Last month was hottest June on record worldwide, more heatwaves on the way - NASA

NASA says last month was the hottest June worldwide since records began, and now July is gearing up to be one of the warmest with a heatwave gripping parts of the United States.

In June in Greenland, sled dogs would normally be running on ice. The melt season runs from June to August but on June 13, 40 percent of the island's ice sheet experienced melting. 

Last month a severe heatwave smashed records across western Europe, with temperatures reaching 46C in one region.

That's hotter than the record set in 2003 when a heatwave across Europe led to more than 70,000 deaths.

NASA says globally last month was the hottest June on record, almost one degree above average and beating the 2016 record. 

Back home, the National Institute of Water and Atmospheric Research (NIWA) says an unusually dry June and less rain than normal has seen a poor start to the ski season for some - and July is heating up.

"At the moment we're tracking around two degrees above average across the country," says NIWA weather forecaster, Nava Fadaeff.

In the US, a big bubble of heat covers the mideastern states and extreme heat warnings are in place.

The last three summers in New Zealand have been some of the hottest on record.

Latest figures show 157 million more people worldwide were impacted by heatwaves in recent years.

"[From] what we've seen in New Zealand and globally with the heatwaves, we're expecting this trend to continue - more hot days, more extreme days temperatures above 30C, more heat days - how many more depends on what humans do to respond to this," says Fadaeff.

The Red Cross says heatwaves are the deadliest natural hazard facing humanity, releasing new guidelines for cities to reduce the dangers of heatwaves.

These include establishing systems that warn people about predicted high temperatures, making sure hospitals are prepared for an influx of patients, creating cooling centres, creating more green spaces and introducing car-free zones.