Jamie will be running across Canada during part of their winter, so will encounter Arctic temperatures he has never experienced before.
We took him to Gloucerstershire University's Sport & Exercise Laboratory where they have a chamber in which the temperature can be lowered to minus 20C.
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Staying cloudy and drizzly during the morning but brighter spells will develop away from the coast.
Cloudy start for the day with a chance of some patchy drizzle in the morning.