On Sunday the ground was described as good after several drying days - but clerk of the course Andrew Cooper is wary of an uncertain forecast at the end of the week.
If there were no further rain, before the start of the showpiece two-day meeting on Friday, Cooper would anticipate the need for some watering.
But updated weather forecasts from Wednesday onwards have put plans up in the air.
"We've been dry - the last rain we saw at Epsom was on Monday night of last week," said Cooper.
"Temperatures have crept up a bit over that time - (but) I don't think we've ever been warmer than about 22 degrees (yet).
"We've dried out, as anywhere would, and if we were racing today I'd call it good.
"It produced a GoingStick reading of 7.1 - which I think is bang on, historically, good ground at Epsom."
The weather had appeared largely set fair for another week, but showers have popped up on the horizon.
"There is uncertainty as to the forecast for the week as a whole - particularly from Wednesday onwards," added Cooper.
"It looks as if there isn't any confidence at all, talking to meterologists. I don't think they're quite sure what's going to happen, quite how widespread the showers are going to be at the end of the week, which part of the country.
"It's unhelpful uncertainty.
"Going into this weekend, you'd have said it looked pretty settled - but that's what happens, with the weather. We accept that, we've seen it before - it's a sort of unhelpful forecast really.
"You'd far rather know you're either going to see definite rain or none at all - in which case you're that much more in control of things."
Asked whether watering will be in order if the dry spell does persist, Cooper said: "The answer probably is yes - but quite when that will be, what volume etcetera it's impossible to say at the moment.
"We certainly won't be doing anything in the immediate future. We'll sit tight, take stock of things early tomorrow, walk it again, look at the latest forecasts and formulate a bit of a plan going forward.
"I have a guiding principle that there's parts of the course at Epsom you would water the day before but (other) parts that I'd like to give 48 hours to.
"One of the 48-hour parts of the course would be the downhill section - anything from the six (furlong) pole down to the road crossing into the home straight, basically experience has taught us you water that late at your peril.
"It just doesn't quite settle as you'd like.
"So for Friday's racing, that would take us back to Wednesday."
Epsom will aim for a range of going no quicker than good to firm.
Cooper added: "If you've got a drying day, wherever you were at seven o'clock on Saturday morning, it will be something quite different at 4.30 that afternoon.
"I've always said our preparations are really to ensure we don't run the Derby on ground quicker than good to firm - bearing in mind, it's the fifth race of seven at 4.30 on the second day of a two-day meeting.
"What we've got to determine is what ground we should aim for on the Friday - as a starting point, you wouldn't want to be going into racing on ground quicker than good to firm. That would just store up problems for the Saturday.
"So given the uncertainty of a showery forecast, the decision we have over the next 48 hours, is what do we need to do - if anything - to ensure Friday is run on safe, sensible, appropriate ground.
"That doesn't mean it has to be good, doesn't mean it has to be slow side of good - it just means that anything between good and good to firm is (fine)."
The early June weather is set to test Cooper a little this year, but it is an occupational hazard he is used to.
"This sort of forecast poses questions for us - but we've been there before," he said.
"It's not unprecedented weather situation. Some years are very straightforward - but as with any race meeting, you have to work with the weather and you're at the whim of it really.
"Our overriding aim will be to hope to produce the safe, consistent surfaces where horses can perform to the best of their abilities."
Off the course, Cooper reports Epsom is all dressed up to welcome back a permitted crowd of up to 4,000 on Friday and Saturday - and he is confident the two Classics and Coronation Cup will deliver too.
He said: "Overall, things are coming together at the racecourse really well - we're looking forward to welcoming a degree of crowd back to Derby day, after the very surreal one of last year.
"There's a lot of activity (under way) - because a lot of the stuff on the hill comes later in the day, it almost looks like a normal Derby at the moment.
"With the hospitality marquees and other temporary structures that are in use there (already), it almost feels more normal than it is going to be.
"The crowds on the hill and the outer enclosures will always be the big thing that will be missed - but that's just the way we have to do it at the moment.
"I think the races are coming together really well (too).
"It looks a fascinating Derby, Oaks and indeed Coronation Cup - I think they all look really good races to me at this stage."