Thu, 29 Sep 2016
METROCAST | 




SA REGIONAL




INFORMATION




You are in: Weather > SA regional > Ecucation


BERGWIND

Bergwind is the South African name for fohn wind or mountain wind. It is a hot, dry wind that blows from the interior of South Africa to the coast and usually is blustery. Most people find it rather unpleasant. It can be mild at times blowing at about 10km/h, but sometimes it can be really strong and may gust up to 100km/h causing some structural damage to buildings and uprooting trees.

FORMATION

Bergwinds usually occur when a strong high pressure exists south or south-east of the country and when a high pressure is also situated over the country. These conditions usually only occur in winter, but sometimes in summer too, hence bergwinds are mainly a autumn-winter-spring phenomemon.

Since air rotates anti-clockwise around a high pressure in the southern hemisphere the wind direction to the north of the high pressure will be easterly or north-easterly, especially along the west coast of southern Africa. The bergwinds will usually start blowing along the Namibian coast and the first indication of bergwinds is a rise in temperature, sometimes this rise can be rapid. In winter of 1985 in CT, the temperature rose from 3C at 07:00 in the morning to 27C by 07:35 that SAME morning. This is not a common occurrence, but rather an extreme case.

Since air in a high pressure descends and warms up as it descends it stands to reason that the off-shore winds will be warm to hot and the temperature will usually rise about 10 degrees Centigrade from the interior of SA to the coast. So the temperate at Upington may be 20C, while at Alexander Bay it may be over 30C.

At the same time a coastal low will develop along the coast. Off-shore flow ahead of the coastal low is usually easterly to north-easterly in direction along the west coast and north-westerly along the east coast. Humidities are usually very low, sometimes as low as 5%, usually between 10-40%. The temperatures vary from 25C to 35C in winter and over 40C in summer. Behind the coastal low the wind is on-shore and usually north-westerly to south-westerly in direction. It is cool and moist and usually associated with fog.

The coastal low moves down the west coast and around the Cape Point and then up the east coast of South Africa until it fills up near Maputo in Mozambique. The bergwinds obviously follow the same pattern. The highest official temperatures recorded in South Africa (51.5 C) was recorded one summer during a bergwind occurring along the Eastern Cape coastline.

The bergwinds are usually followed by a cold front in winter.

Click on the minimized diagram below to view an enlarged image of the typical coastal low and bergwinds.


Click to view a larger image.

[ back ]

Search
Goodstuff



Goodstuff
ALEXANDER BAY 20/09
ALLDAYS 32/15
BEAUFORT WEST 22/05
BELA-BELA 29/12
BETHLEHEM 24/03
BISHO 18/08
BLOEMFONTEIN 25/04
CALVINIA 20/07
CAPE ST LUCIA 24/19
CAPE TOWN 18/11
CLANWILLIAM 21/08
DE AAR 23/05
DURBAN 20/15
EAST LONDON 19/12
ERMELO 24/09
FAURESMITH 24/07
FICKSBURG 24/01
GEORGE 16/09
GRAAF-REINETT 21/05
GRAHAMSTOWN 19/08
HERMANUS 15/09
JOHANNESBURG 26/10
JOUBERTINA 14/06
KIMBERLEY 26/05
KLERKSDORP 29/10
KOMATIPOORT 27/19
KROONSTAD 27/06
LADYSMITH 28/09
LANGEBAAN 17/11
LEPHALALE 32/16
LYDENBURG 25/10
MAFIKENG 31/12
MUSINA 33/17
NELSPRUIT 25/11
NEWCASTLE 29/11
OUDTSHOORN 20/08
PAARL 17/08
PHALABORWA 26/15
PIETERMARITZBURG 16/11
PLETTENBERG BAY 16/11
POLOKWANE 29/11
PORT ALFRED 18/12
PORT ELIZABETH 18/12
PORT ST JOHNS 19/14
POTCHEFSTROOM 30/09
PRETORIA 27/11
QUEENSTOWN 17/07
RICHARDS BAY 22/18
ROBERTSON 20/10
RUSTENBURG 29/12
SASOLBURG 28/10
SKUKUZA 29/16
SOWETO 25/10
SPRINGBOK 26/08
STILBAAI 17/11
SUTHERLAND 16/03
TZANEEN 24/14
ULUNDI 24/12
UMTATA 18/09
UPINGTON 28/09
VEREENIGING 29/09
VREDENDAL 17/06
VRYBURG 31/10
WELKOM 27/07
WITBANK 25/08
WORCESTER 21/10

 

| DISCLAIMER | FEEDBACK | ABOUT US | ADVERTISING | CONTACTS | SERVICES & PRODUCTS |

©COPYRIGHT 1995-2010, CUSTOMWEATHER,INC
San Francisco, California, USA
Your use of this site constitutes your acceptance of
the LEGAL RESTRICTIONS AND TERMS OF USE