However, the ground conditions should not have a bearing on rider's performances, she said.
"It will be make for a softer landing if anyone happens to fall off."
The Norwood Cup was the showcase of yesterday's competition. The historic trophy was the first of the big events at HoY with most competitors in Sunday's Olympic Cup using this event as a warm-up class.
Equestrian competition manager Toni O'Kane said while the day ticked along nicely it was very wet.
"We've gone from one extreme to the other."
Ms O'Kane said there would be a bit of ground prep to do as organisers dealt with the deluge of water on the arena.
"It's been a good start to the week, but now we just want the sun to come out."
Spectator Shayla Macdonald wasn't letting the rain dampen her high spirits.
"It's my favourite event of the year, I'm so stoked to be here."
The Nelson native has been to the last eight HoY events, but this year had special significance as she was watching her daughter Alexis compete in the show jumping for the first time.
"The competition has been strong so far, Alexis will need to be on form."