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Container Lines Struggle Early Year, Rally Through Summer Months

Global container shipping schedule reliability has grown increasingly seasonal since the pandemic. Early-year performance has deteriorated while summer months show marked improvement, according to analysis of vessel arrival data spanning from July 2011 through September 2026.

The study reveals a sharper seasonal pattern than the pre-pandemic era, with reliability now showing pronounced lows at the start of each year before climbing substantially through spring and early summer. Container lines historically experienced modest early-year performance declines followed by gradual improvement, but that trajectory has become more extreme.

Analysts attribute the shift partly to heightened volatility in weekly liner service deployments since 2020. The data also shows a tightening correlation between late arrivals and delay severity, indicating vessels arriving behind schedule now face proportionally larger delays than observed before the pandemic.