Much of southern and central Europe is suffering under extreme heat, with some countries like Greece seeing temperatures of 40 degrees Celsius or more.

Here's what you need to know about this summer's heatwaves and exactly how dangerous they can be...

Where are the heatwaves and what temperatures have been reached?

The center of this year's European heatwaves have unsurprisingly been in Italy, Spain and Greece, countries which have already seen high temperatures for several days.

As of Sunday, temperatures hit maximums of 37C in Italy, 39C in Spain, 40C in Cyprus and 45C in Greece.

Italy's health ministry sent out a red alert for 16 cities including Rome, Bologna and Florence for the weekend, while Spain recorded its highest-ever land temperatures at 60C on Saturday.

The high temperatures have also spread into parts of central Europe, with Polish authorities warning older adults to stay indoors as temperatures reached 35C.

Germany saw its hottest day of the year earlier in the week, with temperatures peaking at 37.2C in the regions of Bavaria and Baden-Wuerttemberg.

The country's weather service also issued heat warnings for nearly half the country on Saturday, including Berlin and Munich.

Meanwhile in Czechia, the national meteorological office issued a health warning as it also recorded its hottest day of the year, with the mercury above 38C in several places, figures which are exceptionally high for the country.

However, Europe isn't the only continent to feel the heat as Asia and Northern America also saw extreme weather conditions. 

Japan has warned of life-threatening temperatures, with the capital of Tokyo and other places recording nearly 40C, while a powerful heatwave is currently stretching from the U.S. state of California to Texas. 

Temperatures in Arizona's state capital Phoenix have been over 43C for 16 straight days, topping 47C on Saturday, while figures for California's Death Valley - one of the hottest places on Earth - were expected to hit peaks of 54C.

How hot could it get?

Potentially record-breaking temperatures are expected in Europe next week as another heatwave approaches.

Italian media reported temperatures could jump to a possible 48C on the island of Sardinia.

That's just short of the European record high of 48.8C, which was recorded in Sicily in August 2021.

Italy's meteorological center warned people to prepare for "the most intense heatwave of the summer and also one of the most intense of all time."

The thermometer could go above 40C in Rome by Monday and even 43C on Tuesday, breaking the capital's record of 40.5C set in August 2007.

"We need to prepare for a severe heat storm that, day after day, will blanket the whole country," Italian weather news service Meteo.it warned on Sunday. "In some places ancient heat records will be broken."

Temperatures are expected to peak between 19 and 23 July in Italy, but also in Greece, Turkey and the Balkans, with meteorologists predicting that several local heat records will be broken.

Spain's heatwave is set to intensify from Monday, with temperatures reaching 44C in the Guadalquivir valley near Seville in the south of the country, according to forecasts.

Why is it happening?

The current European heatwave is likely being driven by a combination of climate change, the El Nino weather phenomenon and a stationary high-pressure system also known as an anticyclone.

"Europe is not particularly affected by El Nino events directly... therefore it is likely the high-pressure system and climate change that are the main contributors to this heatwave event," said Melissa Lazenby, a lecturer in climate change at the University of Sussex.

But there's also the extreme heat seen in North West Africa last week which has been moving northwards over Europe. 

Julienne Stroeve, a professor of Polar Observation & Modelling at University College London, explains there is currently a heat dome stretching from north Africa through to southern Europe.

"This appears to be stuck in place at the moment and thus the persistence of the heat wave," she said. "This blocking pattern is what is keeping the warm stuck in place for now."

Then there are the unusually high sea surface temperatures across the region, with many parts of the Mediterranean seeing surface highs of 25 to 28C. 

"This will exacerbate the effects of the heat over surrounding land areas, as even in coastal regions overnight temperatures are unlikely to drop much below the mid-20s Celsius," said Rebekah Sherwin, an expert from the UK's Met Office. 

But more generally, this summer's European heatwave is representative of trends over the last few years, with the continent warming much faster than others in recent decades.

How dangerous is it?

As the mercury climbs up the thermostat, European authorities across the continent are issuing temperature warnings, with some taking more drastic action to protect people from the heat.

The Acropolis, Greece's most popular tourist attraction, has been closed during the hottest hours of the day to protect visitors.

Italy's health minister Orazio Schillaci also urged people - particularly those in Rome - to take care.

"Going to the Colosseum when it is 43C is not advisable, especially for an elderly person," he told Il Messaggero newspaper on Sunday, adding that people should stay indoors during the hottest part of the day, between 11 a.m. and 6 p.m.

The extreme heat has also made wildfires far more likely. On the Spanish island of La Palma, one blaze ripped through 5,000 hectares this weekend forcing the evacuation of 4,000 people.

On the Spanish mainland, forecasters also warned of a greater risk of forest fires, while fires have broken out in Croatia, burning houses and cars in at least one village on the Dalmatian coast. 

There are also concerns in Greece that wildfires could cause particular damage, especially in areas with high winds. 

Authorities have banned access to nature reserves and forests to reduce the risk of wildfires, while Greek municipalities were also set to open air-conditioned areas in public buildings for people to shelter from the heat.

What can you do to stay safe?

To keep safe, authorities have been warning people - particularly the elderly and those with underlying conditions - to watch out for signs of heatstroke. 

That includes hot, dry skin or excessive sweating, and confusion. More extreme symptoms can include loss of consciousness, seizures or fits and a very high body temperature.

The best way to protect yourself is to keep out of the sun, especially around midday, to stay hydrated and if you can, remain indoors with the curtains drawn.

The U.S.'s Centers for Disease Control and Prevention also recommends people wear lightweight and loose-fitting clothing, drink plenty of fluids and don't drink too much alcohol. 

Using sunscreen with a high SPF and UVA rating is also a must, while it's important not to leave anyone, especially babies, young children and animals, in a locked vehicle. 

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