There's little sign of a let-up in this year's unusually active storm season with another two typhoons forming in the north-western Pacific.

Typhoon Goni has been upgraded to a category-4 typhoon and is forecast to reach super typhoon strength later on Monday as it moves to the northwest of Guam. That island is reported to have received about 250 millimetres of rain from the event.

Twin typhoons spin in the western Pacific, far to Australia's north. Credit:Himawari-8

The storm is likely to see sustained winds peak at about 150 knots (277 km/h) on Tuesday, with gusts reaching 180 knots (333 km/h), according to the Joint Typhoon Warning Centre.

Taiwan lies in the current forecast path of Typhoon Goni although wind speeds should drop below the 200 km/h range by the time it reaches the island on Saturday, the centre said.