Hurricane Clarissa only appears in the movie canon. In the novels or Trespasser Site B is abandoned because InGen was bankrupt, but, in the movie canon InGen survived the downfall of the Park and therefore an explanation was needed as to why InGen would leave the dinosaurs behind on the island.
- "Hurricane Clarissa wiped out Site B. Call it an act of God. We had to evacuate and the animals were released to mature on their own in the wild. Life will find a way, as you once so eloquently put it. For four years now I’ve fought to keep them safe from human interference."
In the script of the movie another quote from Hammond about the Hurricane is found:
- "The hurricane seemed like a disaster at the time, but now I think about it was a blessing, nature’s way of freeing those animals from their human confines. Of giving them another chance to survive, but this time as they were meant to without man’s interference."
In Hammond's script for Trespasser: Jurassic Park, another quote also indirectly mentions Hurricane Clarissa:
Economics! The bankruptcy struck Site B with more force than the hurricane.
When Hurricane Clarissa hit Isla Sorna is a subject of debate. It obviously took place after the Isla Nublar Incident because the animals of the Park came from Isla Sorna. In the movie Hammond says: "For four years now I’ve fought to keep (the dinosaurs) safe from meddling". No dates are mentioned in the movies but most data suggests that the Incident at the Park took place in 1993 and the events of The Lost World in 1997 (see this article for more details). From this data and the quote of Hammond most fans have concluded that Hurricane Clarissa struck Isla Sorna more or less directly after the Isla Nublar Incident. Some fans have suggested that the hurricane could be seen in the film Jurassic Park at one of the computer screens. A storm is on a computer screen showing the island when Robert Muldoon is talking to the weather station about a storm not slowing down, or changing course. This suggestion, however, is impossible when critically analyzed. Muldoon stated the hurricane that would inevitably hit Isla Nublar was "75 miles west" of the island, indicating it was heading east; Isla Sorna is 87 miles southwest of Isla Nublar. This means that the hurricane would have needed to have hit Sorna prior to hitting Nublar, but factually we know Clarissa collided with Sorna after Nublar was already damaged.
In the original script, Hammond says: "About twenty-four months ago Hurricane Clarisse wiped out Site B." In this case the hurricane struck the island in 1995. Because this sentence never made it into the movie, most fans don't regard it as canon. It could be that this sentence was only removed due to spacing, and that the storm was still meant to take place in 1995.
It is also said that the 1995 date is in conflict with the fact that Hammond tried to keep the dinosaurs safe from meddling for four years. But it is shown in the first movie that Hammond doesn't endorse his park anymore, it could be that immediately after the incident Hammond let the dinosaurs of Isla Sorna roam free but that he had still InGen personnel on the island because he didn't believe the dinosaurs would survive on their own (for instance, due to the lysine contingency). But, when the Hurricane struck the island he had to evacuate the island.
In Trespasser's script, Hammond states "The bankruptcy struck Site B with more force than the hurricane". This could possibly be referencing Hurricane Clarissa, considering the Trespasser canon was based on the film canon. This would also imply that Clarissa hit Site B between August and October 1989 (after the InGen Incident, but before the bankruptcy declaration on October 3). The Emily was also most likely beached by this storm.
Islands in the region have been under government quarantine since June 1995 - Coastal patrols subsidized via InGen funding initiative
It could be that this 1995 date was inspired by the 1995 date for Hurricane Clarissa from the script of The Lost World. Until the hurricane, InGen had full control over the island; after the storm, all control was gone and it would be in InGen's interest to keep the islands under quarantine.