Wind Direction on the Shimanami Kaido: A Tailwind Guide for Cyclists

Worried about headwinds on the Shimanami Kaido? Learn about typical wind directions, when strong westerly winds occur, and why starting from Imabari gives you the best chance of a tailwind.

Where is the Shimanami Kaido?

The “Shimanami Kaido” is a route connecting Onomichi City in Hiroshima Prefecture and Imabari City in Ehime Prefecture in western Japan. The islands floating between Honshu and Shikoku are linked by bridges, creating a route that cyclists and pedestrians can freely cross. Because of this unique setup, it is widely known as one of the world’s most famous cycling routes.

Along the route, you will find plenty of bicycle rental services and accommodations that welcome cycling travelers. Many rental bikes can be returned at a different terminal from where you started, making it easy to enjoy a one-way cycling trip—from Imabari to Onomichi, or from Onomichi to Imabari. This flexibility, combined with well-developed facilities for cyclists, is one of the reasons why the Shimanami Kaido is suitable for a wide range of travelers, from experienced cyclists to complete beginners.

The Shimanami Kaido can be reached from many parts of Japan by Shinkansen, limited express trains, or highway buses. To reach Imabari City on the Shikoku side, the most common route is to transfer to a limited express train at Okayama Station. To reach Onomichi City on the Honshu side, you can take the Sanyo Shinkansen to Shin-Onomichi Station or Fukuyama Station and then transfer to a local train.

One of the biggest attractions of cycling the Shimanami Kaido is being able to travel at your own pace through the calm seas of the Seto Inland Sea and the peaceful scenery of its islands. Crossing several large bridges by bicycle—bridges that you would not normally experience in this way—is something truly unique to the Shimanami Kaido.

Should you start from Imabari or Onomichi?

If you want to cycle the entire Shimanami Kaido, one of the first questions you may face is “Should I start from Imabari or from Onomichi?”. Looking at travel blogs and social media posts by international visitors, many people seem to choose Onomichi as their starting point, partly because it is relatively easy to access.

On the other hand, many guidebooks and information sources—including the cycling guidebook Shimanami Toso Book—mention that “starting from Imabari often gives you a better chance of enjoying a tailwind.” On this page, I took a closer look at the “wind” on the Shimanami Kaido, including the typical patterns and the risk of encountering headwinds.

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Wind conditions on the Shimanami Kaido

Typical wind patterns in the Seto Inland Sea

As the name “Setouchi Shimanami Kaido” suggests, this route crosses the Seto Inland Sea. On a map, it is located on the western side of the Seto Inland Sea. The Seto Inland Sea is an inland sea situated between two mountain ranges: the Chugoku Mountains on the Honshu side and the Shikoku Mountains on the Shikoku side. Because it is surrounded by land on all sides, the geography is sometimes compared to the Mediterranean Sea. Due to this unique landscape, the region is known in Japanese meteorology for a distinctive climate called the “Seto Inland Sea climate.”

Winds blowing from the Pacific Ocean or the Sea of Japan are often blocked by these mountain ranges. As a result, the wind tends to flow around the mountains and pass through natural corridors such as the Kanmon Strait (between Honshu and Kyushu), the Bungo Channel (between Shikoku and Kyushu), and the Kii Channel (between Shikoku and Honshu). Because of this, winds in the Seto Inland Sea region tend to blow from the east or from the west.

Wind characteristics of the Shimanami Kaido

First, let’s check the relative positions of the two ends of the Shimanami Kaido: Imabari and Onomichi. If you look at a map, you’ll see that Imabari on the Shikoku side is located slightly farther west than Onomichi. In simple terms, a westerly wind tends to create a tailwind when starting from Imabari, while an easterly wind tends to favor starting from Onomichi.

Wind Speed and How It Feels While Cycling

Knowing how different wind speeds typically feel while cycling can help when planning your ride. Based on personal experience, a wind speed of around 3 m/s is generally not a problem and you can ride comfortably. At around 5 m/s, you may start to feel some resistance, and headwinds in particular can make you tire more easily. A headwind of about 8 m/s can feel quite strong and will noticeably increase fatigue. When wind speeds exceed 10 m/s, extra caution is recommended—especially for beginners who are not used to cycling in windy conditions.

Wind Speed	How It Feels
3 m/s	Little to no problem
5 m/s	Slightly difficult
8 m/s	Headwinds feel quite tough
10 m/s	Beginners should take extra care

The most common wind direction: easterly

The website of the JMA (Japan Meteorological Agency) provides access to historical weather data. By looking at the AMeDAS observation data for Omishima, Ikuchijima, and Imabari, you can see detailed weather trends for the Shimanami Kaido area by year, month, and day. Since this dataset also includes information on “wind direction and wind speed,” I referred to these records for this article.

