The UK is bracing for the fifth heatwave of the season in already dry conditions that have seen firefighters stretched to curb a huge blaze in New Forest.

People across the UK enjoyed their last cool night for a few days as a hot spell is about to land on the already parched Britain, with London and most parts of England enduring drought conditions.

The warm weather front prompted the UK health watchdog, the UKHSA, to issue heat health alerts covering all of England as temperatures begin to climb from Tuesday.

The heat alerts, most of them amber, are in place across England from 9am today until Friday evening.

Mercury is expected hit 29°C in Cardiff today, 28°C in Manchester and 25°C in London before the temperatures soar.

Officials have urged people to take simple steps to stay safe, such as drinking plenty of water, checking on vulnerable friends and family, and avoiding the sun at the hottest part of the day.

Amber heat health alerts have been issued for most of England including the Midlands, South East, North West and South West, while a yellow alert will be in force for the North East.

Scenes of dry grass resembling a savannah have become a common sight as more than two-thirds of England was declared under drought after the record-dry July.

The Environment Agency said 71.3% of England is experiencing ‘flash drought’ – a phenomenon that develops very quickly because of a combination of very low rainfall and high temperatures.

The East Midlands, Lincolnshire and Northamptonshire, Kent and East Sussex, and Solent and the South Downs have become the latest areas to move into drought, the agency said.

In New Forest, crews have tackled a fire since Sunday after a van spread to the surrounding heathland, engulfing more than 140 football pitches of the precious landscape.

Drivers fled their vehicles after the flames spread suddenly through the dry verges and into the wild near Ringwood.

Hampshire and Isle of Wight Fire and Rescue Service said this morning: ‘Crews have worked tirelessly throughout the night, a change in wind direction provided a challenge to the firefighting operations but thanks to the efforts of firefighters we are managing to contain the fire. We have been using a mix of fire engines and off-road vehicles to damp down and cool the edges of the area involved in the fire to prevent spread and escalation.

‘The police drone is being used to enable us to prioritise hot spot areas and manage flare ups.’

Meanwhile, crews in South Wales have been tackling multiple wildfires, including at Cwmavon Woods in Blaenavon, Wattsville in Sirhowy Valley and Abernant in Aberdare.

The Fire Brigades Union said on Monday evening: ‘In the last 48 hours, we’ve seen major wildfires in Nottinghamshire, Hampshire, South Wales, and Suffolk. This is not bad luck. This is climate change, and firefighters are on the frontline.’

MORE: London’s parks are yellow and dusty — doctors say you need this ‘irksome’ item to stay safe

MORE: Why are there so many flies around?

MORE: Londoners dive out of the way of ‘dust devil’ barreling through park