Weather: Four global climate records smashed amid warning New Zealand could hit 'higher-temperature extremes'

Four global climate records have now been broken - the hottest day on record, the hottest June on record, extreme marine heatwaves, and record-low Antarctic sea ice.

And with the weather pattern El Niño developing here, New Zealand could be in for a hotter summer than usual.

Against a red-tinged smoke-filled sky, thousands of people are fleeing the Greek island of Rhodes. They're evacuating by boat as firefighting helicopters scoop water from the ocean, the holiday hotspot now burning with wildfires.

They're feeling the heat too in the US where it's forecast July will be the hottest month ever recorded.

It's believed narrow bands of strong wind known as jet streams could be partly to blame for some extreme temperatures in the Northern Hemisphere. The air currents in the upper levels of the atmosphere are unusually stuck in place.

"In a changing climate the jet stream behaviour may also be changing, so that's an emerging area of research," said NIWA meteorologist Ben Noll.

As the mercury rises, climate records are tumbling.

"This is a little taste of things to come," Noll said.

Four global records have now been broken - the hottest day on record, and the hottest June. There's also record-low Antarctic sea ice - an area around 10 times the size of New Zealand is missing. And there are extreme marine heatwaves, ocean temperatures are up to 5C above average in some places.

"The oceans are really warm across the globe. We have El Niño. It increases the odds for certain places to see high heat extremes, then there is climate change," Noll said.

"So those three things combined are making record temperatures more likely in the Northern Hemisphere."

Meanwhile an El Niño weather pattern is also developing in the Southern Hemisphere.

"There is an increased chance to hit those higher-temperature extremes as we look ahead to summer," Noll said.

The Climate Change Minister is worried about more bushfires here.

"We've had a bit of a taste of it before with the wildfires in the Port Hills of Christchurch, and around Nelson area as well - I think there is a great chance that could happen again," James Shaw said.

But hopefully, we won't see disruption on the same scale as the people in Greece are dealing with right now.