The Snowdon Sunset Trek should raise more than £25,000 for St Barnabas House hospice.
The team of 41 trekkers timed the mountain climb to reach the summit for sunset.
They battled rain and strong gusts of wind along the Llanberis Path but still the majority made the top within three and a half hours.
They then descended in darkness, using head torches to light the way, and crossed the finish line in less than seven hours.
Lucy Brady, events fundraiser, said: “I am extremely proud of all of our trekkers. To reach the summit of Mount Snowdon in those conditions was an incredible achievement and a challenge for even experienced walkers.
“Capel Curig, which is a local village based approximately eight miles from Snowdon, recorded 34mm on rainfall on the Saturday. The average monthly rainfall in Worthing for the whole of September is only 51mm, which shows what we had to contend with.
“I would like to say a massive thank you to all of the walkers who have contributed to raising an incredible amount of money for the hospice.
“Once all the sponsorship is received, we are expecting to raise over £25,000, which is more than enough to pay for all the care provided by St Barnabas House, both at the hospice and in the local community, for the whole time we were doing the challenge.”
Steve Hobbs, 57, from Littlehampton raised more than £3,400 in memory of his father, Frank Hobbs.
Frank had metastatic prostate cancer and was admitted to the in-patient unit for two weeks of respite care in October 2017. He was readmitted on Boxing Day last year and was cared for at the hospice until he passed away on January 29.
Steve, who owns Ford-based refurbishment specialist Warnes Projects, said: “Dad was really quite frightened about it but within a couple of days of being there for respite care he said ‘I don’t particularly want to come back but if I’ve got to go anywhere I want to go to St B’s’.
“He was very at peace with it all. We had time to chat to him and have family time, whereas while he was at home we were all having to look after him. Mum could be mum. We had all the kids and the grandkids and the great-grandkids come over to the family room and had a tea party with him one day.
“Mum stayed over for a few nights. They made a bed up for her and they had a New Year’s Eve party there, Mum and Dad, which was nice.”
Steve said he chose the Snowdon Sunset Trek because it was a realistic challenge he could do to raise money for the hospice.
“It’s something I thought would be difficult but not too emotional, although it was when we got to the top,” he adde.
“It was hard, I can’t believe how I feel now, but it’s one I could do that people can identify with.
“I could walk up Snowdon 20 times and it wouldn’t be enough money. You can’t put a value on what the hospice has done. You’d never be able to pay it back. I thought I’d do this because it’s something I can do to try to raise some money. I’m really pleased with how much I’ve raised and long may it continue.”
Tanya Clubb, 37, from Worthing raises £678 in memory of her sister Sammie, who was cared for by the hospice in 2016.
She said: “We lost her two years ago at the age of 28. She had cervical cancer and was only in the hospice for three days. They showed so much love, care and dignity in those three days.
“St Barnabas are truly amazing in all they do and I will try my hardest to raise money for them where I can.”
Tanya completed the trek with her step-dad, Richard Pattinson, and childhood friend Amanda Digweed.
She added: “These two were my rock throughout the trek and I couldn’t have done it without them.”
The next trekking challenge for St Barnabas House will see 42 walkers travel to India on October 18 to take on the Himalayas.