Mon, 30 Mar 2015
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 25/13
ALLDAYS 21/18
BEAUFORT WEST 30/14
BELA-BELA 24/17
BETHLEHEM 23/10
BISHO 28/16
BLOEMFONTEIN 25/13
CALVINIA 29/15
CAPE ST LUCIA 24/-66
CAPE TOWN 27/17
CLANWILLIAM 33/18
DE AAR 26/12
DURBAN 22/19
EAST LONDON 25/19
ERMELO 20/14
FAURESMITH 26/11
FICKSBURG 23/09
GEORGE 25/17
GRAAF-REINETT 29/13
GRAHAMSTOWN 29/16
HERMANUS 29/16
JOHANNESBURG 21/13
JOUBERTINA 30/14
KIMBERLEY 29/12
KLERKSDORP 24/13
KOMATIPOORT 23/20
KROONSTAD 24/13
LADYSMITH 24/14
LANGEBAAN 26/15
LEPHALALE 21/18
LYDENBURG 20/15
MAFIKENG 25/14
MUSINA 21/19
NELSPRUIT 19/16
NEWCASTLE 22/14
OUDTSHOORN 34/17
PAARL 32/18
PHALABORWA 24/19
PIETERMARITZBURG 23/14
PLETTENBERG BAY 23/17
POLOKWANE 21/16
PORT ALFRED 27/20
PORT ELIZABETH 24/19
PORT ST JOHNS 24/18
POTCHEFSTROOM 25/13
PRETORIA 24/15
QUEENSTOWN 27/13
RICHARDS BAY 24/21
ROBERTSON 32/15
RUSTENBURG 25/16
SASOLBURG 25/12
SKUKUZA 24/19
SOWETO 22/12
SPRINGBOK 21/12
STILBAAI 27/17
SUTHERLAND 27/13
TZANEEN 21/16
ULUNDI 21/17
UMTATA 26/16
UPINGTON 28/16
VEREENIGING 25/12
VREDENDAL 31/16
VRYBURG 26/14
WELKOM 25/14
WITBANK 20/14
WORCESTER 32/17

 

| 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