Over the last month the short cold spells have sprinkled snow onto the tops more frequently. It has generally been mild but with the slow cooling down that you'd expect with the days passing through October and November. Tomorrow is different. Our first winter storm will hit us from the north, bringing very cold temperatures, very strong northerly winds and lots of snow overnight into Saturday morning.

​Check out the forecasts on Met Office and Mountain Weather Information Service.

With some simple understanding of synoptic charts, it is very easy to see what is going on. The low pressure in the North Sea (L 977) is a deep energetic depression with winds spiralling around it anticlockwise. The wind direction we feel at ground level is just about straight along the black lines called isobars. If you follow these lines, you can see they wiggle down onto us from the Arctic bringing very cold air. Tomorrow night the temperature at sea level will drop to freezing.

Also, the lines are very close together. In the same way that closely packed contour lines indicate steep slopes, closely packed isobars indicate very fast moving air. Tomorrow night we expect 100mph winds on the tops from the north.

There are also occluded fronts circling the low pressure. These are the black lines with triangles and semicircles on them and they mark boundaries of air masses at different temperatures. Where you see a front you will get precipitation, and this time, since it is so cold, it will fall as snow to quite low levels.

​Tomorrow is going to be a tough day in the mountains and it is only going to get worse over night!

What does this mean for us? Well, 100mph wind will pick you up off your feet and dump you onto the ground a couple of metres away. An 80mph wind will knock you flat, a 60mph wind will make you stumble and brace against it and a 40mph will buffet you and knock you around, making walking hard work.

It will be -7C on the tops and the wind chill in addition to this will make it feel like -20C when you are exposed to it. This is seriously cold. Any exposed skin will get very cold very quickly and become damaged if it is not covered up quickly.

In the cloud and falling snow, it will be very hard to see where you are going. The ground will quickly turn white and blend into the sky so finding your way and navigating will be difficult. It will be very hard to look where you are going with the strong winds blowing snow and bits of ice into your face, unless you have goggles.

Thankfully, it looks like the worst of the winds and snow fall will be overnight, and Saturday will give us 40mph to 50mph winds dropping away a bit during the day. Snow showers will blow through but we might get some bright spells in between the showers. If you want a burly, blustery day out in the mountains to test out your new kit and to blow away the cobwebs, you will have the opportunity at the weekend!

I love burly autumn days like this, when you come home exhausted and blasted by the wind, thoroughly tested by our amazing mountains. It's my idea of a spa weekend, the thing that refreshes me and sets me up right for the week ahead.

Make sure you take all your kit though - ice axes, crampons, goggles, map compass, big gloves, more big gloves, warm hat, flask of hot drink, energy, drive, determination and the knowledge of how to look after yourself in proper winter conditions.

If you are into winter climbing, this bit of weather is good news. At the start of the winter, we need to wait until the ground cools down and freezes. Blocks need to freeze into place and turf needs to freeze solid to provide fun climbing and so that we do not damage the ground when we go climbing. Pulling turf off climbs is not cool.

Wind chill effects the ground in exactly the same way that it effects us. The wind will whip away the heat in the ground soaked up by the rocks as they baked in the sunshine all summer. We need a good few weeks of very cold temperatures and, ideally, strong winds blowing onto the crags to cool them down and freeze everything solid. If everything gets covered in snow before the ground freezes properly, the snow insulates the ground and the turf and blocks do not freeze as quickly or as well.

Wind blowing clouds onto rocks (or anything else) with a temperature below freezing will make rime grow. Rime ice is the feathery crystals of ice that grow into the wind and is what makes the crags white. Along with being frozen, this is the main requirement for mixed routes to be in suitable winter condition for us to go and climb them. So, the storm on Friday night is likely to rime up north facing crags up in the cloud and exposed to the wind. If you find something completely rocky and solid, you might well find good climbing. Take a big belay jacket though!

​Happy climbing!

​How hard is it to climb Ben Nevis in winter?
This can vary massively from day to day, and it depends on the the snow conditions underfoot and what the weather is doing at the time. The bottom half of the track is often clear of snow, with the snow line usually sitting at about 600m. From this point you should expect to be on snow all the way to the summit and back down. After a fresh dump of snow it will be very soft, and if there is a lot of it you will be doing a serious amount of wading. This is incredibly tiring and if you are with friends make sure you take turns at the front so it is not the same person doing all the trail breaking! If the snow has been through some freeze-thaw cycles (meaning the temperature has risen allowing the snow to go soggy, then the temperature drops again, freezing the soft soggy snow into snow-ice) it will be very hard and icy, so the walking will likely be easier but crampons and an ice axe will be essential.

Once on the snow you need to be comfortable using your boots to kick steps if it is just small areas of hard snow, or confident walking in crampons on relatively steep ground. Make sure your crampons are correctly fitted to your boots before you set off - the side of a mountain in 40+ mph winds and swirling snow is not the place to be adjusting them. Crampons have a habit of catching on everything - rocks, trousers, your other crampon, you name it - so make sure you practice walking in them on easier ground first. You should also have your ice axe, and know what to do with it. It can be used to provide support while you walk and also to stop a trip or slip from having dire consequences. 

A clear summit on Ben Nevis is a rare thing so expect cloud, and in the winter that means your navigation needs to be on point. In summer there is a path to follow but in winter this gets completely buried in snow, and there can be little to no difference between the ground and sky. You need to know how to take a bearing from your map, and then be able to follow it accurately on varying terrain. Once on the huge and featureless summit plateau there are cairns to aid navigation but it is common to not be able to see from one cairn to the next, or in heavy snow winters some of them get completely buried. You will still need to follow a bearing on your compass and know exactly when to make the left turn toward the summit. When you reach the summit remember that you're only half way there and you will then need to do everything in reverse, so stay switched on all the way down.

