The weather is a national obsession, and never more so than during a time of extremes. A summer heatwave may be a dream come true for sun worshippers, but the sweltering heat can cause or exacerbate health problems and leave commuters gasping for air.
With a Samsung GALAXY S4 in your pocket you can always take the weather with you – or at least an array of apps and widgets to keep you well informed about the current state of the climate. They'll also help predict whether you need to slather on factor 50 sunblock or pack a brolly for the inevitable downpour.
How weather apps work
"To forecast the weather you are trying to predict an inherently chaotic system," explains Charles Ewen of the UK's Met Office.
"About half the work that anyone does to forecast the weather is in capturing and understanding the current state of the atmosphere. That has to be done on a global scale – you can't forecast in the UK for any length of time without some knowledge of what is going on in the rest of the world."
The Met Office is one of the primary sources for the weather data used by smartphone apps. It is a key part of a global network of meteorological agencies, coordinated by a United Nations group called the World Meteorological Organisation (WMO).
"The Met Office is a world leader in this and there are about ten or so modelling centres of similar capability around the world," says Ewen. "We also need knowledge of how the atmosphere works, and that comes down to science. That's physics, and especially maths – for example fluid dynamics, as the atmosphere is, to all intents and purposes a fluid.
"Another thing the Met Office does is run a very active and collaborative science program, to some extent with the WMO but largely with academia, to better understand the state of the atmosphere."
Open APIs and crowdsourced weather apps
This kind of academic data is usually publicly available – the Met Office has an open application programming interface, or API, called DataPoint, which is a sort of interface for apps and web services to grab the latest data and predictions from the Met Office's climate models.
The same data is therefore used by both the official Met Office app and many others, such as the BBC Weather app. The difference comes down to presentation and the kind of information each app chooses to give to the user.
Several other commercial apps use their own privately gathered and analysed data. One fast-growing area is so-called crowdsourced data. Until recently, this relied on a combination of observations and weather data from enthusiasts' personal weather stations. A new wave of smartphone apps has arisen, however, that uses actual sensors built into phones to gather hard data and collate it for analysis.
The Samsung GALAXY S4 is particularly well suited for this, which is why it has been singled out as the ideal platform for a new app called WeatherSignal.
Samuel Johnson, of WeatherSignal's parent company OpenSignal, explains: "The GALAXY S4 is perfect for our purposes simply because of the sheer number of sensors it contains. It's the first major feature phone to contain both a hygrometer and a thermometer (making it perfect for taking weather readings). We can take readings from the GALAXY S4 that we can't take from any other smartphone, helping to make our live weather map even more complete."
WeatherSignal currently has around 30,000 active users. "The feedback from users has been fantastic," says Johnson. "Everyone seems to have really got on board with the idea that we're trying to do something that's never been done like this before – a properly localised crowdsourced weather map.
"Also everyone seems fascinated by the fact that they can take readings of magnetic flux, probably because it's something unusual that they hadn't thought about before – but its definitely been surprising to see people enjoying that particular sensor reading so much!"
From basic predictions to actual collecting of data, then, there are a lot of apps out there. We take a look at the best ones to use on your GALAXY S4.
1. S Health
Samsung's built-in health and fitness app makes use of those extra sensor built in to the GALAXY S4 to provide an at-a-glance reading of the weather conditions in your precise location, so you can see easily if there is anything that could affect your health.
The official Met Office weather app is packed with data and uses the very latest predictive models from the Met Office to show you what you can expect from the elements.
Unlike some commercial apps, the Met Office is very keen to only show you what can realistically be predicted with the current data. You can't zoom down to show the weather in your garden or predict precisely if it will rain in 10 minutes' time – although some rival apps will pretend that they can.
AccuWeather is a commercial weather forecasting company that uses its own data and predictive technology. It claims to be able to predict up to 15 days in advance in this free version and up to 25 days ahead in the paid app (£1.92).
If it is long-term weather predictions that you are after then we recommend that you give AccuWeather a try to see for yourself.
WeatherSignal works on most Android phones but is designed specifically to take advantage of the advanced environmental sensors built into the GALAXY S4.
"We're really excited about the potential for using a network of mobile phones to map live weather conditions," says WeatherSignal's Samuel Johnson. "And so we only use data collected from our users – we don't supplement it in any way. There are already lots of services which use satellite or weather station information, we wanted to do something completely different."
6. Samsung Weather Widget
Possibly the easiest to open of any of the apps here as it comes built into the GALAXY S4.
Nevertheless, this great looking widget can provide a quick at-a-glance weather report on your homescreen, as well as the ability to tap through for more information. Some great animations too.
One of the season's hidden dangers is the release of pollen, which can cause misery for hay fever sufferers.
This clever app – also derived from Met Office data and sponsored by antihistamine brand Clarityn – maps the pollen levels across the country and highlights areas where you'll need an extra pack of tissues.
This app is actually an overlay for Google Maps, allowing you to superimpose Weather, Satellite data, Temperature, Humidity or Wind direction on top of a Google Maps view.
The app is still in the beta stages and the data isn't that fine-grained yet, but it is useful for an overview and Weather Maps could well develop into something more interesting when it officially launches.
The first "internet weather service" operated from the University of Michigan, Weather Underground is now a commercial company. It uses data from various publicly available sources as well as crowdsourced data from enthusiasts' weather stations, plus its own predictive models, to create weather reports for across the world.