Japan Weather by Month: Below Freezing in Sapporo, 21°C in Okinawa — the Same March

In mid-March Sapporo averages a daytime high of 4.1°C and drops to -4.9°C at night. On the same date Naha, Okinawa, averages 21.3°C. One city still has snow on the pavements; the other is T-shirt weather. Japan runs more than 2,000 km north to south, so there is no such thing as "Japan's weather in March".

So this guide treats the five cities Korean travellers visit most as separate places. Tokyo, Osaka and Fukuoka follow Seoul's seasonal rhythm, but their winters are about 7°C milder and their summers more humid. Sapporo's winter is longer than Seoul's; Okinawa barely has one. Every figure is a monthly average of daily data from 2016 to 2025.

The striking thing in the chart is that Tokyo, Osaka and Fukuoka trace nearly the same line. Their monthly highs are mostly within 1°C of each other, so one wardrobe covers a Honshu-and-northern-Kyushu itinerary. Where they differ is how hard summer hits.

• Osaka in August averages 15.6 days above 33°C — more than double Tokyo's 6.4. Kyoto, in a basin, is as hot or hotter.
• Sapporo dips below freezing almost every night in December and January (31 of 31 January nights, 30 in December). In return, July–August highs hover around 25°C: Japan's coolest summer destination.
• Okinawa bottoms out at a 15.7°C nightly low even in January. No winter, but a May–June rainy season and July–September typhoons instead.

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The useful question isn't "which month should I visit Japan?" but "which city, in which month?"

Tokyo's January high is 9.3°C, 7.3°C warmer than Seoul's 2.0°C. Nights hover around freezing rather than far below it, so a wool coat or light down jacket does the job where Seoul calls for a full-length parka. In July and August the gap shrinks to 1–2°C and humidity sits around 80%, which feels much like the middle of Seoul's monsoon.

The rainfall chart is shaped differently from Seoul's. Seoul gets nearly half its year's rain in July and August; Tokyo gets two wet spells — the June rainy season, then autumn rains and typhoons in September–October. October still averages about 13 rainy days, so pack a folding umbrella even for an autumn trip.

Sapporo's January averages -2.5°C by day and -10°C at night. The daytime figure looks like Seoul's, but the real difference is snow: 14–15 days a month in January and February bring at least 1 mm of precipitation, so the city stays white all winter. The Sapporo Snow Festival in early February is the busiest week.

Summer is the mirror image. July–August highs are 25–26°C and days above 33°C are rarer than one a month. The rainy season that soaks Honshu and Kyushu from June to mid-July barely registers in Hokkaido — the Japan Meteorological Agency doesn't even declare a start or end date there. June is one of Hokkaido's most comfortable months.

Naha's nightly low stays above 15°C all year. For a beach trip the variables are the rainy season and typhoons, not temperature. Okinawa's rainy season starts around 10 May and ends around 21 June (JMA 1991–2020 normals), roughly a month ahead of Honshu. The window between the end of the rains and the height of typhoon season — late June to early July — is widely considered the best time for clear water.

Clothing advice follows Tokyo and Osaka's daytime high / nighttime low; Sapporo and Okinawa get temperatures only. As a rule of thumb, dress one season warmer than Tokyo in Sapporo and one season lighter in Okinawa.

1. Cherry blossom — Tokyo and Osaka normally bloom in late March and peak in early April. Sapporo blooms a month later, in early May.
2. Autumn leaves — Kyoto and Osaka peak from mid-November to early December. November, when the leaves coincide with ~17°C days, is this guide's best month for Honshu.
3. Snow and hot springs — Hokkaido in January–February. Rooms fill early for the Sapporo Snow Festival in early February.
4. Beach — Okinawa from late June to early July (right after the rains) or in October (sea still warm, fewer typhoons).
5. Escaping the heat — Sapporo and Hokkaido in July–August; in the big Honshu cities, plan around mornings and evenings.

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Japan's summer heat is about humidity more than temperature. 31°C doesn't look much worse than Seoul on paper; it feels much heavier.

• Period and source: daily values from Open-Meteo's historical weather data (ERA5 reanalysis), 2016–2025, averaged by month at each city-centre coordinate.
• Versus official normals: temperatures generally land within 1–2°C of JMA station normals (1991–2020). Reanalysis smooths out downpours, so monthly rain totals come out lower than gauges and rainy-day counts slightly higher.
• Rainy day: a day with at least 1 mm of precipitation, snow included.
• Best months: a first pass from temperature, rainy days and humidity, then adjusted one step for seasonal factors — blossom, snow festivals, the rainy season, typhoons. It is a judgement call; your mileage may vary.