Tropical Storm Arthur was a strong off-season tropical cyclone that impacted the East Coast of the United States in May 2020. The first of thirty-one depressions and thirty different named storms of the extremely active 2020 Atlantic hurricane season, Arthur marked the record sixth consecutive year in the Atlantic basin with a tropical cyclone forming before June. It was one of two off-season storms in the season, alongside short-lived Tropical Storm Bertha. Arthur originated from a front that stalled over the Straits of Florida on May 10, which slowly drifted south for two days. The system became a tropical depression on May 16 north of The Bahamas. A day later, the system intensified into a tropical storm and was named Arthur. Arthur gradually intensified while tracking towards the Outer Banks of North Carolina, attaining its peak intensity with maximum 1-minute sustained winds of 60 mph (97 km/h) and a minimum central pressure of 990 mbar (29 inHg) on May 19, before skirting the region and becoming an extratropical cyclone. The cyclone then accelerated towards Bermuda and dissipated on May 21.

The 2020 Atlantic hurricane season was the most active Atlantic hurricane season on record, in terms of number of systems. It featured a total of 31 tropical or subtropical cyclones, with all but one cyclone becoming a named storm. Of the 30 named storms, 14 developed into hurricanes, and a record-tying seven further intensified into major hurricanes. It was the second and final season to use the Greek letter storm naming system, the first being 2005, the previous record. Of the 30 named storms, 11 of them made landfall in the contiguous United States, breaking the record of nine set in 1916. During the season, 27 tropical storms established a new record for earliest formation date by storm number. This season also featured a record ten tropical cyclones that underwent rapid intensification, tying it with 1995, as well as tying the record for most Category 4 hurricanes in a singular season in the Atlantic Basin. This unprecedented activity was fueled by a La Niña that developed in the summer months of 2020, continuing a stretch of above-average seasonal activity that began in 2016. Despite the record-high activity, this was the first season since 2015 in which no Category 5 hurricanes formed.