(Bloomberg) -- Europe has been gripped by sub-zero temperatures in recent days, sending UK electricity prices to record levels and testing the limit of some countries’ power supplies.

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The UK is braced for a short-term crunch on Monday evening as freezing temperatures drive demand higher just as low wind reduces supplies. Earlier, National Grid asked two coal units being kept in a reserve to be ready to generate this evening if needed. It later canceled this request.

With London blanketed in snow, the Met Office has yellow weather warnings for snow and ice in place throughout the UK until Thursday. The cold snap is expected to last all week across northwest Europe.

The International Energy Agency warned that next year could be “an even sterner test” as Europe will have to refill gas reserves with little or no supplies from Russia.

Key Developments:

• Snow hits London flights, adding to travel misery from strikes

• Vitol is being paid £6,000 a megawatt-hour to generate in the UK’s balancing market

• EDF says nuclear restarts give confidence about supply outlook

• The EU is still fighting over a cap on gas prices

• Europe gas prices slump as LNG surge helps region battle freeze

(All times London)

UK on Track for Coldest Day in 12 Years (5 p.m.)

It’s provisionally the coldest day in the UK, the Met Office said.

UK Power Crunch Easing for Today (3:15 p.m.)

The UK’s power crunch seems to have eased slightly for this evening with more wind generation expected but prices are still very high. National Grid seems to be relying on nothing else going wrong. If there are any unplanned trips or stations that need to go offline unexpectedly, the balance could be thrown off again.