The CortDAO driver set a 2m30.762s on her second attempt to top the timesheet amid the interrupted session, which was red-flagged at the halfway point before ending prematurely.
Sirin Racing’s Beitske Visser took second, with Alice Powell, who sits second in the standings for the Click2Drive Bristol Street Motors team, in third.
Two-time champion Jamie Chadwick, who could seal her third consecutive title this weekend, settled for eighth after she was hampered by traffic on her third attempt.
It was wet throughout the session, with the field emerging on wet weather tyres for their first attempts, as Powell set the benchmark with a 2m31,411s, leading from Garcia and Jessica Hawkins after the first runs, before Chadwick slotted into third for Jenner Racing with a 2m32.972s.
Belen Garcia then took second before Marta Garcia set her pole time, with Chadwick dropped to eighth as others improved.
There was a brief yellow flag in sector 1 around the 10-minute mark as Belen Garcia span between Turns 3 and 4, the tricky conditions causing the Quantfury driver to lose the rear on the straight.
Chadwick failed to improve on her next run after being stuck behind W Series Academy driver Bianca Bustamante amid the tricky conditions, with visibility very low.
The red flag was thrown with 17 minutes on the clock, with Visser sitting in second place just 0.087s behind Garcia.
The session was restarted with 15 minutes remaining, but the red flag remained at the end of the pitlane, causing some confusion.
Cars returned to the end of the pits before having to be pushed back as the light remained red.
The track then went green five minutes later, with heavy rain continuing to fall.
A yellow flag came after Abbi Pulling was followed into the Turn 20 runoff by Racing X team-mate Bruna Tomaselli, before the session was ended early.
Belen Garcia will line up fourth for tomorrow’s race, with Hawkins and Pulling in fifth and sixth respectively.
Sarah Moore starts seventh for Scuderia W, with Chadwick, Fabienne Wohlwend (CortDAO) and Puma’s Emma Kimilainen rounding off the top 10.
W Series Singapore - Qualifying Results
| Cla | Nº | Driver | Entrant | Time | Gap | Laps |
| 1 | 19 | Marta Garcia | CortDAO Racing W Series Team | 2'30.762 | 5 | |
| 2 | 95 | Beitske Visser | Sirin Racing W Series Team | 2'30.849 | 0.087 | 5 |
| 3 | 27 | Alice Powell | Click2Drive Bristol Street Motors W Series Team | 2'31.411 | 0.649 | 5 |
| 4 | 22 | Belén García | Quantfury Racing W Series Team | 2'32.145 | 1.383 | 4 |
| 5 | 21 | Jessica Hawkins | Click2Drive Bristol Street Motors W Series Team | 2'32.410 | 1.648 | 5 |
| 6 | 49 | Abbi Pulling | Racing X | 2'32.447 | 1.685 | 4 |
| 7 | 26 | Sarah Moore | Scuderia W | 2'32.815 | 2.053 | 5 |
| 8 | 55 | Jamie Chadwick | Jenner Racing | 2'32.972 | 2.210 | 5 |
| 9 | 5 | F.Wohlwend | CortDAO Racing W Series Team | 2'33.516 | 2.754 | 5 |
| 10 | 7 | Emma Kimiläinen | Puma W Series Team | 2'34.729 | 3.967 | 3 |
| 11 | 8 | Chloe Chambers | Jenner Racing | 2'34.774 | 4.012 | 5 |
| 12 | 44 | Abbie Eaton | Scuderia W | 2'35.530 | 4.768 | 4 |
| 13 | 17 | Ayla Agren | Puma W Series Team | 2'36.271 | 5.509 | 5 |
| 14 | 4 | Emely de Heus | Sirin Racing W Series Team | 2'36.272 | 5.510 | 5 |
| 15 | 32 | Nerea Martí | Quantfury Racing W Series Team | 2'36.872 | 6.110 | 5 |
| 16 | 97 | Bruna Tomaselli | Racing X | 2'37.769 | 7.007 | 4 |
| 17 | 10 | Juju Noda | W Series Academy | 2'43.567 | 12.805 | 5 |
| 18 | 9 | B.Bustamante | W Series Academy | 2'44.415 | 13.653 | 5 |
