I'd also suggest that people took enough warm clothing out with them in this weather. Sunday was a case in point, it started off brilliantly but got grey and chilly as the day wore on.
Someone out for the whole day who'd dressed for the morning sunshine could have been caught out as the temperatures dropped. A touch of hypothermia can cloud your judgement and slow your reactions - add to the mixture the things the other folk have suggested and you've got all the ingredients for an accident
Which is not, by the way, any sort of a dig at those who've had painful experiences over the last few days.