The following statistics are available from an article by Paul Simons in The Times on 27th December 2017:
Ten consecutive storms reached hurricane status; this is the first time it has happened since 1893. These storms included two category 5 hurricanes, Irma and Maria, the first time this has happened in ten years.
Hurricane Irma’s strongest winds (185mph) broke the record for wind-speed intensity for an Atlantic hurricane outside the Gulf of Mexico and the Caribbean. Irma also maintained its peak intensity for 37 hours, a record for a cyclone anywhere in the world; the previous record was 24 hours, set by Typoon Haiyan in the Philippines in 2013.
Hurricane Harvey rained more heavily than any hurricane ever recorded in US history. About 1,640mm (64.6″) fell in one location in Texas and an estimated 127 billion tonnes of rain fell in total in the state — so much that it compressed the Earth’s crust by roughly 2cm.
Three of the largest hurricanes hit land at their peak intensity, causing huge devastation. Much of the Caribbean lies in ruins in the aftermath of both Hurricane Irma and Hurricane Maria; the island of Barbuda was so devastated that it is uninhabited for the first time in 300 years. See:
Devastation in Barbuda after Hurricane Irma hit the island
Puerto Rica was hit by Hurricane Maria and the number of deaths there is estimated to be over 1,000. It also affected power and water supplies.
The entire hurricane season in the US is reckoned to have been the most destructive in history, taking historical inflation into account, with damage totalling an estimated $206 billion (£154 billion).
Now, a recent article by Eleanor Ainge Roy in The Guardian reports that there are calls for a revision of the scale used to measure hurricanes. Currently, a category 5 hurricane is the worst, describing near-total destruction. But climate scientists meeting at a conference in the New Zealand city of Wellington have floated the idea of creating a category six to reflect the increasing severity of tropical cyclones in the wake of warming sea temperatures and climate change.
New research, published in Nature, shows that rising global temperatures could be causing tropical storms to slow down, allowing them more time to unleash heavy rainfall once making landfall. The research found that the speed at which they travel across the Earth has slowed by an average of 10% over the past 70 years, with the speed of storms originating in the Western North Pacific falling by 30%. An example of this effect was seen during Hurricane Harvey, which stalled over Houston, releasing 100cm of rain in just three days.