Before the trip

As a trip leader, there is often a string of practical details to sort out before an outing, and the sooner you get an overview of the expected weather, or of the uncertainty around it, the better placed you will be to prepare the participants for what they will meet on the trip.

The best and simplest way to gather information about the expected weather is to follow the online forecasts well in advance, so that you can keep track of whether the forecasts vary from day to day and from site to site. Over the course of two or three days you will almost certainly have formed a picture of the weather you can expect on the trip.

By clicking ‘details’ on Yr you can bring up an estimate of how much cloud, temperature and wind is forecast. The fog forecast is especially worth noting. Weather forecast: Meteorologisk institutt, screenshot

If all the forecasts agree, you can probably treat the forecast as fairly certain. If they disagree and change a lot, the weather is uncertain, and you must consider whether to seek further information. This applies in particular if the weather affects what you need to bring on the trip (tent or open sky), or if the weather could turn so bad that the trip should be cancelled or moved.

If you are heading for staffed lodges, one tip can be to talk to the people at the lodges about the conditions and how they interpret the forecasts. After all, they have more experience of the weather in the area than you do yourself. You can get extra information by ringing a meteorologist directly. This is often some form of paid service, so here the benefit must be weighed against the need.

The more advanced can try to get into the detail by combining maps and meteograms, to try to form a picture of what is producing the rain on Saturday. Is it the showers? Is it the front of the large low-pressure system? Try also to think about ‘what is the possible variation in the weather – what happens if the low tracks a little further south or north? Will the weather be the same?’.

What can happen

Once you have an overview of what weather can be expected – ideally with the extremes in each direction – you have to think about how it affects your trip. Could the weather become too bad to carry out the trip? If it is winter: what does the weather do to the avalanche danger? What do I do if the weather turns like this? Could the warmth cause snowmelt and flooding? Do we have enough sunscreen? Do we need the tent? Is it worth travelling so far for a trip that will probably be cut short by bad weather? Is it justifiable to go?

There are many questions here, and few of them have a definitive answer, but by thinking them through you will be better prepared for what you will meet along the way. You can help with safety by cancelling, moving the destination or date because the weather is simply too bad where the trip is planned. We do not set out on a paddling trip on the open sea if a strong westerly gale is forecast – or on a long ski tour (topptur) in snow showers, poor visibility and a storm. There is no need to cancel a trip just because a little rain and wind is forecast, but it is important to assess the most exposed trips. Some check questions might be:

• Would I go on this trip privately in this weather?
• Would I bring along on that trip friends who have done little walking in the mountains before?

Keep track along the way

On a trip it is not always easy to catch an updated weather forecast. You can of course update the weather information via countless mobile services, but that requires mobile coverage. You can get a long way by watching the weather around you. Do bring a paper printout or screenshot of the meteogram and keep an eye on it. Note:

• Is the wind blowing from the direction it should?
• Does the change come at the times it was forecast?

If there are differences, they may be because the weather is arriving faster or later than expected, or because the weather system is moving in directions other than the models suggested. If you wish, you can try to interpret what you observe against the information you gathered beforehand. Remember that what is interesting above all is whether there is anything in what you see that could mean danger for the group.

Summer showers

You have surely experienced the weather forecast saying sun while outside it is bucketing down with rain, or hail is rattling on the window. Summer is peak season for heavy showers, and showers are precisely some of the hardest weather to forecast (Meteorologisk institutt, n.d. b).

A shower is a complicated weather system that can develop quickly and then release intense precipitation locally (Meteorologisk institutt, n.d. b).

Be extra alert to showers in summer, therefore, especially in the afternoon and evening (Dannevig et al., 2020).

Shower cloud developing: Cumulus congestus, which can develop further into a Cumulonimbus cloud. Photo: Moonjazz, CC-BY-SA

Dangerous weather

Below are some classic weather phenomena that anyone used to the outdoors will recognise as potentially unpleasant or dangerous. A good deal of weather and many phenomena are not mentioned for reasons of space. For those who are interested, the library and bookshops have a good selection.

Poor visibility

This is perhaps some of the worst weather to get on a trip. When the fog lid sinks over the group or the drifting snow lashes your face, the way to the destination immediately becomes more demanding. Poor visibility in the summer mountains is often linked to the precipitation clouds being so low that they settle down onto the mountain. This is especially common in connection with warm fronts and in situations with high pressure and onshore wind.

In winter it is snowfall, often combined with drifting snow, that is the biggest cause of poor visibility. In the mountains it is the wind in particular that makes the challenges hard. Lighter snowdrift starts at around 6–7 m/s, but from 10–12 m/s the snowdrift often becomes intense enough that it is hard to talk to one another or to find your way.

See the Beaufort scale for a description of common wind conditions in the winter mountains at the various strength grades.

Rain and wind – cold and chilling

‘It is all very well that wet wool keeps you warm – but how wet does it have to get for me to stay warm?’ The combination of water and wind gives a formidable ability to draw heat away from the body, and there are few things as cold as being soaked through and feeling the wind blow through your clothes. Today it is generally possible to dress for the rain. Remember that even though it can be pleasant to walk without rain gear in the light rain down in the valley, the situation can quickly turn worse when you head up into the high mountains.

Severe winter cold

With good clothing and footwear, steady activity and, if needed, face masks, there is hardly any limit to how cold the weather can be and still allow you to go on a trip. But the colder it gets, the greater the demand on these factors, and it often takes only a few minutes standing still before someone in the group gets a white patch on the cheek or loses feeling in a toe. Remember that when the snot freezes in your nose, you are tipping past about -15°C. When the temperature drops below minus 20, even good ski boots will not tolerate much standing still before they get cold. And of course – if a bit of wind picks up, the effective temperature quickly becomes considerably lower.

Next steps

• Weather forecasting — the basics of weather forecasts
• Reading mountain weather — specific to the mountains
• Nature’s weather signs — local signs
• Turning back in good time — decisions at a change in the weather

Learn more

• Yr.no — Meteorologisk institutt’s weather forecast
• Meteorologisk institutt — specialist material and research
• Varsom — hazard warnings (avalanches, floods, landslides)
• Storm Geo — commercial meteorology