We are due to go from hot, sunny weather, to heavy rain and storms in the next few days

Wow, how lucky we are to have had at least two weeks of hot and sunny weather!
No rain to worry about, just lovely dry weather and roads.
With the threat of rain and maybe thunderstorms arriving either today or tomorrow, many drivers may be caught out dry, "grippy" tarmac suddenly becoming very greasy and slippery in the damp conditions.
We will need to brake and steer gradually, until we know how much grip there is on the roads. 
When was the last time that you used your windscreen wipers? Are they still working properly, or have they cracked and torn in the dry weather, and now they cannot clear the windscreens so that you can see what's happening around you?
Have you still got enough windscreen washer fluid  to clean any grease off the windscreens?

How much tread have you got on each of your tyres? And what about the spare tyre? And what about the pressure in each tyre?
It might be very worthwhile just making sure your car is ready for bad weather, as well as the good weather we have been having recently.
http://www.andrewknightdriving.org.uk/driving-in-rain.html