The weather is the most important aspect of any mountain day and how you plan for it. I constantly monitor the forecasts and use many sources to try and stay one step ahead. All this being said the weather can act against the rules and you should always plan for the worst.
Its never 100% all the time
Weather forecasts are predictions and estimates not a 100% certainty. Whenever your out always plan for the worst, I’m not advocating that everybody should be carrying a 50kg daysack full of thermals and ice gear in the summer, but a certain amount of common sense is required. In the summer for example, when the forecast predicts sun all day I usually have a light waterproof in my bag”Just in case”, this ethos has got me out of many potentially tricky situations.
Which weather services to use!
Mountain Weather Information Service (MWIS) – A great service that offers forecasting for Walkers/climbers/mountaineers. They give weather forecasts for 900m and break down the fine detail into layman’s terms.
Norwegian weather service (YR.No) – This service has proved to be very reliable and provides very accurate forecasts for the main mountains of the UK. While it lacks the fine detail that you get from MWIS it certainly helps give a better understanding of what time to expect rain etc.
Met office – The Met office is a great service and offer a good mountain forecast service. Very similar to MWIS they offer relative conditions for the mountains. I do find that the MWIS forecasts are easier to read where the Met office have multiple pages to scroll through(Not good if you want a single printout of the days weather)
What should I be looking for in a forecast
- UK weather forecast: This will give you an idea on the amount of sun, rain, snow, wind etc expected across the country as a whole. This is good for predicting if a rain system is on its way out or in for the weekend.
- Wind: Wind speeds are crucial for your planning and can determine if your favourite ridge is an enjoyable day or a death trap. 30mph winds can make walking hard and knock you off balance, 40mph can impede walking and 50Mph+ can be dangerous. I always use MWIS for wind speeds as they forecast the wind speed you should expect on summits and ridges. Met office forecasts(Not the Mountain forecasts) give wind speeds at ground level, you should expect the winds to be much higher on the tops!
- Precipitation: Rain and snow will make a huge difference to the outcome of your day. Routes that you find easy in summer can become slippery and hazardous in the winter. Snow can add an extra complications and the possible use of technical winter walking gear(Axes and Crampons). If your taking out others into the hills large amounts of rain could lead your party to become wet and cold, action should be taken to combat that!
- Cloud: The cloud cover on the hills is important for navigation. Low cloud will make navigation much harder and combined with high winds can make for a gnarly day out!
- Sunshine & UV levels: While this box is rarely used in the UK (I joke) Sunshine amounts will be important for predicting things like, how much water to take, should you use sun cream, do you need hat and glasses.
- Freezing point: If your ascending a 900m mountain and the freezing point is at 500m its very possible frost/ice/snow will be present at this altitude. As stated before this is only an estimate and freezing points can be slightly higher or lower than this!