With the wind blowing and the temperatures plummeting this January, it's well and truly woolly hat weather.
But a handful of stars, including singer Annie Lennox, Silent Witness star Emilia Fox and TV personality Phil Spencer are going without their hats this winter to help raise money for the UK's homeless who face going without a warm bed and sleeping in the cold every night.
Instead, on Friday January 29, their hats will be sold off as part of a Celebrity Hat Auction, hosted by homeless charity St Mungo's to mark Woolly Hat Day 2016.
Also included in the auction is a hat signed by cyclist Sir Bradley Wiggins, Brian May's black cap which he wore on his debut solo tour in 1993 and Michael Palin's signed navy cap with ‘Michael Palin in the Himalayas’ stitched into the front.
Now in its sixth year, Woolly Hat Day sees thousands of people wearing beaded beanies, signed baseball caps and beautiful berets to help St Mungo's raise money to support homeless men and women across the country. This year St Mungo's is aiming to raise £60,000 during Woolly Hat Day, which would make a life-changing difference to both homeless people and people who are in danger of becoming homeless.
And there are plenty of ways you can get involved and help St Mungo's achieve their target. The best way is to bid in the online celebrity hat auction for a famous piece of headgear (from January 22 Jan-31) by visiting www.woollyhatday.org.
Get your own woolly hat on and celebrate with a donation to St Mungo's. Again, head to www.woollyhatday.org. to donate or else text WOOL16 £3 to 70070. Then tell all your friends by sharing a picture of you on social media. You can join in the action on Facebook at www.facebook.co.uk/StMungosUK and on Twitter @stmungos or by following the hashtag #WHD16.