WASHINGTON (BLOOMBERG) - Record heat is set to bear down on the Pacific north-west, threatening fresh strains on regional power and water supplies and dragging down air quality through next week.
Monthly and all-time high temperatures could envelop Washington, Oregon, Idaho, and Montana, with warming starting to build on Saturday (June 26) and lasting into next week, said Mr David Roth, a senior branch forecaster at the US Weather Prediction Centre.
Readings will rise in California and Nevada on Sunday. The sultry air will trap pollution, raising risks for people with respiratory problems.
Electric grids across the West are forecast to be stretched this summer as hot weather sends power demand surging and drought leaves less water in hydropower reservoirs.
While California may not be as hot, the state has already had its first threat of supply shortages, as officials struggle with growing heat, drought and wildfire risks linked to climate change.
"We are monitoring weather conditions closely," said Ms Anne Gonzales, a spokeswoman for the California Independent System Operator, which manages the electric grid.
She said a conservation alert isn't planned, though residents should "remain vigilant in case we need to ask for help."
The highs in the north-west could stress California's supplies as states often trade electricity across borders depending on regional needs.
Meanwhile, natural gas futures surged to a two-year high Thursday as the heat boosted demand for the power-plant fuel, exacerbating already tight supplies.
Excessive heat warnings stretch through Idaho and Washington to Northern California, where temperatures are forecast to hit 100 degrees Fahrenheit (38 deg C) or higher, the National Weather Service said. Heat warnings are also posted across British Columbia, Environment Canada said.
Seattle could reach 101 degrees Fahrenheit Sunday, just the third time it has soared above 100 degrees Fahrenheit, Mr Roth said.
Portland will likely set records for the month and date through the weekend, posting a high of 107 degrees Fahrenheit on Sunday, the weather service said. Portland's highest June temperature was 102 degrees Fahrenheit set on June 26, 2006.
The all-time record high in Washington was 118 degrees Fahrenheit set in August 1961, and for Oregon a 119 degrees Fahrenheit reading in August 1898.
Still, power supplies in the north-west are looking up as the heat rises.
The Columbia Generating Station, a nuclear facility in Washington State that provides enough power for about 1 million homes, is generating again after a scheduled refuelling.
And hydro facilities are at higher summer output levels after completion of a spring spill operation to help fish migrate, said Mr Kevin Wingert, spokesman for the Bonneville Power Administration.
Climate stress federal energy regulatory commission chairman Richard Glick said Wednesday it was "amazing" to see north-west forecasts for highs of over 100 degrees Fahrenheit.
"We know that climate change is with us and is going to present challenges in terms of the stress on the system, the demand on the system, and the stress on power plants and other generation sources," Mr Glick said at a conference.
The danger in the Pacific north-west is that many people don't have air conditioning, raising the risk of heat-related afflictions, the Weather Prediction Centre's Mr Roth said.
Across the US, more than 600 people die per year from extreme heat, according to the US Centres for Disease Control and Prevention.
The drought across the West will weigh on hydroelectric generation, and there probably won't be much wind, said Mr Jim Rouiller, lead meteorologist at the Energy Weather Group. Nearly 95 per cent of California is gripped by drought, according to the US Drought Monitor.
