Severe Thunderstorm Warning: What It Means and What to Do
A Severe Thunderstorm Warning in Australia means the Bureau of Meteorology (BOM) expects or has detected a thunderstorm capable of producing large hail (2 cm or more), damaging wind gusts of 90 km/h or more, heavy rainfall that may cause flash flooding, or a tornado. If a warning is issued for your area, move indoors and away from windows, secure loose outdoor items, avoid floodwater and fallen power lines, and keep checking BOM and local emergency service updates.
Here’s what triggers a BOM Severe Thunderstorm Warning, how to get the house and car ready, and what to do while it’s overhead. Then there’s getting through the blackout on battery power you can run indoors, and what’s worth checking once it’s passed over.
What Does a Severe Thunderstorm Warning Mean?
An ordinary storm is the sort you watch from the kitchen window with a cuppa. A severe thunderstorm’s a different animal, one capable of structural destruction: the updraught holds hail up there until it’s too heavy, then drops the lot on a suburb.
What Conditions Trigger a Severe Thunderstorm Warning?
The Bureau doesn’t hand these out for a bit of thunder. According to the Bureau of Meteorology (BOM), a storm is classified as severe if it is producing, or expected to produce, at least one of four hazards:
Large hail: Hailstones measuring 2 cm across - roughly an Australian $2 coin - or larger.
Damaging wind gusts: Peak speeds of 90 km/h or more, where gum limbs come down and roof tiles lift.
Heavy rainfall leading to flash flooding: Downpours heavy enough to swamp the stormwater system and turn a street into a creek.
Tornadoes: Rotating columns of air that can flatten houses in seconds.
Hazard | BOM Severe Threshold | Main Risk |
Large Hail | ≥2 cm diameter | Smashed windscreens, cracked solar panels, dented car and ute roofs |
Damaging Winds | ≥90 km/h gusts | Snapped power lines, fallen gum trees, lifted roof sheeting |
Heavy Rainfall | Localised flash flood rate | Rapid street flooding, flooded garages, engine hydro-locking |
Tornado | Any confirmed or suspected funnel | Concentrated structural collapse, flying high-speed debris |
What Hazards Can a Severe Thunderstorm Bring?
Lightning’s a hazard in its own right - it starts fires in dry grass and travels through anything conductive. Fallen limbs bring down live wires, and one branch across a line can leave nearby homes in the dark. Microbursts are the other one. Sinking air hits the ground and fans out with cyclone force, and whatever wasn’t tied down - trampoline, wheelie bin or shade sail - becomes something that flies.
What Types of Severe Thunderstorm Warnings Are Issued in Australia?
The Bureau issues two kinds of warning. Which one lands on your phone depends on where the storm’s sitting and how well the radar can see it.
Regional Severe Thunderstorm Warnings cover a broader area and name the forecast districts in the firing line. They’ll tell you what to expect, whether that’s damaging winds, large hail or heavy rainfall, but they rarely put an arrival time on your suburb.
Detailed Severe Thunderstorm Warnings are issued for selected metropolitan areas once the radar can track the cell closely enough to say where it’s heading. These place the cell, show which way it’s running, and name the suburbs in its path with arrival times.
Every so often a storm gets flagged as a very dangerous thunderstorm. These may produce giant hail 5 cm or larger, destructive wind gusts of 125 km/h or more, tornadoes, or intense rain that could lead to dangerous and life-threatening flash flooding.
What Should You Do When a Severe Thunderstorm Warning Is Issued?
From the moment the alert lands, you’re racing a clock you can’t see.
Move Indoors and Stay Away From Windows
Get inside, pets and all. Skylights and windows are a house’s weak points in a hailstorm, because wind-driven hail and flying branches don’t bounce off them - they come through. Pull the curtains so any glass lands on fabric rather than the floor, and stay off corded phones and out of the shower while the cell’s overhead, since plumbing and phone lines both carry a strike into the room.
Secure Outdoor Items and Protect Your Vehicle
A sudden 100 km/h westerly gust will shift an outdoor setting across the yard without working up a sweat. Get the cantilever umbrella down, stack the chairs, and peg the trampoline down. Garage the car if you can; if you can’t, move it clear of the big eucalypts and throw doonas or blankets over the windscreen and roof. It looks ridiculous, and it saves the glass.
Avoid Floodwater, Fallen Trees and Power Lines
Don’t drive, ride or walk through floodwater, however shallow it looks. Moving water can knock people off their feet or move vehicles, and you can’t tell whether the road underneath has been damaged or washed away. Treat every downed cable as live: stay 8 metres clear, keep everyone back, and report it to your distributor.
Keep Checking Weather Warnings and Emergency Updates
Check the BOM Weather app for current warnings and radar updates. A thunderstorm tracker can help show potential storm movement, but it does not replace an official warning. For what to do about it, follow your state or territory emergency service:
NSW & ACT: NSW SES / ACT ESA
QLD: Queensland Fire Department (QFD) / Queensland SES / Disaster Management Queensland
VIC: VicEmergency
WA, SA, TAS, NT: Respective state SES and emergency alert channels
For storm or flood damage, call the SES on 132 500; if someone’s in danger, dial Triple Zero (000). Download the Emergency+ app before the season too - it’s free, and it puts your GPS coordinates on screen when you can’t name the street.
Storm Risk | What to Do |
Approaching Hail & Damaging Winds | Park vehicles under cover, bring pets inside, lock exterior doors and windows. |
Local Street & Gutter Overflow | Unplug ground-level appliances; stay inside on high ground; never drive into floodwaters. |
Downed Power Lines in the Street | Stay at least 8 metres away, keep others clear, and call your power distributor or 000. |
Roof Leak or Fallen Tree on House | Shelter in the safest internal room; call SES on 132 500 for emergency tarping. |
How Can You Prepare Your Home Before a Severe Thunderstorm?
