How to Prepare Your Household for Severe Storms

Severe storms move faster than almost any other household hazard. A calm afternoon can turn into damaging wind, large hail, and dangerous lightning within the hour — often with a far shorter warning window than a heatwave or a rising flood gives you. That speed is exactly what makes preparation matter: a household that already knows where to shelter, what to bring inside, and how to judge a lightning risk comes through a severe storm with far less damage and far less danger than one caught by surprise.

"Severe" covers a group of related hazards that usually arrive together: strong, gusty winds capable of bringing down trees and power lines; hail large enough to damage roofs, vehicles, and crops; torrential rain that can cause flash flooding within minutes; and lightning, which injures and kills people every year and can strike well ahead of the visible storm. Some regions also see severe storms spin up tornadoes, though that risk varies widely by location. In many places, a warming climate is linked to heavier downpours and more intense storm cells, though local trends differ.

None of this is inevitable. Households that secure their property in advance, know the warning signs, and understand how to shelter come through severe weather far better than those who don't. This guide walks through what to do before a severe storm reaches you, how to stay safe while it's overhead, and what to check once it has passed.

Understand Your Risk

A thunderstorm is generally classed as "severe" once it produces damaging wind gusts, large hail, or rain heavy enough to cause flash flooding. Many warning systems set the bar at gusts above roughly 90 km/h or hail larger than about 2 cm across — the exact thresholds vary by country, but the intent is the same: a storm capable of real damage. Lightning, by contrast, is present in every thunderstorm and is dangerous regardless of whether the storm is officially "severe."

• Know the difference between a watch and a warning. A watch means conditions favour severe storms developing nearby — it's time to review your plan. A warning means a severe storm has been detected and is imminent or already happening — it's time to act.
• Storms can build fast. A cell can go from first clouds to severe within 30–60 minutes, so the useful warning window is often much shorter than for a heatwave or a flood.
• Lightning is the most underestimated hazard. It can strike more than 10 km ahead of the rain and the visible storm cloud, so you can be at risk before a storm looks close.
• Local geography changes the risk. Homes on exposed ground, near mature trees, or with poor drainage face a higher chance of wind, falling-branch, or flash-flood damage.
• Sign up for official severe-weather warnings for your area, and keep ReadyEssentials notifications on — the app sends a severe-weather alert with safety guidance when one is forecast for your household's location.

Prepare Before a Severe Storm

• Secure or bring in loose outdoor items. Garden furniture, trampolines, umbrellas, hanging baskets, bins, and toys can become projectiles in high wind or be wrecked by hail — store them in a shed or garage, or tie them down securely.
• Trim trees and shrubs. Remove dead or overhanging branches near your home, driveway, and power lines well before storm season arrives — this is one of the most effective ways to cut wind-related damage.
• Check your drainage. Clear gutters, downpipes, and drains of leaves and debris so heavy rain can run away from the house rather than pooling against it or backing up; see How to Prepare Your Household for Flooding if your property is prone to surface water.
• Inspect the roof and outbuildings. Loose tiles, shingles, aerials, and fence panels are common sources of wind damage — fasten or replace anything loose.
• Identify your safe room now. Choose the most interior room on the lowest floor, away from windows, so nobody has to decide under pressure once a warning is issued.
• Plan for a power outage. Downed lines and storm-damaged trees make severe storms one of the most common causes of power cuts — see How to Prepare Your Home for a Power Outage for what to stock and how to stay safe without electricity, including a charged power bank and a battery or hand-crank radio for warnings if the internet or mobile network drops.
• Keep a go bag ready. A severe storm can force a household to leave home at short notice, especially if wind or flooding makes a property unsafe — see What to Pack in a Go Bag: The Complete 72-Hour Evacuation Kit Checklist.
• Park under cover. If you have a garage, use it — parked vehicles are a common source of hail-damage claims.
• Make a check-in plan. Agree who will call or visit elderly relatives or neighbours living alone once a warning is issued, and again once the storm has passed.
• Review your home and contents insurance, and photograph valuables, before storm season begins.

During a Severe Storm: Lightning Safety

• Go indoors at the first flash or rumble. If fewer than 30 seconds pass between seeing lightning and hearing the thunder, the storm is close enough to strike you — take shelter immediately. As a rough guide, dividing the seconds between the flash and the thunder by three gives you the storm's approximate distance in kilometres.
• Stay inside for a full 30 minutes after the last thunder you hear. Many lightning injuries happen as people head back outside too soon, thinking the storm has already passed.
• Once inside, stay away from corded phones, plumbing, and wired electronics. Lightning can travel through wiring and pipework — avoid showering, bathing, or washing dishes until the storm has cleared, and unplug sensitive electronics in advance if you safely can.
• If you're caught outside with no building nearby, get into a hard-topped vehicle and close the windows. It is far safer than staying in the open, even though it isn't the metal frame itself doing the protecting.
• Never shelter under a tall or isolated tree. Trees are one of the most common lightning targets, and standing near one is genuinely dangerous.
• Avoid open ground, water, and metal structures. Fences, poles, and elevated ground all raise your risk of being struck.

During a Severe Storm: Sheltering Safely

• Stay indoors and away from windows, skylights, and glass doors. Wind-driven debris and hail can shatter glass without warning.
• Move to your safe room — the most interior room on the lowest level — if damaging wind or a tornado warning is issued for your area.
• Do not go outside to fix or check on property while the storm is still active. A lull can be temporary, and falling branches or debris are most dangerous exactly when you'd be tempted to look.
• Avoid unnecessary travel. If you're already on the road, slow down, increase your following distance, and pull well away from trees and power lines rather than stopping beneath them.
• Never drive or walk through floodwater, even if it looks shallow — moving water is far more powerful than it appears and can hide debris or a washed-out road surface; see How to Prepare Your Household for Flooding for more on this risk.
• Keep pets and children calm and away from windows — the noise and flashes can be frightening even when there's no real danger indoors.

After a Severe Storm

• Wait for the all-clear — at least 30 minutes after the last thunder — before stepping back outside.
• Check that everyone in the household, including pets, is accounted for and unhurt.
• Treat every downed power line as live. Stay well back, keep others (and pets) away, and don't touch it or anything it's resting on — including fences, water, or flood debris. Report it to your utility provider rather than moving it yourself. If someone has been in contact with a live line, see the in-app first-aid card Electric Shock for what to do while help is on the way.
• Photograph damage before you start cleaning up, for insurance purposes, and be cautious around unstable trees, roofing, and fences.
• Avoid standing water on foot or by vehicle — it can hide sharp debris, open drains, or electrical hazards.
• Check on elderly or isolated neighbours and relatives, especially if the power is out.
• Restock your kit and note what worked — and what didn't — so you're readier for the next warning.

Keeping Vulnerable People and Pets Safe

Anyone relying on electrically powered medical equipment, or with limited mobility or a sensory impairment, needs extra lead time to shelter and a backup plan for a power cut — agree this in advance rather than during a live warning. People who are outdoors often — working, camping, or out on open water or high ground — need a faster way to reach shelter and should watch the sky and forecasts closely through storm season.

Pets often sense a storm before people notice it, and many become anxious well before the first thunderclap. Bring them indoors early, keep them leashed if they're outside beforehand, and never leave them outdoors or in a vehicle during a storm. Make sure their microchip details and ID tags are current in case a startled pet bolts.