Omishima — September 2020 (Daily values)

Day	Avg. Wind Speed (m/s)	Max. Wind Speed (m/s)	Max. Wind Direction	Max. Gust Speed (m/s)	Max. Gust Direction	Dominant Direction
1	1.5	3.5	NE	6.8	NNE	NE
2	2.9	5.8	NE	11.3	NE	ENE
3	3.0	6.6	WSW	13.0	WSW	WSW
4	1.2	3.3	SW	6.1	S	NE
5	1.5	3.3	ENE	7.0	NNE	NE
6	3.3	6.5	NE	13.6	NE	NE
7	4.2	7.1	SW	14.0	SW	WSW
8	2.5	6.0	WSW	9.4	WSW	WSW
9	1.3	3.7	SW	9.7	WSW	NE
10	1.6	3.5	NE	6.3	NNE	NE
11	1.7	3.6	ENE	6.5	NE	NE
12	1.3	3.6	ENE	6.8	ENE	ENE
13	1.5	3.4	WSW	6.4	SSW	SW
14	1.5	2.9	WSW	5.4	NNE	NE
15	1.8	3.8	NE	6.6	NNE	NE
16	1.2	2.9	NE	4.7	NE	NE
17	1.1	2.8	SW	4.8	WSW	NE
18	2.2	5.5	WSW	11.9	WSW	WSW
19	1.4	3.1	WSW	5.0	WSW	NE
20	1.6	3.2	WSW	5.8	NW	NE
21	1.9	3.9	NE	7.1	NE	NE
22	1.8	4.0	ENE	7.6	ENE	NE
23	1.4	4.5	NE	8.0	NE	NE
24	1.0	3.1	ENE	5.0	ENE	NE
25	1.4	6.0	ENE	9.8	ENE	NE
26	1.2	3.1	SW	5.1	WSW	NE
27	1.3	3.2	ENE	6.4	ENE	NE
28	1.9	4.3	NE	8.3	ENE	NE
29	1.6	3.3	ENE	5.0	ENE	NE
30	1.0	2.8	ENE	5.1	ENE	ENE
Source: JMA, Past Weather Data | Omishima, Ehime Prefecture — September 2020 (Daily values)

First, I looked at the “most frequent wind direction,” meaning the direction the wind blows most often. The exact pattern varies slightly depending on the season and the specific AMeDAS observation point, but in this area the most common winds tend to come from the east—such as northeast, east, or north-northeast. Looking at the data for Omishima during August to October, when many people cycle the Shimanami Kaido, the most frequent wind direction is overwhelmingly “northeast.”

Of course, the exact wind pattern depends on the day’s atmospheric pressure systems. However, it seems common for winds to flow in from relatively low-lying areas around the Kii Channel and the Kansai region, then pass through the Seto Inland Sea from east to west. At first glance, then, it might seem that starting from Onomichi and heading toward Imabari would give you a tailwind more often, making the ride feel easier.

Strongest winds often come from the west

However, if we look at the “maximum wind direction,” meaning the direction of the wind when the strongest gusts occur, a different pattern appears. At all three observation points—Omishima, Ikuchijima, and Imabari—the monthly records show that the maximum wind direction is overwhelmingly “west-southwest,” in other words winds from the west. This suggests that stronger winds often occur when air flows through the Bungo Channel, the sea passage between Kyushu and Shikoku.

Omishima — 2020 (Monthly values)

Month	Avg. Wind Speed (m/s)	Max. Wind Speed (m/s)	Max. Wind Direction	Max. Gust Speed (m/s)	Max. Gust Direction
Jan	2.3	13.8	WSW	21.6	W
Feb	2.4	11.6	WSW	18.7	WSW
Mar	2.3	11.0	WSW	17.4	WSW
Apr	2.4	7.8	WSW	14.7	SW
May	1.9	7.8	WSW	15.1	WSW
Jun	1.8	7.1	WSW	13.7	WSW
Jul	1.5	6.5	SW	14.9	SW
Aug	1.5	5.1	NE	9.2	WSW
Sep	1.8	7.1	SW	14.0	SW
Oct	1.8	6.3	WSW	12.4	NE
Nov	1.8	7.5	WSW	12.4	SW
Dec	2.4	9.8	WSW	18.4	WSW
Source: JMA, Past Weather Data | Omishima, Ehime Prefecture — 2020 (Monthly values)

Easterly winds may be less likely to become very strong because the path the wind travels across the Seto Inland Sea is longer and there are many islands along the way. In contrast, when westerly winds blow, the distance from the Pacific Ocean is shorter and there are fewer obstacles, which may allow the wind to become stronger.

Looking at the meteorological data, on days when the wind tends to become stronger, starting from Imabari and heading toward Onomichi is more likely to give you a helpful tailwind. Conversely, if you start from Onomichi on such a day, you may encounter a strong headwind, which could drain your energy and take more time than you expected.

