The Dutchman reached Q2 for the first time in Formula 1 as he made Caterham's first appearance in the second stage of qualifying this season.
Even though he has won races in his junior career, as well as the Formula Renault 3.5 title, he believes this achievement is up there with anything else he has achieved.
"Yes, it's a big day for me and the team," van der Garde told AUTOSPORT when asked if this was a career high.
"It was a great day for us and I'm very happy and proud of what we did.
"It's not easy in these conditions, but you have to make the most of them and take what you can get."
Caterham judged the conditions well in Q1, opting to bring van der Garde in for fresh intermediate rubber, which allowed him to improve his time by a big enough margin to end up ahead of Paul di Resta and Esteban Gutierrez.
In Q2, van der Garde gambled on a switch to slicks when everyone else was on intermediates. He climbed as high as fifth at one point before being demoted by faster cars that changed tyres later in the session.
"We played it quite aggressive," he said of the team's strategy.
"I was the first one on slicks and it was my call.
"But at those moments, you have nothing to lose and you have to try to get what you can."
Despite being inside the top 10 in the closing minutes of the session, van der Garde believes that he did the best he could have done and that it was impossible to reach Q3 without the rain returning.
He ended up just over a second-and-a-half off the Q3 cut-off time, but believes that there was no more pace in the car because of the conditions.
"The gap to Q3 was quite big," he said.
"It was still wet at the end of Q2 so it was tough and the car was sliding around a lot."
With the Caterham having shown stronger race pace than qualifying pace so far this weekend, van der Garde is hopeful of a good result in Sunday's race.
"You never know - as we saw in the GP2 race on Friday, anything can happen at into the first turn," he said when asked if he felt scoring a point might be possible.