June Ends with Exceptional Heat

“Fewer than 40 per cent of homes have air conditioning on the coast, people are having to go to libraries and shopping malls to find a couple of hours of air conditioning. I have been sleeping in a tent to get some respite from the heat,” said Mr Castellan.

The intense heat – especially when combined with lightning – leads to an increased risk of wildfires.

United States
Seattle set a new all-time record at 104°F (40°C) on Sunday and broke that on Monday with 107°F (41.7°C) Portland broke the record twice - 108°F (42°C) on Saturday 112°F (44.4°C) on Sunday, according to the US National Weather Service. Many other station records tumbled on Monday.

The heat is being caused by a combination of a significant atmospheric blocking pattern which has led to a heat dome, with low pressure either side, and which is not being moved along by the jet stream.

This heat wave comes on the heels of another historic heat wave less than two weeks ago that baked the U.S. Desert Southwest and California with hundreds of record highs. 

Northern Hemisphere Heat
Other parts of the northern hemisphere are already experiencing exceptional early hot summer conditions extending from the north Africa, Arabian Peninsula, eastern Europe, Iran and the north-western Indian continent. Maximum daily temperatures exceeded 45°C in several locations and reaching 50’s in the Sahara.

Western Russia and areas around the Caspian Sea have also seen unusually high temperatures due to the continued presence of a large area of high pressure. In parts of the region including Moscow temperatures are expected to reach the mid-30s°C by day, remaining above 20°C by night. Areas nearer the Caspian Sea are expected to experience temperatures reaching the mid 40s°C and remaining above 25°C at night. It is likely that some all-time temperature records will be set during this heatwave.

Climate Change
These early summer hot weather conditions are taking place in human-induced climate change background, with global temperatures are already 1.2°C higher than the pre-industrial levels.

“Heatwaves are becoming more frequent and intense as greenhouse gas concentrations lead to a rise in global temperatures. We are also noticing, they are starting earlier and ending later and are taking an increasing toll on human health,” said Omar Baddour, Head of WMO’s Climate Monitoring and Policy Division.

Nikos Christidis is a climate scientist with the UK’s Met Office. He said: “Without human-induced climate change, it would have been almost impossible to hit such record-breaking mean June temperatures in the Western United States as the chances of natural occurrence is once every tens of thousands of  years. In the present-day climate getting an extremely hot June is common and is likely to occur twice in three decades. However, an analysis from many computer models suggests that by the end of the century these extreme temperatures are more likely than not. Human influence is estimated to have increased the likelihood of a new record several thousand times,” he said.

The Intergovernmental Panel on Climate Change Special Report on Global Warming of 1.5°C contained information on climate change and human welfare. 

Climate-related risks to health, livelihoods, food security, water supply, human security, and economic growth are projected to increase with global warming of 1.5 °C and increase further with 2 °C. Limiting warming to 1.5 °C rather than 2 °C could result in 420 million fewer people being exposed to severe heatwaves, it said.

In 2018, vulnerable people over the age of 65 experienced a record 220 million more heatwave exposures, than the average for the baseline of 1986–2005, according to WMO’s report on the State of the Global Climate in 2019.