When I was prepping for a backpacking trip in New Mexico (Philmont), I was advised to be prepared for 35F and raining. It sounds like that' what the OP was looking for - what does he need to be prepared for? Couldn't someone just give the poster that kind of answer? I don't think that's too much to ask, and it wasn't an unreasonable question. Quite a good question, actually.
We may have scared him off -- you'd think he'd asked for the best chain lube by the passions the poor guy provoked. But I agree it's a good question.
It's probably useful to be aware of the extremes for the week at a given location, but overkill to expect it. A few years ago a late frost hit the last week in April and killed back all the trees; first time in over 100 years a local orchard produced nothing. Would you expect it? Only if you're gunning for the "most pessimistic" title. Have a plan to deal with it? Probably a good idea, either find a motel or put on all your clothes, hat, warm gloves, and shiver out the night.
Using the weatherspark.com data for instance, would it be better to plan for 75% high/25% low, or 90% high/10% low? Forget the average -- the conflation with "normal" in the statistical sense of the average, and the usual sense of "normal" as what you'd expect, is egregious in the weatherman's patter. On average, the temperature is not average.