Tropical Storm Otto has developed in the western Caribbean and, according to the National Hurricane Centre, could develop into a hurricane by Wednesday.

In yet another nod towards climate change, the storm has developed over very warm waters – sea surface temperatures of 29C are about 1C above average – and a tropical system this far south of the region is a rare event.

If Otto does become a hurricane, and makes landfall across southern Nicaragua or even Costa Rica, it could become the southernmost hurricane landfall on record in Central America.

Otto threatens to bring life-threatening flash floods and mudslides to parts of Nicaragua, Costa Rica and Panama.

The storm is about 500km southeast of Nicaragua and is staggering towards the coast at around 4km/h.

The system has sustained winds of 95km/h, but it is expected to strengthen over the next 24 hours.

Torrential downpours

Some computer models, including the UKMET and The European Centre for Medium-Range Weather Forecasts, do not predict strengthening beyond a strong tropical storm or perhaps a weak hurricane.

Either way, torrential downpours are likely to be the main hazard.

The slow movement of the storm means that vast amounts of rainfall are expected across the area.

Accumulations of up to 150mm of rain are probable across a wide area, but totals could approach 250 to 375mm of rain over the higher ground.

The widespread flooding is likely by Thursday as Otto approaches the Caribbean coast near the border of Nicaragua and Costa Rica, where landfall is currently expected on Thursday afternoon or evening.

Current projections then see the storm moving into the eastern Pacific on Friday as a tropical depression.