The heatwave is set to peak Thursday and Friday. (Representational)

A ferocious heat wave has overtaken parts of Europe. It has already set a number of records, and there are several days of extreme heat to go.

As the heat wave escalates towards its peak late this week, temperatures have already neared or surpassed 100 degrees (37.8 Celsius) in parts of France, Germany, Poland and Spain. Even Switzerland has seen locations rise toward the mid-90s.

While records will continue to fall in the days ahead, a number of historic marks have already been set as the heat wave cranks up.

France's meteorological agency, Meteo France, tweeted that the country posted its hottest June day on record Wednesday, with an average high temperature of 94.8 degrees. (34.9 Celsius).

In Germany, a weather station in Berlin soared to 101.5 (38.6 Celsius) Wednesday afternoon becoming the hottest temperature recorded in the country during June.

Poland set its June temperature record, with a high of 100.8 degrees (38.2 Celsius) in Radzyń in the eastern part of the country. The Czech Republic also appears to have set a June record with a temperature of 102 degrees (38.9 Celsius) in Doksany to the northwest of Prague.

Its not just day time temperatures which have been exceptionally warm. Temperatures at night have also been record-setting, presenting a dangerous situation for those without access to air-conditioning and vulnerable groups such as older adults and the very young.

The low temperature in Nice, France was just 78.8 degrees Wednesday, the warmest ever recorded in June.

Those toasty lows act as a big launching point for daytime highs.

On Thursday, France could challenge its highest temperature recorded in June or any month. A record portion of the country is under alerts for heat. The highest modern temperature in June in France is 106.7 (41.5 Celsius). Parts of southern France are projected to reach 109.4 degrees (43 Celsius) Thursday or Friday, near the country's national temperature record (for any month) of 111.4 degrees (44.1 Celsius).

Several other countries could challenge longstanding heat records in the days ahead.

From Spain to Poland, temperatures are forecast to be at least 20 to 30 degrees (11 to 17 degrees Celsius) above normal. Actual temperatures should surge to at least 95 to 105 degrees (35 to 40 degrees Celsius) over a sprawling area.

The mercury is forecast to approach 105 degrees (40.6 Celsius) in Madrid on Friday, which would be its highest temperature ever recorded.

A main cause for the massive early season heat wave is a pair of powerful high-pressure systems. One is near Greenland, and the other is over north-central Europe. As they become linked and flex over coming days, forming a massive heat dome, they'll also act to block a low-pressure system to their south, which would draw cooler air over Europe.

"Europe is currently under historically strong upper ridge," Mika Rantanen, a meteorologist in Finland, tweeted Wednesday. An upper ridge is the technical term for this extensive zone of high pressure or heat dome.

The upper level ridge is a double-edged sword. It suppresses cloud cover allowing the sun to bake the land surface and its circulation can draw even more heat into affected areas.

In this instance, the main heat feed is known as the "Spanish plume," sometimes also referred to as the "Sahara plume." The hot air plume, sourced from deserts in Spain and the Sahara, is surging through much of Europe. The result is excessive heat, and severe thunderstorms at times in some places.

The broader weather pattern behind this heat wave has connections to the stagnant high-pressure zone responsible for the big Greenland melt event in mid-June that has been breaking records for longevity. Such patterns may be becoming more common in a warming world.

Although this heat wave is set to peak Thursday and Friday, it will likely stay hot through the weekend in much of western and central Europe. Any notably cooler air holds off until next week, and it may primarily target eastern Europe as the general hot pattern holds in place.