​Is there snow on Ben Nevis all year round?
Yes and no. Some of the deep gullies on the North Face can hold snow all year round but on the western side of the mountain where the mountain track is, this is not the case. The first snow usually falls in September with winter kit normally required between November and early May. The top of Ben Nevis is often hidden in cloud so you could look at the first 1000 metres and think there is no snow without realising that the top 300 metres is still very wintry. Do your research and make sure you go prepared.

Is it dangerous to climb Ben Nevis in winter?
Any mountaineering activity has it's risks but it is possible to minimise these risks and have a fantastic day in the Scottish mountains:

• Get kitted up - make sure you have all the recommended equipment so you stay warm, dry and safe. If you're not ready to invest in winter boots, crampons and an ice axe, it is possible to hire them from Scottish Mountain Hire in Fort William.
• Educate yourself - there is no point in having a map and compass if you don't know what to do with them. Do a navigation course and if you are new to winter hill walking then a Winter Skills course is highly recommended.
• Practice your skills - it might have been getting on for a year since you last had crampons on and the first time back out can feel very faffy and fumbly, so brush up on your skills and maybe make your first winter walk each season a fairly friendly one.
• Check the weather - the weather on the summit of Ben Nevis will be very different to down in Fort William. The Mountain Weather Information Service and the Met Office both produce mountain specific weather forecasts.
• Be Avalanche Aware - avalanches most commonly occur on the North Face of Ben Nevis but they can and do happen on the western side too. The Scottish Avalanche Information Service produces avalanche forecasts everyday from December to April so check the forecast and make sure you know the warning signs.
• If in any doubt, book to go with a guide. Not only will an experienced guide keep you safe and give you the best chance of reaching the summit, but you will also learn a lot along the way. 

Ten years ago this guidebook came out. It was passed on to me by Alan Kimber who edited three editions of it. Before that it was edited by Ed Grindley, Hamish MacInnes and written initially by Ian Clough in 1969. This is quite a list of people to be associated with and it is a great privilege to have this opportunity. I am very grateful indeed to Alan Kimber for passing it on to me and I hope to do as good a job as previous authors. 

The intention with the next edition is to help people decide what climb to go for given the weather and climbing conditions at the time. I remember starting out winter climbing and looking at the book with no idea about the differences in mixed climbs and ice climbs, what weather patterns were required to form any particular type of climb, and what style of climbing each route involved. It was all a bit hit and miss, with lots of misses!

I hear of people still having to go through the same process despite the huge amount of information available to everyone now. When they tell me about their climbing and the days that it did not go well, I often think that the main problem was that their choice of climb was not the best one for that day. If climbers know when rime will form and when the crags will be white and frozen for mixed climbing; and if climbers know when and why Green Gully will be formed but not Mega Route X yet, they will be able to make better decisions about what route to try and have more successful climbing trips.

What this means is building on what I started in the last book with a long section describing all the different types of climb and what each one takes to form, the influence of the weather and how that forms or strips away the conditions we are after. I am trying to let people know what type of climb each one is; that Diana is a thin face ice climb which you would not expect to see formed up until later in the winter; that Mega Route X requires snow above the climb to be present to provide water in the thaws to then freeze on the climb in the cold spells; that Blue Riband just needs a sustained cold spell to form ice and no snow is required at all. All this means that I am slowly working through every climb in the book, spending a lot of time in front of a screen, dreaming about all these wonderful climbs!

It's a nice autumn project, something to get stuck into while we wait for the winter to get going. A wet autumn can be very good for the formation of ice later on. We need water to drip out of the cracks and springs to form the ice when it gets cold. We also need the ground to cool down properly after our long hot summer, and before the snow arrives. We will need to wait and see if we get the perfect mix of weather to generate great winter climbing.

It used to be that October and November were very quiet months in the guiding calendar. It is often not great for rock climbing, being a bit too wet and cold for bare fingers. It is before the snow arrives properly apart from a few flurries and brief spells of freeze on the summits. But, there are still great things to do in the mountains here and, if you put up with some less than comfortable conditions, the landscape is in its finest autumn colours and is absolutely spectacular.

Mark came to walk up Ben Nevis and, as it turned out, he got a nice day to do it. Craig took him up from Glen Nevis and they found snow and rime on the rocks at the summit. The snow was just for decoration and certainly didn't cause any difficulties for the guys, they were well prepared and wrapped up for the cold.

Sally came up for some more rock climbing with Caspar. As I found out with John last year, being mobile and flexible is key to success. The guys travelled between Ben Nevis, Ardnamurchan and Kingussie to find reasonable rock climbing conditions, and they did find dry rock and sunshine as well. Climbing on the Ring Dyke crags at Ardmurchan is a must for any rock climber, and doing it in the autumn with stags roaring and the ground looking like it's on fire with its red and orange colours is a unique experience.

Meanwhile, Sally and I have been busy running our last Summer Mountain Leader Courses with an assessment last week, and the last one in progress this week. We've seen a huge increase in interest in these course and we have run a record number for us, nine in total between training and assessment courses. We love to work on these and help new people find their way into the outdoor industry and it is looking like we will have another busy year in 2022.

The team had a very chilly night last night, and face another one tonight before they walk out of the hills after their three day expedition. The signs are there that the temperature is dropping and winter is coming. It's time to wrap up any thought of rock climbing and summer mountain walking. It's time for winter.