Mon, 28 Jul 2014
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 26/13
ALLDAYS 20/11
BEAUFORT WEST 19/04
BELA-BELA 21/09
BETHLEHEM 16/01
BISHO 24/07
BLOEMFONTEIN 18/03
CALVINIA 23/07
CAPE ST LUCIA 20/16
CAPE TOWN 19/11
CLANWILLIAM 23/10
DE AAR 18/03
DURBAN 22/16
EAST LONDON 23/14
ERMELO 17/03
FAURESMITH 18/05
FICKSBURG 15/01
GEORGE 21/08
GRAAF-REINETT 19/04
GRAHAMSTOWN 24/10
HERMANUS 19/11
JOHANNESBURG 17/04
JOUBERTINA 22/09
KIMBERLEY 20/07
KLERKSDORP 20/06
KOMATIPOORT 19/10
KROONSTAD 19/04
LADYSMITH 16/00
LANGEBAAN 22/12
LEPHALALE 20/09
LYDENBURG 17/05
MAFIKENG 20/07
MUSINA 19/12
NELSPRUIT 16/06
NEWCASTLE 19/02
OUDTSHOORN 22/07
PAARL 21/05
PHALABORWA 19/12
PIETERMARITZBURG 19/06
PLETTENBERG BAY 21/12
POLOKWANE 18/08
PORT ALFRED 22/11
PORT ELIZABETH 23/11
PORT ST JOHNS 23/11
POTCHEFSTROOM 18/05
PRETORIA 19/07
QUEENSTOWN 19/03
RICHARDS BAY 21/17
ROBERTSON 21/05
RUSTENBURG 19/06
SASOLBURG 19/06
SKUKUZA 18/11
SOWETO 17/05
SPRINGBOK 24/09
STILBAAI 20/11
SUTHERLAND 19/05
TZANEEN 18/09
ULUNDI 20/11
UMTATA 21/05
UPINGTON 23/09
VEREENIGING 18/05
VREDENDAL 26/11
VRYBURG 20/08
WELKOM 19/06
WITBANK 18/06
WORCESTER 22/05

 

| 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