The all-white Diner en Blanc may have been a washout, but organisers said picnickers got "creative with their dinner plans".
About 1200 people were expected to attend the event, but it was cancelled due to the weather.
The Bureau of Meteorology recorded that 16.6 millimetres of rain fell at Nobbys from 5pm to 10pm on Saturday, amid strong southerly winds.
This made the stage, lighting and sound unsafe, the organisers said.
It was Newcastle's third annual Diner en Blanc, a pop-up picnic event held at a secret address. The event was to mark the start of Newcastle Food Month.
Stockton foreshore was chosen as the event's secret location, at which white-clad attendees were to meet to eat, drink and be merry.
Diner en Blanc organiser Louise Maher said in a statement that the event's mantra was to continue "in all but dangerous weather".
However, guests were given the "option to stay on the coaches for their own comfort".
"It would have been easy to hustle guests off the buses and encourage them to set up, however our guests' comfort was foremost in our minds," Ms Maher said.
"We were as devastated as our guests, many of whom we have got to know personally."
The Herald asked for a comment on whether refunds would be available, but the statement did not address that question.
Alex Morris was due to attend the event with friends Thomas and Aaron.
"We were all dressed in white, with nowhere to go," she quipped.
"We were at The Station and it was still sunny. We were waiting for the bus or ferry and suddenly the sky became overcast," said Ms Morris, who works at Newcastle Museum and writes features freelance for the Herald.
"Everyone was trying to stay optimistic, then the heavens opened right as everyone started walking towards our transportation."
She said two of her dinner companions "didn't have ponchos, so they were hesitant to go".
"We said we'd just hang back for a minute. There were tables and chairs at The Station and we had our picnic table."
The event involved attendees gathering at designated meeting points - with their own tables, chairs, table decorations, napkins, cutlery and picnic baskets - ready to be taken by bus and ferry to the secret destination for dinner.
"Then we started getting texts from other people who were there, our friends, who told us they were trapped on the bus [due to the weather].
"Even though we were disappointed about the rain, we thought our decision to not get on the bus was maybe the best decision we could have made."
They found a spot to have dinner and "made the best of a not great situation".
"We had a picnic at The Station and it all worked out. We had food, we had wine. We were trying to get our friends to come back and join us, as we had several tables set up."
Other groups posted photos on social media of taking the party to an undercover spot on Newcastle foreshore, near Queen's Wharf Hotel.
Some people picked up their food and drink at the Stockton site and began partying in buses, while others took the party to private homes.
"Rain can't dampen our party spirit," Sue-Ellen Brown posted on social media, with photos of a group celebrating around a table and whirling white napkins above their heads, as is the event's tradition.
She told the Herald that her group took the party to a Merewether home, where "smiles and dancing moves" lifted spirits.
A staffer at the event noted on social media that it was a "shame the rain came pouring down as it started off a beautiful day".
"Really felt for the organisers and guests who put so much effort into what would have been a beautiful night, but the guests were still happy to get their wine and food and so positive and didn't let it dampen their spirits."
