The Samoa Meteorology Division has issued a heavy rain advisory for all of Samoa and says a low pressure system within the vicinity continues to impact on the weather.

The Severe Weather Information was issued by the Samoa meteorology Division on Tuesday evening and emphasised that heavy rain advisory is now in effect for the whole country.

"A moderate southeast to east wind flow continues to prevail over the group, maintaining cloudy periods with isolated showers and few thunderstorms," the Samoa Meteorology Division statement reads.

"Meanwhile, a trough of low pressure now lies within the vicinity of Samoa. The system is expected to provide isolated to scattered rain with brief heavy falls and a few thunderstorms possible later tonight. Therefore heavy rain advisory remains for all land areas of Samoa."

Potential impacts of the weather include heavy downpour with poor visibility, foggy and slippery roads over mountain passes and ranges according to the advisory. Other potential impacts include pooling near roadsides and waterways.

The Meteorology Division has forecast that from Wednesday through to Monday, the trough will remain within the forecast zone until Wednesday with the broad area of instability persisting until this system sinks just south by Thursday. 

"Expect winds to swerve more northerly by Friday with increasing wind strength on Saturday into Sunday," the statement reads.

"These conditions maintain wet and unstable weather for Samoa. Additionally, an upper trough may linger south with a divergence to remain over our area. 

"Moreover, a low-pressure system is forecast to develop northeast of the Fiji group as of this period forcing rainfall activities further south and away from the islands in the latter part of the outlook."

The marine outlook was also no different with the Meteorology Division forecasting wave and swell heights remain below 2 metres as was observed from available wave buoys and altimeters. 

"Fresh winds along with a high-pressure system to the southeast may slightly increase wave heights above 2 metres for Monday with light winds to impact the long term forecast for marine waters as a trough would impact all marine waters of Samoa," the statement reads.