Does this sound okay?
"Due to expectedly inclement weather conditions..."
I am especially interested in the use of "expectedly."
It's really just a matter of context (i.e. - the intended meaning).
If the weather condition being spoken is in the future, but the forecast says it will be inclement when it does arrive (so you're cancelling the village fete, or whatever), then of course it's expected.
But if the predicted weather has already started, it's perfectly grammatical to say it's expectedly inclement, if in fact that's what it is (in line with prior expectations). OED defines...
expectedly adv. in the manner expected, according to expectation;
Note that as J.R. says, expectedly is very rare compared to unexpectedly. We usually use as expected when that's the syntactic functionality we want (effectively, He appeared as expected is adverbial usage).
But if we reverse the expectations (and use simpler meteorological terminology), I have no problem with...
1: Due to unexpected bad weather the fete has been cancelled
2: Due to unexpectedly bad weather the fete has been cancelled
It should be fairly obvious that in #1 we weren't expecting bad weather at all (maybe the forecast said it would be sunny). Whereas in #2 we knew the weather would be bad (but we probably hadn't expected it to be so bad we'd have to cancel the fete). Unexpectedly, it was even worse than we had anticipated.
I must admit I don't know why we prefer as expected over expectedly in nearly all cases. It may be connected to the fact that we have many alternatives (naturally, obviously, predictably, typically, clearly, foreseeably, logically, etc. plus phrases like it goes without saying).
Such words are often used in sensitive/loaded contexts, so it's likely people learn to be extra careful with them. Perhaps expectedly is avoided because it raises the question of expected by whom? in too many contexts where we'd rather be more circumspect. So we tend to opt for more "impersonal" alternatives.
Expectedly inclement is an odd word pairing. When I did a Google search on it, I found 8 hits – all but one of them was tied to a user named Julie on the Stack Exchange network. Here's the one that wasn't:
My time behind the wheel didn’t provide the opportunity to verify these figures — the expectedly inclement Scottish weather and slow-moving traffic proved insurmountable — but it did provide ample evidence that the car has significant reserves of power.
My first thought was that expected weather seems more natural than expectedly weather, and the inclusion of word inclement does not affect that.
Due to expected inclement weather conditions, we are canceling tomorrow's picnic.
If you use the adjective expected – instead of the adverb expectedly – then it sounds just fine.
However, as others mentioned, there are some cases where your clause could work. It's a bit tricky, though, because expected (or expectedly) inclement weather could refer to weather conditions in the present, past, or future, and which one you're referring to might affect whether or not expectedly inclement is the right way to describe it.
Also, it's worth noting that the word expectedly is much rarer than the word unexpectedly. Maybe that's to be expected?