Not sure what it's like where you are, but it's pretty much been throwing it down here for almost a week now – which makes it the ideal time to pick up something like the Jump The Gun 60s-style raincoat.
It is what it says it is – styled with an early 1960s look (think Harry Palmer), with no fussy belts or detailing, aside from the usual pockets, but with ample size to keep you (and your suit) covered from the elements.
Three colours available, the blue above or a grey or black, along with plenty of sizes. It retails for £125. Alternatively, keep an eye on vintage and charity shops, these kind of raincoats do occasionally come up, often in really good condition too.