Daniel Ricciardo has stayed on top during the last hours of the first day of testing at the Barcelona-Catalunya Circuit. The Australian driver has not improved during the afternoon since weather conditions have got worse. Light rain and cold have caused have almost stopped the teams from doing any lap.
Fernando Alonso has been the only driver who has improved his best time from the morning session. The Spaniard has gone on track in the afternoon to recover the time lost after his incident on the morning session, on which he has only been able to do ten laps. The two-time world champion has improved to fifth place, between both Renaults. Carlos Sainz has driven for the French team during the afternoon and has done 26 laps to get sixth place.
There has also been a driver change in Mercedes. Valtteri Bottas had taken the second best time in the morning after 58 laps, and Hamilton has got into the car in the afternoon to complete 25 laps and end up in seventh position. Actually, given the situation, the reigning champions has been unable to take any profit from his laps.
Sergey Sirotkin has made his debut as a Williams main driver, but his adaptation to the car has not been successful due to the conditions. The Russian driver has been unable to set a competitive lap time and has only got some mileage after doing 23 laps, many of them with the intermediate tyres.
One of the most surprising things that have been seen today is the Toro Rosso progression with the Honda engine. Brendon Hartley has done more than 90 laps and displayed a solid reliability on this day of testing. Very different from what McLaren suffered with them last year.
Ricciardo has finally been the driver with most laps and the only one to go on track with full wet tyres. Sirotkin and Alonso did some laps with the intemediates to end a session with few activity on track. After Red Bull, Renault has been the team with the most laps, with 99 between both drivers.
The weather forecast is even worse for the upcoming days. Cold and rain are expected for tomorrow and Wednesday. It could even start to snow soon. If everything goes with no problem, which is not expected to happen, the season will start tomorrow at 8.00 in the morning.
Final results:
| Pos. | Nº. | Driver | Team | Time | Laps |
| 1 | 3 | Daniel Ricciardo | Red Bull | 1:20.179 | 101 |
| 2 | 77 | Valtteri Bottas | Mercedes | 1:20.349 | 58 |
| 3 | 7 | Kimi Räikkönen | Ferrari | 1:20.506 | 80 |
| 4 | 27 | Nico Hülkenberg | Renault | 1:20.547 | 73 |
| 5 | 14 | Fernando Alonso | McLaren | 1:21.339 | 47 |
| 6 | 55 | Carlos Sainz | Renault | 1:22.168 | 26 |
| 7 | 44 | Lewis Hamilton | Mercedes | 1:22.327 | 25 |
| 8 | 28 | Brendon Hartley | Toro Rosso | 1:22.371 | 93 |
| 9 | 18 | Lance Stroll | Williams | 1:22.452 | 46 |
| 10 | 8 | Romain Grosjean | Haas | 1:22.578 | 55 |
| 11 | 9 | Marcus Ericsson | Alfa Romeo Sauber | 1:23.408 | 63 |
| 12 | 34 | Nikita Mazepin | Force India | 1:25.628 | 22 |
| 13 | 35 | Sergey Sirotkin | Williams | 1:44.148 | 24 |