Storms After a Heatwave: The 24-Hour UK Storm Preparation Checklist

After four or five weeks of dry heat, clay soil stops behaving like a sponge and starts behaving like a patio. Baked ground absorbs a fraction of the rain it would take in spring, so when the Met Office issues a rain warning off the back of an August heatwave, 30mm in an hour does not soak away - it runs sideways, straight at your gullies, airbricks and back door. That is why the first thunderstorm after a hot spell floods streets that stayed dry all winter.

The good news: warnings usually give a day of notice, and almost everything that protects a house takes minutes, not money. Work this as a countdown - water paths first, loose objects second, the house last.

Water damage in a summer storm is nearly always a blockage problem, not a rainfall problem. A gutter holding two months of dried moss will dam within minutes and pour down the wall instead. Do these jobs in daylight, the day before, while everything is bone dry and light to handle.

On cost: DIY is free if you own a ladder, and a professional clear on a two-storey terrace should be £60 to £120. Anyone quoting £250-plus, or door-knocking with emergency storm-proofing, is pricing your panic - genuine roofers are booked out after warnings, not touting. Our guide to cleaning gutters safely covers ladder setup.

• •Clear gutters and check downpipes run free - 30 to 45 minutes. Pour a bucket of water in at the far end and watch it exit the downpipe.
• •Lift the grilles on yard gullies and scoop out silt and leaves - 10 minutes. A dry summer fills them with dust and moss that sets like porridge when wet.
• •Check flat roof outlets on garages and extensions - 10 minutes. A single tennis ball of debris can pond 500 litres on a garage roof.
• •Sweep the kerbside drain clear of leaves and grit - 2 minutes. Blocked street drains are the top cause of water coming up the drive.
• •Walk the garden and note where paving falls towards the house - 5 minutes. Those are tomorrow's sandbag spots.

Summer storms arrive with gust fronts of 40 to 60mph ahead of the rain, and a trampoline mat catches wind like a spinnaker. Insurers pay out every year for trampolines through conservatory roofs, and claims are often reduced when the owner did nothing after a named warning. An hour in the garden the evening before removes almost all of that risk.

• •Trampoline: fit anchor kits (£12 to £20 for four corkscrew stakes) or flip it so the frame, not the mat, faces the wind - 15 minutes.
• •Parasols and gazebos: down, closed, laid flat or brought inside - 5 minutes. A parasol left up in a stand will not survive, and neither will whatever it lands on.
• •Garden furniture: stack chairs, strap them to the table, push the lot against a leeward wall - 10 minutes, £10 for two ratchet straps you will reuse for years.
• •Pots and hanging baskets: pots grouped against the house wall, baskets down on the ground - 10 minutes. Terracotta shatters into shrapnel at 50mph.
• •Wheelie bins: handles to the wall, tucked into an alcove or laid flat if exposed - 2 minutes.
• •Greenhouse: check clips on any reseated panes and shut the auto-vents manually - 5 minutes.
• •Fence panels: push-test each one - 2 minutes. A panel that moves at the post was leaving anyway; lift it out and lay it flat before the storm chooses where it goes.

Now the house itself. If your street has ever flooded, move the car before water appears - many flood-written-off cars were simply parked. Higher ground a few streets away and a £3 bus fare home is the cheapest insurance you will ever buy.

If water has ever come close to your threshold, deploy defences while it is dry: airbrick covers cost £15 to £30 each and fit in seconds, and our comparison of flood barriers versus sandbags explains which suits which doorway. Filled sandbags run £2 to £4 each; councils may supply them free but rarely deliver in time, so do not plan around that.

• •Charge phones and power banks to full; know where the torch is - 5 minutes.
• •Unplug non-essential electronics: TVs, computers, routers, consoles - 5 minutes. A nearby strike can push a spike through the ring main that a £2 extension lead will not stop.
• •Move irreplaceable documents and electronics off the floor of any room that has flooded before - 15 minutes.
• •Fit airbrick covers and door barriers if you are in a flood-risk spot - 10 minutes once you own them.
• •Cover the power outage checklist basics: flask filled, fridge and freezer on coldest so they coast longer if the supply drops.

Once it starts, stay inside. Do not go up a ladder or out to re-strap furniture in lightning - nothing in the garden is worth it. Never drive through flood water: 30cm of moving water floats most cars, and you cannot judge depth over a lifted drain cover.

Afterwards, photograph damage before touching anything - timestamped photos are the backbone of a home insurance claim. If water got in downstairs, work through our basement flood cleanup checklist rather than improvising with a mop. Treat post-storm quotes with the same scepticism as pre-storm ones: typical storm damage repair costs run £150 to £300 for a few slipped tiles and £300 to £600 for a fence panel and posts, so a £2,000 same-day roof quote from an unbidden van is a red flag, not a rescue.

None of this is specialist kit, and it costs around £70 in total bought calmly. Bought in a panic on the morning of a warning, half will be out of stock.

• •Gutter scoop and a bucket with a ladder hook - £8.
• •Two 5m ratchet straps plus bungees - £15.
• •Trampoline anchor kit - £12 to £20.
• •Two airbrick covers per exposed wall - £15 to £30 each, only if you are in a flood-risk spot.
• •Four empty sandbags plus a 25kg bag of sand - about £2.50 at any builders' merchant.
• •Head torch with spare batteries - £10.
• •Heavy tarpaulin and a few tile battens for emergency roof cover - £15.

Warnings sometimes land at 4pm for a 7pm storm. When you cannot do everything, do the jobs where minutes prevent four figures of damage, in this order.

• •Sweep the kerbside drain and lift silt out of your yard gully - 10 minutes, prevents most ground-floor water entry.
• •Anchor or flip the trampoline and drop the parasol - 15 minutes, prevents the classic £1,000-plus neighbour claim.
• •Move the car off a flood-prone street - 20 minutes including the walk back.
• •Unplug the electronics and charge your phone - 5 minutes.
• •Skip the gutters if they were cleared this year; do them once the weather passes.