London amber weather warning: hose pipe ban to come into effect as heatwave returns

As the UK prepares for another very warm week, when will the heatwave arrive in London?

A heatwave will once again engulf London, with the mercury set to hit 32C.

In fact, the severity of the heat in the capital has led to the Met Office once again issuing an amber weather warning from Thursday to Sunday.

Despite stating it had no plans to introduce a temporary ban, Thames Water has now confirmed that it will press ahead with a hose pipe ban in London.

Londoners can expect a big difference in temperatures this week compared to last week - and yes, the Met Office is expecting London to meet their definition of a heatwave.

Mayor of London Sadiq Khan (Photo by Tristan Fewings/Getty Images for Pride In London)

The Mayor of London Sadiq Khan has expressed his concern amidst the extreme heat warning issued by the Met Office: “A level three heat alert has been announced today and I am urging all Londoners to stay safe and vigilant in the hot weather, especially in the wake of the devastating fires seen around London.”

“Londoners need to exercise caution and seek shade as much as possible and avoid being in the sun between 11am-3pm. You can find places to keep cool using our cool spaces map. If you are out and about in London, make sure you have a water bottle with you which you can refill at one of our 400 refill stations and 100+ water fountains.

“I am also asking Londoners to continue to look out for the most vulnerable, including the elderly, those living alone, and those with chronic or severe illnesses.”

The Mayor of London has also activated his Severe Weather Emergency Protocol to protect vulnerable rough sleepers during the heatwave.

Pesestrians walk along The Millennium Bridge away from St Paul's Cathedral in London

How hot will it get in London this week?

It’s going to get very warm in London towards the end of the week according to the Met Office, though not as warm as other parts in the south of England.

The hottest London will get is 32C on Saturday, though temperatures will start to drop a little from Sunday onwards.

As the Met Office has determined that a heatwave in London as “any consistent temperature for three days or more over the 25C threshold”, London is currently in the midst of the heatwave.

When will the heatwave arrive in London?

Though by the Met Office definition what a heatwave is means that London is currently experiencing one, those wanting to know if it’ll get hotter can expect temperatures to climb consistently over the next few days.

London hopefully will get a respite by Monday, with the Met Office forecasting chances of well needed showers in the area.

What does the rest of the week look like in London?

The Met Office have forecast that across the next five days:

  • Wednesday - sunny (28C/18C)
  • Thursday - Amber weather warning (30C/19C)
  • Friday - Amber weather warning (31C/20C)
  • Saturday - Amber weather warning (32C/21C)
  • Sunday - Amber weather warning (32C/20C)
  • Monday - Light showers changing to cloudy by nighttime (27C/18C)

What is the long-range forecast for London?

The long-range forecast from the Met Office has stated: “the start of the period will likely be fine and sunny for most. Cloud and outbreaks of light rain may be seen in the far northwest on Friday, along with possible coastal mist or fog. Winds are expected to be mostly light and temperatures above average, becoming warm in the north and hot in the south.”

“Into the weekend and through next week, mainly dry and settled weather will likely continue for most. The north is expected to see the most of any precipitation, but there is also a low risk of thunderstorms developing in the south”.

“Temperatures will likely be very warm, locally hot for much of England and Wales, especially across the southern parts, but closer to normal while still warm elsewhere.”

What is an amber weather alert?

An amber alert is issued by the Met Office when there is an increased likelihood of impacts from severe weather, which could potentially disrupt your plans. This means there is the possibility of travel delays, road and rail closures, power cuts and the potential risk to life and property.

The Met Office consider Liverpool’s amber alert warning to mean:

  • Adverse health effects are likely to be experienced by those vulnerable to extreme heat
  • The wider population are likely to experience some adverse health effects including sunburn or heat exhaustion (dehydration, nausea, fatigue) and other heat related illnesses
  • Some changes in working practices and daily routines likely to be required
  • An increased chance that some heat-sensitive systems and equipment may fail.
  • More people are likely to visit coastal areas, lakes, rivers and other beauty spots leading to an increased risk of water safety and fire-related incidents.
  • Some delays to road, rail and air travel are possible, with potential for welfare issues for those who experience prolonged delays

Will London now receive a hose pipe ban?

Visitors to Greenwich Park walk on the the dry brown grass in front of the National Maritime Museum in east London on July 23, 2018.

Thames Water, have now announced that a temporary hose pipe ban will come into effect in the “coming weeks.”

The company's decision to announce a hosepipe ban comes after it emerged that environment chiefs could declare an official drought in parts of the England as early as this week.

Thames Water issued a statement, saying that "given the long term forecast of dry weather and another forecast of very hot temperatures coming this week we are planning to announce a temporary use ban in the coming weeks."

Thames Water have advised residents in London to practice water-saving, including:

  • Washing up using a bowl
  • Only fill the kettle with the amount of water needed
  • Using mulch for gardens rather than sprinklers
  • Spending less than a minute having a shower
  • Turning off the tap when brushing your teeth
  • If you must water your garden, use a watering can and water your plants early morning or late evening.

What is a heatwave?

A heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity.

A UK heatwave threshold is met when a location records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold.

The threshold varies by UK county.

Heatwaves are most common in summer when high pressure develops across an area. High pressure systems are slow moving and can persist over an area for a prolonged period of time, such as days or weeks.

They can occur in the UK due to the location of the jet stream, which is usually to the north of the UK in the summer. This can allow high pressure to develop over the UK resulting in persistent dry and settled weather.