A period of renewed rapid intensification brought Kirk to peak intensity as a Category 4 hurricane on the Saffir–Simpson scale, with winds of 230 km/h (145 mph), on 4 October.

Gradually curving to the northeast, Kirk weakened after peak intensity due to cooler sea surface temperatures, dry air, and wind shear, while also gaining size with latitude; it became an extratropical cyclone on 7 October.

[5] The next day, the NHC began monitoring a broad area of low pressure associated with a tropical wave producing limited shower activity west of Cabo Verde, noting that environmental conditions were favourable for development.

[10] The depression strengthened into Tropical Storm Kirk at 15:00 UTC on 30 September, with satellite microwave imagery from a few hours earlier indicating that a nascent core with a partial eyewall had formed.

[11] Shortly thereafter, Kirk's intensification paused, its structure improving little as it tracked west-northwest along the southwestern edge of the subtropical ridge.

Signs of dry air on Kirk's western flank remained apparent, possibly introduced by some northerly mid-level shear.

[13] Kirk's structure continued to improve on microwave imagery, and the storm intensified to a Category 1 hurricane at 21:00 UTC that day.

[14] After an intrusion of dry air briefly interrupted further intensification,[15] continued improvements to Kirk's structure signalled a resumption in strengthening throughout 2 October.

[16] Kirk then initiated an episode of rapid intensification, becoming a Category 3 hurricane at 00:00 UTC on 3 October,[17] with satellite imagery displaying a ragged eye surrounded by multiple rotating convective bursts.

[20] Kirk then strengthened to its peak intensity early on 4 October, with sustained winds of 230 km/h (145 mph) and a minimum central pressure of 934 mbar (27.6 inHg); the NHC noted a well-defined circular eye 37 km (23 mi) wide surrounded by a ring of deep convection.

[23] Southwesterly shear and intrusions of dry air additionally contributed to weakening, with Kirk falling to Category 3 intensity at 09:00 UTC on 5 October.

At the same time, the hurricane began a northward turn, influenced by a shortwave trough placed over the west-central Atlantic and the subtropical ridge to its east.

[24] Kirk then weakened further to Category 2 intensity 24 hours later under the effects of increasing southwesterly shear, the vertical structure of its core becoming disrupted as a result.

[30] The NHC issued advisories saying that waves from Kirk could create life-threatening conditions in Bermuda and the East Coast of the United States.

[31][32] A red alert was issued in the western group of the Azores as swells generated by a weakening Hurricane Kirk were projected to batter the coastline.

Weather and civil protection officials, who had predicted winds of up to 75 mph (120 kilometres per hour) and heavy rain, placed the coast on a yellow alert as waves reached up to seven metres (23 feet) high.

[49] Spanish weather officials issued an orange alert for the north and northwest of the country, warning of winds up to 87 mph (140 kilometres per hour) in the Asturias region.

Portugal's civil protection authority reported over 1,300 incidents from Tuesday night to Wednesday, with three-quarters involving fallen trees in the north.

Spain also experienced heavy winds and rainfall, with waves as high as seven metres crashing ashore, according to local media.

Strong gusts caused delays and cancellations in rail and air services, park closures, collapsed roofs, and damage from fallen trees.

[58][62] In southern France, a storm swell near the port city of Sete, Hérault overturned three boats, killing one amateur sailor and leaving another two in critical condition.

[63] Additionally, 64,000 people in the south of France were left without power, as reported by Enedis to AFP, while several departments saw roads cut off by floodwaters.