
Ave Rainfall days
No. clear days (<2/8 cloud)
No. cloudy days (>6/8 cloud)
Ave. % of Possible Sunshine
Ave. Max. Temp °C
Ave. Min. Temp °C
January
15
5,5
14
1
76
26,1
15,7
February
17
4,6
13
2
79
26,5
15,6
March
20
4,8
12
2
77
25,4
14,2
April
41
8,3
1
4
70
23,0
11,9
May
69
11,4
7
7
63
20,3
9,4
June
93
13,3
8
6
58
18,1
7,8
July
82
11,8
9
8
63
17,5
7,0
August
77
13,7
8
6
62
17,8
7,5
September
40
10,4
7
7
64
19,2
8,7
October
30
8,7
8
4
69
21,3
10,6
November
14
4,9
9
4
74
23,5
13,2
December
17
6,2
10
2
75
24,9
14,9
Totals/Averages
515
103
106
53
69
22,0
11,4
Source: "The Weather & Climate of the Extreme South Western Cape" – South African Weather Bureau – Department of Environmental Affairs & Tourism, 1996. National Library of SA reference number: AP 1996-103.
