Guides
Guides: understanding the numbers in the weather
Nine forecasts out of ten are read without really knowing what the numbers mean. Here are our deep dives, written to give you a feel for scale.
The basics
What does 8 m/s actually mean? – the whole Beaufort scale translated into everyday observations, the difference between mean wind and gusts, and why the wind feels different in the garden and on the jetty.
How big is three feet, really? – significant wave height, why the odd wave ends up nearly twice as high, and how the length of your boat determines how the sea feels on board.
How much is two millimetres of rain? – millimetres, litres per square metre and intensity per hour, plus what separates drizzle from a downpour.
Deeper dives
Wind chill: why five degrees above zero can feel like minus three – how wind and temperature interact, a table of felt temperature, and when the risk of frostbite begins.
Yellow, orange and red: how weather warnings work – what the warning levels mean in practice, how they differ between land and sea, and what you should do at each level.
Storm-proofing your garden – which objects lift off at which wind strength, a checklist to work through before the blow, and the most common mistakes.
From millimetres to flooding – why 30 mm in an hour is something entirely different from 30 mm in a day, how the ground and drains set the limit, and what you can do at home.
How to read a weather forecast without being fooled – precipitation probability, forecast models, how far ahead a forecast is useful, and why two apps show different weather for the same town.
Snow: from millimetres of precipitation to centimetres of snow – why the same amount of precipitation gives different snow depths, the weight of snow on a roof, and the difference between snow showers and snowfall.
Fog, visibility and when it clears – radiation fog, sea smoke and advection fog, and why the calm, clear night is fog's best friend.
Temperature, humidity and how warm it feels – why humid heat feels worse than dry heat, tropical nights, and the difference between air temperature and ground temperature.
Boating safety: wind, waves and boat size in practice – the relationship between wind and wave height, the choppy seas of shallow water, and when to stay in harbour.
Glossary: weather terms explained – every term from m/s to CAPE, gathered and explained in one place.
See it instead of reading about it
All the guides connect to the visualiser: set a value with the slider, or pull today's actual forecast for your location, and see what it looks like in motion.
Open the visualiserGuides: make sense of the numbers
Deep dives that turn forecast figures into something you can actually see.
Guide
What does 8 m/s actually mean?
Wind forecasts are given in metres per second, but the number rarely means much until you've seen what it does to the world around you. Here's the whole scale in plain terms.
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How big is three feet, really?
Wave height sounds simple until you're standing in a boat trying to decide whether it's safe to head out. Here's what the numbers actually describe.
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How much is two millimetres of rain?
Rainfall is measured in millimetres, but few people have a feel for what the number means in practice. Here's the translation.
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Wind chill: why five degrees above zero can feel like minus three
The thermometer shows one thing, the body experiences another. Wind chill explains why – and when it becomes dangerous.
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Yellow, orange and red: how weather warnings work
Warning levels describe consequences, not just numbers. Here's what they mean and how you should act on them.
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Storm-proofing your garden: what lifts off, and when
Most of what gets damaged in an autumn storm is something the owner could have secured themselves in twenty minutes. Here's the order to do it in.
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From millimetres to flooding
The same amount of rain can be a welcome watering or a basement full of water. The difference lies in time.
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How to read a weather forecast without being fooled
Two apps show different weather for the same location and the same hour. Neither of them is necessarily wrong – here's why.
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Snow: from millimetres of precipitation to centimetres of snow
Five millimetres of precipitation can become three centimetres of powder snow or ten centimetres of heavy, wet snow – the same water content gives completely different snow depths.
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Fog, visibility and when it clears
Fog is a cloud sitting on the ground. Understanding how it forms makes it easier to guess when it will disappear.
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Temperature, humidity and how warm it feels
The thermometer on the balcony and the body's own sense of feel don't measure the same thing. Humidity makes all the difference.
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Boating safety: wind, waves and boat size in practice
The same wind strength can be a pleasant sailing breeze or a dangerous sea, depending on water depth, fetch and the size of your boat.
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Glossary: weather terms explained
All the terms that turn up in weather forecasts and in our guides, gathered in one place.
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