I don't know about the book 'Longbourn' but what about the coachmen waiting for passengers to travel back in cold weather in Emma, Ch. 15.
(Despite her husband's off handed assurance of snowing and strong drifting winds,) Isabella wanting to return to her children says, 'You had better order the carriage directly my love'.
Mr Knightley went out of doors to examine the weather, snow lay on the ground but a journey should not be too difficult.
'He had seen the coachmen, and they both agreed with him in there being nothing to apprehend.'
And the ball was rung and the carriages spoken for...The carriage came;'.
My impression here is the two carriages were brought around when passengers were ready to depart instead of the coach drivers and horses standing about in cold, snowy weather.
I think most gentlemen would take better care of ones' own valuble horses and servants; than to leave them waiting outside in bad weather.
But I doubt post-horses used by post houses and hired horses were so fortunate, and probably did stand around or pull coaches in inclement weather.