"Return to the safest shelters before the hurricane arrives, and avoid areas which could flood," police in the French part of St Martin pleaded, only three days after it was ravaged by Irma.
Jose, a Category Four storm, will bring heavy rains and winds of 130 to 150 kilometres per hour, meteorologists said.
But it is possible the storm could miss the islands of St Martin and St Barts when it hits later today, and veer about 100 kilometres to the north.
Irma left at least 12 dead and hundreds injured across the island, and with the clean-up barely begun, authorities are struggling to get aid to the stricken population.
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When the hurricane hit on Wednesday, it ripped off roofs and uprooted trees, tossing cars and boats about like matchsticks.
Debris still clogs the streets, many homes are uninhabitable, communications are still down and tens of thousands are without food, water or power.
Dutch Navy commander Peter Jan de Vin said it was "an illusion" that islanders could prepare properly for Jose's arrival.
On the southern Dutch half of the island, 70 per cent of the infrastructure has been destroyed in the storm, officials said.
Sint Maarten's Prime Minister William Marlin told RTL television that repairs could take months. "We are expecting a huge drop in tourism. It will have a huge impact on our economy," he said.
At the only fully-operational airport, located on the French side, exhausted women including one with a newborn baby, children and the elderly waited for flights out to nearby Guadeloupe or even mainland France.
"The atmosphere is grim. People are walking around with weapons," De Vin said, while insisting that Dutch troops were "getting more of a grip on the situation".
One Dutch holidaymaker told the Telegraaf tabloid that he and about 50 guests had barricaded themselves into their hotel in Philipsburg for safety.
"Groups of several people, sometimes whole families, are roaming the streets with knives and firearms," said Dick Algra, 61.
"Shops are being broken into and everything carted away."
"The toilets, unfortunately, can't be flushed as there is no water. So we have brought sea water in a large container," he told Dutch broadcaster NOS. Other hotels looked like a "bomb had gone off".
In a race against time, Dutch and French troops and aid workers have been sent to the region.
Photographs showed lines of people, some standing in the sea, helping to unload aid packages hand-to-hand at the damaged port.
The French interior ministry said some 1,105 people had been deployed including police, troops, firemen, health workers, and electrical engineers.
Authorities on the British Virgin Islands and Anguilla, both self-governing British territories, were also racing to clean up the devastation before the arrival of Hurricane Jose.
Britain today confirmed six deaths in its Caribbean territories as Irma passed.
"We're trying to get rid of most of the debris seeing as we're going to be facing Jose in a few hours," said Sherrie Brooks, an officer with the Royal Anguilla Police Force.