Starting from Imabari is often recommended

To summarize the points above, the wind around the Shimanami Kaido seems to follow a pattern: “most days have relatively gentle winds from the east, but occasionally strong winds blow from the west.” Considering that strong winds have a greater impact on cycling, starting from Imabari and heading toward Onomichi may reduce the risk of facing a strong headwind.

This also explains why so many guides and travel resources recommend Imabari as the better starting point. The idea is supported by actual meteorological observation data. From my own experience cycling the Shimanami Kaido many times, I also feel that the toughest headwinds tend to occur when riding toward Imabari.

If you rent a bicycle in Imabari, the public rental system (Shimanami Rental Cycle) has two locations: the “Imabari Station Cycling Terminal” and “Sunrise Itoyama.” For cross bikes and city bikes, you can return the bicycle not only in Onomichi but also at other rental cycle terminals along the Shimanami Kaido route.

Rental Cycle Terminal	Imabari Station Rental Cycle	Imabari Itoyama Rental Cycle
Facility	Imabari Station i.i.imabari! Cycle Station	Sunrise Itoyama
Address	2-773-8 Kitahorai-cho, Imabari City	2-8-1 Sunaba-cho, Imabari City
Opening Hours	8:00–19:00 (until 18:00 in winter)	8:00–19:00 (until 18:00 in winter)
Bike Types Available	Cross bikes, city bikes, electric-assist bikes, e-bikes	Cross bikes, city bikes, electric-assist bikes, e-bikes, tandem bikes, children’s bikes, etc.
Access	Located directly in front of Imabari Station, less than a 1-minute walk. The Blue Line cycling route also starts right nearby.	Public transportation access is somewhat limited. Local buses run infrequently, so please plan accordingly.

*[Winter season] From December to February, some terminals have shorter opening hours.

Seasonal differences in wind

The information above explains the general wind trends for the entire Shimanami Kaido area, but at ground level—where you actually cycle—winds are strongly influenced by the local terrain. The Shimanami area consists of a complex layout of islands of various sizes. Winds can swirl around islands or descend from the mountains in the center of larger islands, so the conditions vary significantly depending on your location.

According to the Matsuyama Local Meteorological Observatory, summer winds are largely influenced by sea and land breezes, which often blow perpendicular to the coastline, though overall winds tend to be weak. In contrast, winter brings a “west high, east low” pressure pattern (typical of Japan’s winter), which strengthens seasonal winds, often causing stronger west to northwest winds. You can read more about the benefits and precautions for cycling the Shimanami Kaido in winter on this page.

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Checking wind forecasts

Check wind forecasts alongside weather forecasts

Once your cycling dates on the Shimanami Kaido are set, one of the first things to check before your trip is the weather forecast. Most people check whether it will be sunny or if there is a chance of rain. However, for cycling trips, it’s also recommended to check the wind forecast. This is a detail that novice cyclists often overlook, but wind direction and strength can greatly affect both the comfort of your ride and the time it takes to complete it.

Depending on your accommodations and transport, it might be difficult to change your starting point at the last minute. Still, by checking the wind forecast, you can plan alternative options such as taking a ferry for a shortcut or adjusting your route. If strong headwinds are expected, it’s wise to anticipate a longer travel time and build extra buffer into your schedule for a safer, more enjoyable ride.

Wind forecasts made easy with “Windy”

For checking wind forecasts, the web service “Windy.com” (also available as a smartphone app) is extremely useful. It provides highly accurate wind direction forecasts using meteorological prediction models, and you can access this for free. Around the Shimanami Kaido, the wind patterns are shown in visually intuitive graphics, making it perfect for pre-trip planning. The service supports both Japanese and English, so it’s easy for travelers from overseas to use as well.

The islands along the Shimanami Kaido have complex terrain, so localized winds that swirl around islands may cause the actual experience to differ from the forecast. While the free version may not fully reflect such fine-scale terrain effects, it is still very helpful for understanding the overall wind trends.

Closures due to strong winds

The dedicated cycling and pedestrian paths on the bridges along the Shimanami Kaido may be closed if strong winds are expected. In all previous cases, the closures were due to strong winds. According to the Honshu-Shikoku Expressway website, all bridge traffic—including cars—is closed when the 10-minute average wind speed is forecast to exceed 25 m/s. When winds exceed 15 m/s, two-wheeled vehicles are restricted from crossing.

For cycling and pedestrian paths specifically, the exact wind speed threshold for closure has not been publicly announced. It is likely similar to the restrictions for two-wheeled vehicles on expressways, but there are cases where only the cycling/pedestrian paths (including mopeds) are restricted. If wind speed is the determining factor, the threshold may be stricter than the 15 m/s used for two-wheeled vehicles.

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On this page, I explored the winds along the Shimanami Kaido, including typical wind directions, wind strength, and considerations for choosing between starting at Imabari or Onomichi. For more detailed cycling information suitable for beginners to experienced riders, please check the following page—it’s a helpful resource for planning your ride.