In what scientists say is a glimpse into Tasmania's climate future, water temperatures off the state's east coast have been up to 4 degrees Celsius above average for more than 100 days.

As well as drought, fire and flood this summer, the marine environment began warming up on December 8 last year and the heatwave is still going.

"Tasmanian waters have been incredibly hot," said CSIRO research scientist Dr Alistair Hobday.

"Since satellite records began in the early 1980s we've never seen an event like this."

Dr Hobday said the marine heatwave was caused, in part, by the strong East Australian Current bringing warm waters south.

El Nino has also contributed to warmer temperatures, but he said the warming climate was playing a role.

"We can't explain it just on the basis of variability alone," he said.

Window into state's climate future

The heatwave is on top of other damaging environmental conditions experienced this summer — drought, fire and flood have plagued the state.

"Tasmania's had perhaps a window into the future this summer," said Dr Hobday.

"This summer Tasmania has experienced really dry conditions that led to bushfires in the north of the state.

"Then we had really strong periods of rainfall, massive flooding in parts of Tasmania, and then off our coast this marine heatwave was occurring at the same time — three really surprising environmental things in Tasmania."

Dr Hobday said anecdotally, many Tasmanians noticed the warm summer, but the data was now backing that up.

"It's only now that we've started to analyse the data, we've really realised what a dramatic event this has been," he said.

The warmer waters are expected to impact on the state's marine life.

"Some animals will be stressed and will die but we'll see new species come into Tasmanian waters," Dr Hobday said.