Late spring and summer can bring an increased risk of severe thunderstorms in many parts of Australia, so it’s worth preparing the property before storm season gets underway.
Secure Your Roof, Yard and Outdoor Equipment
Start at the top. Gutters choked with gum leaves back up fast in a downpour. The water then goes under the eaves and comes out through your plasterboard ceiling, and that’s a more expensive fix than a Saturday on a ladder. Clear them and the downpipes every few months. Then look above: cut back dead branches over the roofline, check the ridge capping and cracked tiles, and give the antenna and solar brackets a shove.
Prepare an Emergency Kit
Keep it simple - one waterproof tub you can reach in the dark. A power outage survival kit checklist can help you organise supplies for a storm-related blackout. Stock it with:
A battery-powered or hand-crank AM/FM radio, the thing that still works when the mobile towers drop out
High-lumen LED torches and spare batteries
A first-aid kit, prescription medications, and copies of important papers
Several litres of bottled water and non-perishable snacks
Sturdy work gloves, waterproof ponchos, and cash, since EFTPOS goes down with the power
Charge Phones, Lights and Essential Devices
Charge phones, tablets, lanterns and power banks ahead of the storm, while it is safe to do so. A charged portable power station can also help keep compatible essentials running if the mains power fails. Disconnect mains-powered electronics before the storm arrives; avoid handling them during lightning activity.
How Can You Prepare Backup Power for a Severe Thunderstorm?
Lightning and fallen limbs take out substations regularly, and a street can be without mains power for hours, or days. A battery backup suits a suburban home better: you can run it indoors, it’s quiet, and there’s no fuel to store and no exhaust near open windows, which is more than you can say for a petrol generator.
Estimate Your Essential Power Needs
Think about what you’d miss with the power off for hours - keeping food cold, staying connected, charged phones, light after dark - and put medical equipment at the top of the list. Internet access may also depend on backup power for your NBN equipment and router, as well as whether the wider network remains operational during the outage. Knowing how to calculate kWh usage helps you estimate the energy your essential devices need over the expected outage.
Prepare Backup Power for Basic Household Devices
For a short blackout, prioritise the NBN modem and router, lights, phones, a fan and the fridge. The EcoFlow DELTA 3 Portable Power Station provides 1,024Wh of capacity, making it suitable for keeping these basic devices available for several hours. Runtime comes down to each appliance’s average consumption and startup power.
Prepare More Backup Power for Longer Outages
If an outage runs a day or more, the maths changes: the bore pump has to run, the fridge can’t coast on cold air, and in February you’ll want the air con. That takes considerably more energy. The EcoFlow DELTA Pro Ultra Whole-Home Backup Power offers expandable capacity for larger household loads and can be recharged with compatible solar panels when conditions are safe and sunlight is available. If you plan to connect it to fixed household circuits, the system must be installed with compatible equipment by a licensed electrician.
Compare Backup Power Options for Different Household Needs
Product | Capacity | AC Output | Suitable Backup Devices | Best For |
EcoFlow DELTA 3 | 1,024Wh (expandable) | 1,800W continuous | Wi-Fi router, washer, TV, electric kettle, refrigerator | Routine suburban blackouts, apartment living, and quick plug-and-play essentials |
EcoFlow DELTA Pro Ultra | 6,144Wh (expandable to 30kWh) | 6,900W continuous | Compatible fridge/freezers, air-con, pumps and microwaves; selected medical equipment, subject to power requirements and total load | Extended blackouts, large households, semi-rural properties, and whole-home backup |
Conclusion
The Bureau can tell you a storm is coming and roughly where it’s headed, but not which street the hail will pick. What you control is smaller: clear gutters before summer, the SES number, and lights that stay on when the street goes dark. The storms keep coming. The difference is what you do with those twenty minutes - getting the car under cover and a battery topped up, or watching the sky and hoping it turns.
FAQ
How Long Does a Severe Thunderstorm Usually Last?
A single-cell thunderstorm often lasts less than an hour. The longer version is a slow-moving front or multi-cell squall, where one cell clears and the next arrives right behind it, so severe conditions roll over your region for hours.
Can You Drive When There Is a Thunderstorm?
It’s best to avoid driving during a severe thunderstorm if you can. Heavy rain destroys visibility, hail can shatter the windscreen, and flash flooding’s the part that kills. If you’re caught on the road, pull over well clear of trees, power lines and low-lying water. Put your hazard lights on and stay in the car.
What's the Difference Between a Thunderstorm and a Severe Thunderstorm?
The difference comes down to the damage it can do. A standard storm gives you rain and lightning; a severe one’s carrying gusts of at least 90 km/h, hail 2 cm or bigger, flash-flooding rain or a tornado, and that earns it an official BOM warning. Same cloud, very different afternoon.
How Does Bad Weather Affect Your Solar Panels?
Heavy cloud can sharply reduce solar generation, while hail and wind-blown debris may physically damage panels. Many solar modules are tested to recognised standards for mechanical loads and hail impact, but passing those tests does not make a panel hail-proof. Damage risk depends on factors such as hail size, impact speed, angle, and the panel’s construction. After a severe hailstorm, have the system inspected if you notice cracked glass, reduced output, or other signs of damage.
How Long After Thunder Is It Safe?
Wait at least 30 minutes after the last rumble of thunder before going back outside. Lightning can strike well away from the main rain area, so the danger may continue even after the storm appears to have passed.