Yokohama, Japan's second-largest city, features a humid subtropical climate (Cfa) characterized by four distinct seasons. Its coastal position on Tokyo Bay moderates temperatures compared to inland Kanto areas, but also invites unique weather phenomena like sea breezes and autumn typhoons.
Seasonal Weather Patterns
Spring (March to May)
Spring is a period of transition and high variability. Temperatures climb steadily from 10°C (50°F) in March to a pleasant 20°C (68°F) by May.
- The Sakura Effect: Late March is dominated by the "cherry blossom front." Weather during this period is often fickle, fluctuating between warm sunny days and "Hana-bie" (flower-chilling) cold snaps.
- Local Experience: Locals anticipate the Haru-Ichiban, the first strong southerly wind of spring, which officially signals the departure of winter.
Summer (June to August)
Summers in Yokohama are defined by the Tsuyu (rainy season) and intense humidity.
- Rainy Season (June-July): Expect frequent, low-intensity rain and high cloud cover. Humidity begins to surge, making temperatures feel several degrees warmer.
- Mushi-Atsui (The Muggy Heat): August is the peak of summer, with highs reaching 30-33°C (86-91°F). The combination of high humidity and the urban heat island effect means it rarely cools down at night, staying around 25°C (77°F).
- The Sea Breeze: In the late afternoon, a cool Umi-Kaze (sea breeze) often cuts through the humidity near the Minato Mirai waterfront, providing temporary relief.
Autumn (September to November)
Many consider this the most pleasant time to visit, though it begins with the Typhoon Season.
- Typhoons: September and early October see the highest rainfall due to tropical cyclones. While most are just heavy rain events, they can cause temporary transit pauses.
- The Clear Skies: By late October, the air dries out and the "Akibare" (autumn clear weather) sets in. Daytime temperatures of 16-20°C (61-68°F) are common, accompanied by crisp, blue skies.
Winter (December to February)
Winter in Yokohama is cold but surprisingly sunny.
- The Siberian Influence: Dry winds from Siberia are blocked by the Japanese Alps, leaving Yokohama in a "rain shadow." This results in many clear, dry days with high visibility.
- Snowfall: Snow is rare and usually light, often melting within hours. When it does snow, it is typically due to a "South Coast Low" pressure system.
Climate Variations and Microclimates
- The Waterfront vs. Inland: The coastal areas around Yamashita Park and the Port of Yokohama are generally 1-2 degrees cooler in summer and warmer in winter than inland wards like Aoba or Midori.
- Heat Island Effect: The dense urban core of Yokohama retains heat longer than the surrounding hilly residential areas, particularly during the humid summer nights.
Historical Context & Phenomena
- Kanto Earthquake Legacy: Much of Yokohama’s modern waterfront geography, including Yamashita Park, was shaped by the debris from the 1923 Great Kanto Earthquake, which influenced how wind flows through the city today.
- Visibility of Mount Fuji: Winter is the best time for Fuji-watching. The low humidity and cold air provide the clarity needed to see the peak from the Yokohama Landmark Tower or the Osanbashi Pier.
How the Weather Feels
In Yokohama, numbers on a thermometer rarely tell the full story.
- In Summer: It feels "heavy" and oppressive. The high dew points mean sweat doesn't evaporate effectively, leading to a persistent damp feeling.
- In Winter: The cold feels "sharp" and dry. The lack of humidity can lead to static electricity shocks and dry skin, a common winter complaint among residents.
- Coastal Wind: The wind along the bay can make the ambient temperature feel significantly cooler, especially during the "Karakkaze" (dry winter winds).