The Bureau of Meteorology has issued a severe heatwave warning for parts of the South Coast and Illawarra districts of NSW.  

Fig 1. Heatwave Severity Map for NSW over the span of Monday 18th September to Wednesday 20th September from the Bureau of Meteorology. 

This means that daytime and evening temperatures for these locations are going to be high, even by summer standards, over the following three days; from Monday 18th to Wednesday 20th. 

Australia is no stranger to heatwaves during summer, especially in the midst of a building El Niño and positive Indian Ocean Dipole event. However, this current warning has been issued approximately two weeks ahead of when the Bureau’s heatwave services officially open, and well before NSW typically see their first heatwave. 

As suggested in a previous story, the unseasonably warm temperatures expected in the next few days have ticked all the boxes which warrant for a heatwave warning to be issued for southeastern NSW. 

A heatwave is defined as three consecutive days and nights of extreme warmth for a particular location, such that it may affect the health of the occupants of this location. Heatwaves are set into three categories: 

1. Low intensity heatwaves: which are three consecutive, above-average days and nights, but are manageable by occupants of affected locations 
2. Severe heatwaves: three consecutive, above-average days and nights, which may negatively impact the most vulnerable citizens including children, the elderly and people with particular medical conditions 
3. Extreme heatwaves: three consecutive, above-average days and nights, which pose a risk to anyone in the location without the necessary means to keep themselves cool 

When calculating heatwave risk, the forecast minimum and maximum temperatures are compared to the average yearly extreme minimum and maximum temperatures for each location. Over the next few days, southeast NSW will see minimum temperatures lingering about the high teens while maximum temperatures will peak in the low-to-mid thirties for the next few days and nights. These conditions would qualify for a heatwave if it occurred in the summer months, so for September, this is very hot for a location so far south! 

Luckily the temperatures are not so bad to have an extreme heatwave warning issued, but there will still be some community members who may need assistance in the next few days. So, this is just a friendly reminder to keep hydrated, stay in the shade and to pay attention to our lovely elders, cute kids and friends in need over the next 72 hours.