OK, the last bit was an oversimplification.
As I write in the formerly sunny Norwood it has started pelting down. Obviously I don't need a piece of technology to tell me this. Last week, however, a family member was suffering a little with breathing issues due to pollen - we live opposite a microscopic park (already my home sounds posher than it is) and if you have hay fever this can become very difficult, particularly combined with an unkempt (read 'completely neglected for years) garden next door.
So an indoor and outdoor gadget that tells you what the air quality is like is something of a help. You can monitor temperatures and air quality through the apps, which are of course free, and set alerts when they reach a certain level.
For £139 it could be an expensive way of seeing whether it's raining or not if you're not all that worried by the temperature. In the current heatwave, however, if you're prone to breathing issues it could be a very good investment - and you can buy extra modules to monitor different rooms if, say, you have kids.