Heat alert trial - summer 2021

Heat alert trial aims to help reduce health impacts from hot weather

What does the project involve?

The heat alerts pilot is a first in New Zealand, and has been developed and produced by MetService, the Climate Change Research Institute (CCRI) at Te Herenga Waka—Victoria University of Wellington, and the Institute of Environmental Science and Research (ESR). The pilot is a first step towards supporting communities at greatest risk from health impacts related to climate change.

As part of the pilot, MetService will monitor heat alerts for 22 locations across Aotearoa. When a significant heat event is forecast for one of the locations, a heat alert banner for the affected area will appear on the respective forecast page on metservice.com. 

Strong evidence shows that extreme heat and heatwaves have negative impacts on health. Extreme heat can cause illness and death, but effective planning and actions can reduce its effects on health. Because effects of heat are associated with relative rather than absolute temperatures, even in New Zealand’s temperate climate people can experience negative health effects with modest increases in seasonal temperature. Everyone is vulnerable to extreme heat. However, babies and infants, older people, those with pre-existing medical conditions or on certain medications are more at risk.

Tips for managing in hot weather events  

If you or others feel unwell

If you feel dizzy, weak or have an intense thirst or headache you may be dehydrated.

Drink water and rest in a cool place. Seek help if symptoms persist. 

If you are experiencing painful muscle cramps, your body may need electrolytes as well as fluid.

Drinking oral rehydration solutions or zero sugar sports drinks may help.
Seek medical advice if heat cramps last for more than one hour. 

Keep medicines below 25 degrees C or in the refrigerator (read the storage instructions on the packaging).

 

Keeping yourself and others safe in hot weather:

Drink plenty of water - try to drink two litres per day

Stay out of the sun

Have plenty of cold drinks

If you need to be in the heat, stay in the shade where possible

Avoid drinking alcohol, caffeine, and hot drinks

Use sunscreen

Eat nourishing food with a high water content (such as salads and fruit)

Wear a hat

Dress yourself and children in light clothing, cool cottons and natural fabrics are best

Avoid extreme physical exertion

People and pets should not be left in stationary vehicles

Take a cool shower of bath

Check in on others, especially those at most risk, children, elderly or those with health issues

Spray or sprinkle water over skin or clothing, a damp cloth on the back of the neck can help

heat awareness3 pets and animals

 

Tips for keeping your home cool

Open windows in the evening and overnight, once temperatures have cooled

 Turn off non-essential lights and electrical equipment – they generate heat.

 Home insulation will help keep your home cooler in summer

 Move into a cooler room if possible, especially for sleeping

 Keep light-coloured curtains or blinds closed on windows facing the sun during the day.

Dark coloured curtains or blinds are best left open as they absorb the heat

 Use electric fans to keep cool 

Use the cool cycle on a heat pump. Clean heat pumps – vacuum the filters regularly.

 

 

What are the thresholds that define a significant heat event?

To define temperature thresholds for the 22 locations selected for the trial, hourly observation data is used from MetService weather station locations nationwide to calculate the daily maximum” feels like” temperature. The “feels like” temperature is calculated using temperature, humidity and wind. MetService has over 25 years of hourly data for each location in the trial. 

When two consecutive days are set to meet or exceed the respective threshold for the weather station at that location, a heat alert will be issued.  

Location

Two-day threshold (degrees)

Location

Two-day threshold (degrees)

Gisborne

31

Whakatane

28

Hamilton

30

Rotorua

28

Napier

29

Taupo

28

Timaru

29

Tauranga

28

Ashburton

29

Blenheim

28

Lower Hutt

29

New Plymouth

27

Whangarei

29

Queenstown

26

Dunedin

28

Nelson

26

Auckland

28

Oamaru

26

Christchurch

28

Invercargill

26

Paraparaumu

28

Hokitika

24

We've taken three factors identified by the Ministry of Health that contribute to heatwaves, to define a heat alert event

Day-time temperatures - the increase in above average temperature can cause adverse impacts on health. Locations with higher average temperatures (Gisborne for example) have higher thresholds than locations with lower average temperatures. 

Humidity – High levels of humidity can make it feel hotter (perceived heat) and can negatively affect the body’s cooling mechanisms. Humidity has a marked effect for some locations , such as Auckland.

Duration – Heat alerts are based on a threshold being reached for at least two consecutive days. Extended periods of hot and/or humid weather increase the risk to and impact on health.

What happens when a threshold is met?

As part of the trial for the 2021/22 summer, a heat alert banner will be generated on metservice.com, on the respective forecast page of the location. MetService may also use social media to generate awareness of the heat event. In the case of heat alerts within the Canterbury region, MetService is providing data ditrectly to the Canterbury District health Board 

When will the trial run for?

From December 2021 through to March 2022.