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North Atlantic tropical and post‐tropical cyclones impact midlatitude regions, but the inhomogeneous observational record of the latter stages of tropical cyclones precludes many climatological analyses. The frequency of tropical‐origin storms basin‐wide is projected to increase under anthropogenic climate change, so establishing confidence in our knowledge of their historical variability and lifecycles—against which climate model simulations may be evaluated—is important. We used a Lagrangian feature‐tracking algorithm to identify tropical cyclones that impacted Northeast North America and Europe in seven global reanalysis data sets, distinguishing systems that retained warm‐core structures or underwent warm seclusion from those that underwent extratropical transition, acquiring cold‐core, frontal structures. Over the last four decades, ∼25% and ∼10% of tropical‐origin cyclones made landfall across Northeast North America and Europe, respectively, as warm‐core systems, with, on average, higher wind speeds than cold‐core systems. Historical warm‐core and cold‐core landfalls also exhibit distinct tracks, likely responding to differing steering flow and midlatitude conditions. Tropical cyclones and their impacts are not confined to the tropics. In the North Atlantic, the historical record of observed tropical cyclones is probably better than anywhere else, yet even this record is unreliable for storms that originate in the tropics and migrate to the midlatitudes, a particular danger to North American and European coastal regions. Operational collection of pre‐satellite aerial and ship‐based observations has changed over time, and the record of storm landfalls outside the United States is incomplete. These data issues matter because the frequency of tropical‐origin storms across the midlatitudes is expected to increase under anthropogenic climate change, and the basis of any assessment of future risk must be a robust historical understanding. We therefore turned to reanalyses (gridded climate data sets) and an objective storm‐tracking algorithm to identify tropical cyclones that impacted two regions: Northeast North America and Europe. We examined the lifecycles of these storms and their nature and intensity at landfall. Over the last four decades, approximately one in four landfalls over Northeast North America exhibited tropical‐cyclone characteristics, and such storms are associated with high wind speeds, posing a greater risk. For Europe, that number is one in 10, a surprisingly high proportion. How this may change in future will affect populous regions on both sides of the North Atlantic. North Atlantic cyclones originating in the tropics examined across seven reanalysesReanalyses show consistent interannual variability, seasonality, and structural evolution of tropical‐origin cyclonesIntensity evolution and tracks are distinct between warm‐core and cold‐core cyclones North Atlantic cyclones originating in the tropics examined across seven reanalyses Reanalyses show consistent interannual variability, seasonality, and structural evolution of tropical‐origin cyclones Intensity evolution and tracks are distinct between warm‐core and cold‐core cyclones

Post‐tropical cyclones (PTCs) extend many hazards associated with tropical cyclones (TCs) to the midlatitudes. Despite recent high‐impact cases affecting Europe such as Ophelia, little research has been done to characterize the risk of PTCs. Here we compare the climatologies and intensity distributions of midlatitude cyclones (MLCs) and PTCs in the North Atlantic and Europe by tracking cyclones in the ERA5 reanalysis. Considering hurricane season cyclones impacting Northern Europe, PTCs show a significantly higher mean maximum intensity than MLCs, but make only a small contribution to total windstorm risk. Our results show that a disproportionately large fraction of high‐intensity cyclones impacting Europe during hurricane season are PTCs. The fraction of PTCs impacting N Europe with storm force (>25 m s−1) winds is ~10 times higher than that for MLCs. Less than 1% of cyclones impacting Northern Europe are identified to be PTCs. This rises to 8.8% when considering cyclones which impact with storm force winds. Ex‐hurricanes (post‐tropical cyclones; PTCs) can bring hazardous weather such as damaging winds and extreme precipitation to the midlatitudes. The importance of these cyclones for European wind and flood risk is still an open question. By tracking cyclones through 39 years of data, we show that on average, the maximum intensity of PTCs over Europe is significantly higher than that for European windstorms (midlatitude cyclones, MLCs). The difference between the maximum intensity of PTCs and MLCs is larger across Northern Europe than Southern Europe. Our results show that a disproportionately large fraction of high‐intensity cyclones impacting Northern Europe during hurricane season are PTCs. The fraction of PTCs impacting Northern Europe with storm force winds is ~10 times greater than for MLCs. Less than 1% of cyclones impacting Northern Europe during the North Atlantic hurricane season are PTCs. This rises to 8.8% when only considering cyclones which impact Northern Europe with storm force winds. Post‐tropical cyclones are significantly more intense than midlatitude cyclones at their maximum intensity over EuropeThe fraction of post‐tropical cyclones impacting northern Europe with storm force winds is 10 times higher than that for midlatitude cyclonesA disproportionately large fraction of high‐impact European windstorms forming in hurricane season are caused by post‐tropical cyclones