It's not unknown for the A9 to be closed for days, but it is rare. In such bad conditiions it is more likely the A9 will close shortly after dusk and be re-opened as soon as possible after first light, local radio or the Matrix signs should warn of estimated closing time. Under such conditions traffic may be organized in convoys with a blower and plough leading, and a plough following up the rear, when drifting is heavy and visbility very poor, so expect substantial delays. However be warned, BEAR Scotland seem to be much quicker to shut the gates than the Highland Council were.
Until BEAR took over it was unheard of for the A9 to be shut between Inverness and Strathspey, it just didnt get closed, it has been closed on numerous occasions since Bear took over.
In 2001 the Highland Council would throw whatever it took to keep it open. Numerous nights heading up to the Slochd with a 8inchs to a foot of lying snow, perodic white outs and visibility 10feet at best, but the constant ploughing kept the drift depths down to passable levels, BEAR just give up and save their fuel bills!
To underline the point, made it to Aberdeen via the A939 one day the A96 was closed last winter, 'nuff said!