It sounds like a contradiction.
After weeks of sunshine, dry gardens and fields that look like they’ve forgotten what rain is, the arrival of a huge downpour might seem like exactly what the ground needs.
But after a prolonged dry spell, heavy rain can actually create a surprisingly rapid risk of flooding.
And with 2026 having already delivered an exceptionally dry summer across much of England and Wales, it’s a particularly relevant issue this year. The Met Office says England and Wales were on course for their driest July in 190 years, with some areas receiving almost no rainfall during the month.
So why can very dry ground contribute to flooding?
The ground has had a hard time
During a long period of hot, dry weather, moisture is gradually removed from the soil.
High temperatures increase evaporation, while plants also take up water. Prolonged dry weather can leave soils extremely dry and, in some places, hard and compacted.
You might notice it in your own garden.
The lawn becomes brown.
The flowerbeds become hard.
You water the garden and sometimes it seems as though the water is simply sitting on the surface rather than disappearing into the ground.
That can become important when a lot of rain arrives very quickly.
Heavy rain is a different proposition
A gentle spell of rain gives water more time to soak into the ground.
A summer thunderstorm can be very different.
A large amount of rain can fall in a short period, potentially faster than the ground can absorb it.
Instead of soaking downwards, some of the water can run across the surface.
The Environment Agency specifically warns that intense rainfall following prolonged dry conditions can run rapidly over hard, dry or compacted soils and contribute to flash flooding.
And then there’s the urban problem
You don’t have to live beside a river to experience flooding.
Think about a typical town.
Roads.
Pavements.
Driveways.
Car parks.
Buildings.
All of these surfaces give rain fewer opportunities to soak into the ground.
When a very heavy downpour arrives, water can quickly collect and flow towards lower ground, drains and underpasses.
The Environment Agency says flash flooding can happen almost anywhere and can occur a long way from rivers, lakes and the sea.
The summer thunderstorm problem
Summer thunderstorms can be particularly effective at producing very heavy rainfall in a short space of time.
Warm air can hold more moisture, which can contribute to heavier summer downpours. The Met Office says that as the climate warms, heavy rainfall events are expected to become more common.
That’s why you can go from:
“It’s been weeks since we had any proper rain.”
to:
“Where did all this water come from?”
in remarkably little time.
It doesn’t mean every shower will cause flooding
It’s important not to assume that dry ground automatically means flooding whenever it rains.
Most rain won’t result in a flash flood.
The risk depends on how much rain falls, how quickly it arrives, the condition and type of the soil, the landscape, drainage systems and whether you’re in an area where water naturally collects.
A long, gentle period of rain can actually be exactly what dry ground needs.
The problem is an intense downpour that delivers a huge amount of water in a short period.
Dry weather doesn’t mean the flood risk has disappeared
There’s another slightly surprising point.
A drought and flooding aren’t necessarily opposites.
You can have very dry ground and still experience flooding from an intense storm.
In fact, the Environment Agency specifically notes that flash flooding can occur during drought conditions because dry soils can struggle to absorb intense rainfall.
And one storm doesn’t necessarily end a drought either. It can take sustained rainfall to properly replenish groundwater, rivers and reservoirs.
So what should we do?
If heavy rain is forecast after a prolonged dry spell, it’s worth paying attention to the weather warnings rather than assuming that rain simply means the drought is over.
Check official forecasts and flood warnings, particularly if you’re in an area that has flooded before.
And if flooding does occur, don’t be tempted to drive through floodwater or walk through fast-moving water. The Environment Agency warns that flash flooding can be extremely dangerous.
Britain’s weather never does things by halves
Perhaps this is another example of the strange relationship we have with the British weather.
We spend weeks asking when it’s going to rain.
Then the rain finally arrives and we start asking when it’s going to stop.
But after a long, dry summer, the first big storm isn’t necessarily just a welcome soaking.
If huge amounts of rain arrive very quickly, the hard, dry ground may struggle to cope.
So when the next spectacular summer thunderstorm rolls in, enjoy the sound of the rain from somewhere safe.
And remember that after weeks of sunshine, too much rain too quickly can create its own problems.
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