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The weather can make or break an outdoor adventure. It determines the clothing and equipment you need. It can influence where you go and the route you take. It can stop you from leaving the house altogether.

Modern technology and techniques enable us to predict the weather with great accuracy, allowing us to make informed decisions that can be the difference between enjoying your walk and suffering through terrible conditions or staying safe and putting yourself in danger. To help ensure you’re always prepared, we put together this quick guide to interpreting weather forecasts.

Use the best forecast services

A forecast is only valuable when based on accurate information, so your sources matter. Using multiple services can help you get a better idea of the expected weather. Each one may say a slightly different thing, but aggregating several forecasts will result in a more accurate overall picture. We recommend the following services.

Met Office and Met Office Mountain Forecast

The Met Office is the UK’s national forecasting service and is regarded as one of the most accurate and insightful forecasts available. As well as the standard weather forecast, it provides a specialist mountain forecast covering many of the same areas as the MWIS forecast.

Scottish Avalanche Information Service

While not strictly a weather forecast, the Scottish Avalanche Information Service provides details of snowpack conditions in the Scottish highlands and the likelihood of avalanches occurring. It is an essential resource when hiking in avalanche-prone areas in Scotland.

Windy.com

We love Windy.com. It looks great and is a fantastic visual aid. However, it does feature a large number of complex, controllable variables and parameters and doesn’t have a particularly intuitive user interface. This makes it one for the weather/data nerds out there, as well as walkers with a bit more experience interpreting forecasts.

Know what to look for

When checking the weather forecast, build a well-rounded picture by combining information on the following factors.

Wind

Wind can have a significant impact on your walks and make mountainous terrain more dangerous. Begin by looking at:

1. Wind direction – which way is the wind blowing? How does that affect your day? Will you be walking into a headwind for a prolonged period?
2. Wind speed – how strong is the wind? Are there gust warnings in place? Anything above 35 mph will affect even fit and experienced walkers. It can be particularly dangerous if moving through exposed terrain, where there is a higher risk of falling.
3. Changes and evolution – how is the wind expected to change throughout the day? Is it constant? Or calmer in the morning and more settled in the afternoon? Changing wind conditions can affect what time you head out and how long you stay out for your walk.

Those new to walking often underestimate the impact wind can have on your outdoor experience. Rain is often considered the main threat to an enjoyable walk. In reality, wind is much more likely to stop you in your tracks or prevent you from reaching a summit.

Temperature

It can take some experience to learn what clothing and equipment you need at certain temperatures. You warm up quickly as you start walking, and that down jacket can suddenly feel like overkill. However, you need to be aware of forecasted temperatures at all altitudes. Temperatures decrease rapidly as you climb. The temperature at the top of a peak can be significantly lower than at the foot of the mountain. Consequently, always check the temperature at the summit if you plan to climb a mountain.

There is also a big difference between the expected high for the day and the actual temperature on the ground. A brief burst of sunshine can skew the expected high, while cloud cover can lower temperatures considerably. Finally, recognise you may not always be moving. What if there’s an injury and you have to wait for assistance? Suddenly that down jacket looks a lot more appealing…

Precipitation

For most of the year, rain is the main form of precipitation to watch out for. However, come the colder months, snow is also a concern. While you can protect against the rain with a good set of waterproofs, think about the impact on your enjoyment. Sometimes, shortening a rainy walk may make for a more pleasant experience.

You also need to consider the effect of rain on the terrain you are moving through. Heavy rain can swell rivers, making them impassible. It can lead to boggy conditions underfoot that slow or prevent progress entirely. It can make rocks and other features more slippy, making exposed features more dangerous.

Snow can impact your outdoor adventures more drastically. For instance, snowy conditions may require specialist equipment, such as crampons, and an entirely new set of outdoor skills.

Finally, it pays to keep track of precipitation and other weather conditions in the lead up to your walk. It may be dry on the day but if it rained all the previous week, you’re still likely to experience wet conditions underfoot. Similarly, historic weather conditions will influence the snowpack and whether you will encounter treacherously icy conditions on the mountain.

Visibility

On a bright, clear day, consider sun cream and extra water to ensure you stay hydrated. At the other end of the spectrum, mist and low cloud conditions can result in low visibility, obscuring landmarks you usually use to navigate. In these instances, the ability to navigate via map and compass is critical.

Air mass movements

Weather in any given area is often the result of conditions thousands of miles away that drive air masses and weather fronts across the seas and oceans to land on the shores of the UK. Where these weather fronts originate from can determine the general feel of the weather in your local area.

For instance, the Tropical Maritime Air Mass comes from the southwest, across the Atlantic, and brings warm, moist air that results in mild weather and cloudy and rainy conditions. On the other hand, the Polar Continental Air Mass comes from the east, across Central Europe, and is typified by hot air and dry conditions in the summer and https://www.raw-adventures.co.uk/blog/wp-admin/index.phpcold air and snow in the winter.

When looking at air masses, it is important to recognise that these weather patterns are generalisations. Other factors can impact the way weather manifests. They give you an insight into longer-term weather trends but are not the most accurate way of determining weather on any given day.

Ask local experts

Finally, we always recommend talking to local experts when unsure about weather conditions. Hilly and mountainous terrain is often home to changeable weather conditions and microclimates that the weather forecast does not always necessarily account for.

Talking to a local with long-term experience of the weather in the area can be a great way to enhance other forecasts.

In Eryri, RAW Adventures are the local experts. We have spent years exploring the region and organising a wide range of adventures, challenges, skills courses and group excursions that enable visitors to experience Yr Wyddfa (Snowdon) and the surrounding area in all its glory.

If that sounds like something you would enjoy, check out our amazing Eryri adventures or our skills and qualifications courses. Alternatively, get in touch with the friendly RAW team if you have any questions.