Question 1

How hot does Osaka get in summer?

Accepted Answer

Osaka gets genuinely hot in summer, averaging **28.1°C (82.6°F)** across the meteorological summer of 2025 (June 1 to August 31), with peak temperatures climbing above 39°C (102°F).

August 2025 was the warmest month, with a mean temperature of **30.2°C (86.4°F)**, just ahead of July at 29.8°C (85.6°F). June was noticeably milder at 24.4°C (75.9°F), marking the transition into the hot season. The single hottest reading came in July 2025, when the thermometer hit **39.1°C (102.4°F)**, while August peaked at 38.5°C (101.3°F).

Nights offer little relief in Osaka. Across the summer, nightly lows averaged **20.4°C (68.7°F)** and stayed above 23°C (73°F) in both July and August, the kind of "tropical nights" that make sleeping without air conditioning difficult. High humidity adds to the discomfort, averaging around 71% over the three months.

Summer is also wet and sunny at once: Osaka recorded about **565mm (22.3 inches)** of rain over the period, much of it during June's rainy season, alongside roughly 942 hours of sunshine.

For visitors, this means peak summer in Osaka calls for light clothing, sun protection, and regular hydration, with indoor attractions and early-morning sightseeing the smart way to dodge the worst midday heat. Late June, before the most intense heat sets in, tends to be the most comfortable window.

Question 2

Which season is the wettest in Osaka?

Accepted Answer

Summer is the wettest season in Osaka, with the meteorological summer of 2025 (June 1 to August 31) delivering roughly 566 mm (22.3 in) of rain — more than any other season that year.

The heaviest downpours arrived early in the season. June 2025 alone recorded about 297 mm (11.7 in) of precipitation, making it the single wettest month of the year in Osaka. This reflects the East Asian rainy season, when warm, moisture-laden air settles over the region before the peak of summer heat.

For comparison, the other 2025 seasons in Osaka were noticeably drier:

- **Autumn (Sep–Nov 2025):** about 455 mm (17.9 in)
- **Spring (Mar–May 2025):** about 407 mm (16.0 in)
- **Winter (Jan–Feb 2025):** only about 60 mm (2.4 in)

Across all of 2025, Osaka received roughly 1,543 mm (60.8 in) of rain, so summer accounted for well over a third of the annual total on its own.

If you are planning a trip, expect the highest chance of rain from June through September, when humidity also stays high at around 70%. Travelers wanting drier conditions should target late autumn or winter, when monthly rainfall in Osaka drops sharply. Packing a compact umbrella and breathable rain gear is wise for any summer visit to the city.

Question 3

What is the sunniest time of year in Osaka?

Accepted Answer

The sunniest time of year in Osaka is summer, with **July** standing out as the brightest month of 2025 at 357.3 hours of sunshine—roughly 11.5 hours of sun per day.

Across 2025, Osaka recorded a generous 2,912 hours of sunshine, averaging about 8.0 hours per day over the year. The summer months of June, July and August (meteorological summer, June 1 to August 31) delivered the strongest stretch, totalling 941.8 hours and averaging 313.9 hours per month. The three sunniest months were:

- **July:** 357.3 hours
- **August:** 327.4 hours
- **September:** 272.8 hours

By contrast, the dimmest month was February with just 173.0 hours, or about 6.2 hours of sun per day. Late spring also shines, with April (256.8 hours) and May (263.1 hours) offering plenty of bright days before the summer heat peaks.

Keep in mind that Osaka's sunniest months are also its hottest: July averaged 29.8°C (85.6°F) in 2025, so peak sunshine comes with high temperatures and humidity. If you want bright skies with milder conditions, April and May are an excellent window, balancing long sunny days with comfortable temperatures. For the absolute maximum daylight and clear skies, plan your visit to Osaka for July and August—just pack sun protection and stay hydrated.

Question 4

What is the annual temperature range in Osaka?

Accepted Answer

Osaka has a wide annual temperature range, swinging from a cool February to a hot, humid August across 2025. Based on full-year 2025 data, the city's average monthly temperature climbed by about 26.2°C (47.2°F) between its coldest and warmest months.

February was the coldest month of 2025, with an average temperature of just 4.0°C (39.2°F), while August was the warmest at 30.2°C (86.4°F). This makes Osaka a true four-season city, where winter and summer feel like entirely different climates.

The extremes were even more dramatic. Looking at the daily figures behind the monthly aggregates, Osaka's temperatures in 2025 spanned roughly 41.8°C (75.2°F) in total:

- Lowest reading: -2.7°C (27.1°F), recorded in February 2025
- Highest reading: 39.1°C (102.4°F), recorded in July 2025
- Annual mean temperature: 16.9°C (62.4°F)

For visitors, this big spread means packing depends heavily on timing. Winter trips to Osaka call for warm layers and a coat, while midsummer demands lightweight clothing, sun protection, and plenty of hydration to cope with high heat and humidity. The mild shoulder months of spring and autumn sit comfortably in between, offering the most temperate conditions of the year.

Question 5

How much total rainfall does Osaka get per year?

Accepted Answer

Osaka received a total of about **1,543 mm (60.7 inches)** of rainfall across the full 2025 calendar year (January 1 to December 31), making it a notably wet city by global standards.

Rainfall was spread unevenly through 2025, averaging roughly 129 mm (5.1 inches) per month. The clear peak came in early summer: June 2025 was the wettest month with 296.8 mm (11.7 inches), driven by Japan's seasonal rainy front. The driest month was January 2025, with just 26.8 mm (1.1 inches).

Most of Osaka's annual rain falls in a concentrated window. From May through September 2025, the city recorded about 1,010 mm of precipitation — roughly 65% of the entire year's total. By meteorological season, summer (June–August 2025) led with 565.6 mm (22.3 inches), followed by autumn (September–November 2025) at 455 mm (17.9 inches) and spring (March–May 2025) at 406.7 mm (16 inches).

For visitors, this pattern has practical implications. If you want to avoid the heaviest rain in Osaka, the late autumn and winter months are by far the driest, with November and December 2025 each seeing under 56 mm. Travelers heading to Osaka between June and September should pack an umbrella and plan for frequent wet days, while the cooler months offer much more reliable, drier conditions for sightseeing.

Sangen’ya-nishi

Osaka

FAQ

How hot does Osaka get in summer?

Which season is the wettest in Osaka?

What is the sunniest time of year in Osaka?

What is the annual temperature range in Osaka?

How much total rainfall does Osaka get per year?