On the strength of these two new stories, I'd say quite a lot !

Exhibit A: what can happen when too little rain falls?

New Zealand is facing a power crisis, because a two year long drought which has drained the reservoirs that were providing 75% of that island nation's electricity. Now their contribution has fallen to just 50% and the Kiwi government is asking its citizens to cut back on electricity use. Alas, hydropower is not 100% reliable because you can't guarantee and make long-term predictions about rainfall. So if blackouts do ensure in NZ, you wonder what's going to  happen to Trustpower, NZ's vertically integrated retailer and hydro asset owner of hydroelectricity, listed on their stock exchange (unfortunately, no yet on advfn). Any country over-exposed to hydropower runs this risk - indeed, such was the case with Norway (which has 27 GW of hydro) a few years ago. But by and large, it's still a small risk.


Exhibit B: so what about when too much rain falls?

Analysts at BMO Capital Markets and Citigroup have cut their stock ratings on ethanol makers and corn refiners in America's midwest because of massive flooding in that region which is widely thought to affect this year's crop. They are anticipating there won't be enough corn to go around (which suggests to me the price of ethanol will go up) for them to work on. This downgrade has so far affected Archer Daniels Midland and VeraSun Energy amongst others.

So there you go, investors can - like the late 80s pop group Milli Vanilli - blame it on the rain. It's just a pity that  New Zealand and America's Midwest can't swap their weather !