A berg wind is caused by a high altitude inland high pressure, usually in winter, on the cold, dry central plateau areas above the great escarpment, coupled with lower pressures at the coast. The wind flows down the escarpment and is heated by compression. The temperature rise can be considerable and occurs over a short period. This hot, dry wind is offshore in most parts of Cape Town and it is usually followed by cool onshore winds with low cloud, fog and drizzle, and is often associated with the approach of a cold front from the west in winter, which may bring strong westerly winds and substantial frontal rain.