A heat wave caused by a blocking ridge of high pressure from near Greenland into western Europe has shattered June records in six nations, with France setting a new all-time record. The hot conditions are expected to ease for most of western Europe early next week. The heat wave is related to a negative phase of the North Atlantic Oscillation that has prevailed since late April. Heat waves are especially dangerous when they occur early in the summer, before people have had time to adapt to the seasonal heat. Europe's biggest heat-wave catastrophe occurred in the first two weeks of August 2003, with more than 50,000 people dying as a result.