Cold weather in the Pacific Northwest and Rocky Mountains pushed Western energy prices higher throughout the week.

Temperatures dropped into the 20s and 30s in the Portland area Oct. 29 and 30, while some portions of Washington fell into the 20s—even the teens—Oct. 30.

This was mild compared with Peter Sinks, Utah, which plummeted to minus 45.5 degrees Fahrenheit that same day, setting a record for October in the continental United States. Utah saw numerous all-time daily records for October broken. Some records had stood since the 1800s, according to the National Weather Service.

Northwest peak power prices responded, with Mid-Columbia prices jumping 74 percent or $21.90 in trading to $51.60/MWh, while California-Oregon Border values gained 71 percent or $20.50 to reach $49.50/MWh. South of Path 15 was the exception, dropping $9.60 to $37.75/MWh.

By Oct. 31, peak power prices ranged from $37.75/MWh at SP15 to $51.60/MWh at Mid-C.

Similarly, off-peak Western power prices gained between $5.55 and as much as $19.20 in trading. Mid-C nighttime power values increased the most, up 76 percent or $19.20 to $44.35/MWh. When trading concluded Oct. 31, prices ranged from $32.25/MWh at Palo Verde to $44.35/MWh at Mid-C.

California Independent System Operator demand reached 32,753 MW Oct. 25, which should be the week's high. Total renewables on the CAISO grid reached 12,526 MW Oct. 29, providing roughly 46 percent of demand. Thermal generation sources fulfilled 18,017 MW, or roughly 55 percent, of demand Oct. 25.

Western natural gas prices generally gained between 5 cents and as much as $1.44 in Oct. 24 to Oct. 31 trading. El Paso-Permian Basin natural gas jumped $1.44 to $1.74/MMBtu. 

Notably, Sumas natural gas reached $4.11/MMBtu Oct. 29 before trending down to $3.40/MMBtu, which was a 63-cent increase. Opal natural gas gained 64 cents to $2.87/MMBtu.

The U.S. Energy Information Administration stated in its weekly report that "Because much of the natural gas delivered into California flows through the Opal and Sumas hubs, California natural gas spot prices also rose." Indeed, by Oct. 31, SoCal CityGate gas added 51 cents to end at $3.74/MMBtu and SoCal Border gained 22 cents to reach $2.58/MMBtu.

Henry Hub gained 58 cents in trading to end at $2.69/MMBtu.

Working natural gas in storage was 3,695 Bcf as of Oct. 25, according to the EIA. This is a net increase of 89 Bcf compared with the previous week, and is 559 Bcf more than at this time last year.

The average rate of net additions to storage to date is 27 percent greater than the five-year average recorded in the refill season, which spans April to October.