CIRCUIT DE BARCELONA-CATALUNYA | The afternoon session, which was actually not separated from the morning one since there was no lunch pause, started with no driver change in any of the teams that had scheduled it.It was not until 15:00 that Robert Kubica jumped into the Williams to replace Sergey Sirotkin. Mercedes confirmed that Valtteri Bottas would do the entire day.
Sebastian Vettel moved up to the lead thanks to a 1:20.115 which became the quickest lap of the week so far, faster than the time Daniel Ricciardo set on Monday. At that moment, the weather was being quite steady, with 12º C on track.
Two red flags have complicated the first afternoon hour. Charles Leclerc went into the gravel trap at turn 4 and caused the first one, while the second one waved to clean the track at turns 1 and 2.
With an hour to go, the snow that was predicted to fall on the circuit finally arrived. Activity on track stopped, despite the session never had to be actually stopped. Lap times were not improved anymore. Some drivers, such as Kubica, Bottas, Vettel or Max Verstappen, who had to do laps due to his problems during the morning; went on track with this partially snowy conditions and completed a few laps.
Finally, nothing useful could be extracted from this last hour. Vettel remained on top of the table and has the best lap of the week so far. Bottas was second and Stoffel Vandoorne, who was not on track due to a problem with the McLaren’s pipe, ended up in third place. Verstappen, who was one of the most active drivers in the afternoon due to his early issues, ended in fourth position, just one thousandth of a second behind Vandoorne. Haas and McLaren were the teams that struggled the most with reliability and completed the least laps.
If the weather does not stop it, the testing will go on tomorrow at 9:00 in the morning local time.
Final results:
| Pos. | Nº. | Driver | Team | Time | Laps |
| 1 | 5 | Sebastian Vettel | Ferrari | 1:19.673 | 96 |
| 2 | 77 | Valtteri Bottas | Mercedes | 1:19.976 | 94 |
| 3 | 2 | Stoffel Vandoorne | McLaren | 1:20.325 | 37 |
| 4 | 33 | Max Verstappen | Red Bull | 1:20.326 | 65 |
| 5 | 55 | Carlos Sainz | Renault | 1:21.212 | 65 |
| 6 | 10 | Pierre Gasly | Toro Rosso | 1:21.318 | 80 |
| 7 | 40 | Robert Kubica | Williams | 1:21.495 | 39 |
| 8 | 35 | Sergey Sirotkin | Williams | 1:21.822 | 52 |
| 9 | 31 | Esteban Ocon | Force India | 1:21.841 | 78 |
| 10 | 16 | Charles Leclerc | Alfa Romeo Sauber | 1:22.721 | 81 |
| 11 | 20 | Kevin Magnussen | Haas | 1:22.727 | 32 |