The storm formed from a tropical wave that moved off the west coast of Africa on 22 September, growing larger in size over the course of its development.

After completing the cycle, Lorenzo rapidly restrengthened, peaking at Category 5 intensity on 29 September with 1-minute sustained winds of 160 mph.

The extratropical cyclone moved quickly towards Ireland and the United Kingdom and became the first named storm of the 2019–20 European windstorm season, before eventually dissipating on 7 October.

Through late September and early October, large swells were generated by the hurricane's massive wind field, impacting much of the Atlantic basin.

The French ship Bourbon Rhode capsized amid the violent seas on 27 September; among its 14 crew members, three were rescued, four drowned, and the remaining seven are presumed dead.

The extratropical remnants of Lorenzo then affected Ireland and the United Kingdom on 3 and 4 October, bringing gusty winds and heavy rains.

As Lorenzo began to turn slowly northward, the hurricane weakened with the onset of an eyewall replacement cycle and intrusions of dry air.

[2] Although restrengthening was not forecast due to moderate wind shear and low ocean heat content, Lorenzo defied expectations and rapidly reintensified into a Category 4 hurricane upon completing its eyewall replacement.

[2] Continuing to intensify, Lorenzo reached Category 5 strength at 03:00 UTC on 29 September,[2] becoming the easternmost hurricane of such intensity recorded in the Atlantic basin, surpassing Hugo in 1989.

On 4 October, Lorenzo's remnant made landfall on Ireland, and the low-level circulation center of the cyclone became ill-defined shortly thereafter.

[9] Additionally, Lorenzo spent more days as a major hurricane east of 45th meridian west than any previous cyclone on record, surpassing Carrie of 1957.

Search and rescue resumed on 9 October, albeit at a much smaller scale, after calls to French authorities by the Croatian and Ukrainian governments.

[2] On 4 October, relatives of crew members and people who worked on the vessel indicated that repairs on the ship were incomplete and it was not ready for a trans-Atlantic voyage.

[11] Despite being over 2,000 mi (3,200 km) away from the storm, United States National Weather Service (NWS) offices in Florida and North Carolina warned that the swells from Lorenzo could cause rip currents and beach erosion.

[20] Early on 30 September, the Instituto Português do Mar e da Atmosfera (IPMA) issued hurricane and tropical storm watches for the Azores,[21] which were upgraded to warnings later that day.

[23] On 3 October, the government of the Azores declared an "energy crisis situation" in Flores and Corvo due to difficulties in supplying fuel to the two islands.

[30] On 3 October, the extratropical remnants of Lorenzo passed over an M6 Buoy, which is located about 250 mi (400 km) west of Mace Head in Galway, recorded a pressure of 969 hPa (28.6 inHg).