With yesterday's temperatures reaching close to the 30s, health officials want to remind people that extreme heat can be deadly.

Dr Alistair Humphrey says NIWA's prediction of an El Nino summer seem to be on the mark, with hot windy weather already basking regions.

Scorcher temperatures are being recorded all over New Zealand. File photo.

'Yesterday was exceptionally hot and while it's great to enjoy these summer days, if we get several consecutive days at extreme temperatures, it can pose a number of health risks or can even be deadly for some people and animals.”

Alistair says people need to protect themselves from the sun and slip, slop, slap and wrap, drink plenty of water and stay out of direct heat wherever possible.

'Also make sure you check on any family, friends and neighbours who spend much of their time alone.

'Make sure you're pets have plenty of shade and fresh cool water available at all times and never leave pets or children alone in closed vehicles.”

He says to phone your usual General Practice Team if you, or someone you know, starts to show any signs of a heat related illness.

The three key stages indicating the onset of heat illness are heat cramps, heat exhaustion and heat stroke.

Heat Cramps occur when a person sweats profusely and drinks lots of water but does not adequately replace electrolytes lost due to perspiration.

'Drinking large quantities of water to quench thirst can dilute the body's fluids as the body continues to lose vital mineral salts through perspiration. When the body's salt levels fall low enough, painful muscle cramps may occur.”

Alistair says heat exhaustion starts with symptoms similar to heat cramps, with additional indications such as heavy sweating, weakness, dizziness, skin that feels cold, pale and clammy, possible fainting and vomiting.

Heat stroke occurs when the body fails to regulate its core temperature. As the individual's body temperature escalates above 40.5C, victims become confused, delirious, and often unconscious.

'For anyone experiencing any of these symptoms it's important to seek medical advice or in an emergency phone 111.”