How are weather forecasts divided? I looked into the detailed area divisions used for weather forecasts in the Tohoku region

We casually look at weather forecasts every day... but have you ever wondered, "Where exactly are the distinctions made between coastal areas, inland areas, eastern areas, and western areas?"

This time, we've taken a closer look at the "primary subdivision area" and "secondary subdivision area" used in weather forecasts

---

Weather forecast for the Tohoku region - primary subdivision area

weather forecasting"primary subdivision areas"refer to the regular subdivision of forecasts, divided based on meteorological characteristics, disaster characteristics, and geographical characteristics.

The primary subdivisions of the Tohoku region are as shown in the image below

The characteristics of each region are as follows:

• Aomori Prefecture is divided into three areas: "Tsugaru" on the Sea of ​​Japan side, "Sanpachi-Kamikita" in the southern part of the Pacific side, and "Shimokita" in the northern part of the Pacific side . While the Tsugaru region experiences heavy snowfall in winter, the Pacific side receives relatively less snow.
• Iwate Prefecture : Divided into "inland" and "coastal" areas by the Kitakami Highlands , with the coastal area further divided into "northern coastal" and "southern coastal ." The Tono area, located in the basin of the Kitakami Highlands, experiences greater temperature fluctuations than other inland regions
• Akita Prefecture : Divided simply into "coastal" and "inland" areas by the Dewa Mountains , with no north-south division. It has a Sea of ​​Japan climate, with heavy snowfall even along the coast, and even more snowfall recorded in the inland areas. It has the shortest winter sunshine hours in the country.
• Miyagi Prefecture : Divided into two areas, "eastern" and "western," based on the Tohoku Expressway . The western area, which is inland, experiences heavy snowfall in winter
• Yamagata Prefecture is divided into four regions: "Shonai" in the Shonai Plain , "Mogami" centered around the Shinjo Basin , " Murayama" centered around the Yamagata Basin, and "Okitama" encompassing the Yonezawa Basin and Nagai Basin . Similar to Akita, it has a climate on the Sea of ​​Japan side with heavy snowfall, but the inland areas experience high temperatures in the summer.
• Fukushima Prefecture: The prefecture is divided into three areas because the Ou Mountains run vertically between "Aizu" and "Nakadori," and the Abukuma Highlands run vertically between "Nakadori" and "Hamadori." The names are derived from past main roads; "Nakadori" is named after the Nakasendo road, and "Hamadori" is named after the Hamakaido road

---

Secondary subdivisions by prefecture in the Tohoku region

A "secondary subdivision area"is a classification used for issuing weather warnings and advisories, and while there are some exceptions, it is basically divided based on municipalities.

The primary subdivision area is further subdivided

In each image, the difference in color represents the "primary subdivision area , " and the area separated by the black line represents the "secondary subdivision area."

Secondary subdivision areas of Aomori Prefecture

In Aomori Prefecture, the primary subdivision of Tsugaru is divided into four areas: "East Aomori Tsugaru," "North Go Tsugaru," "Central and Southern Tsugaru," and "West Tsugaru." The Sanpachi Kamikita area is divided into two areas: "Kamikita" and "Sanpachi ." The "Shimokita" region has the same primary and secondary subdivisions, resulting in a total of seven areas

Secondary subdivision area of ​​Iwate Prefecture

Iwate Prefecture, with its vast inland area, is divided into six primary subdivision areas : "Ninohe Region," "Morioka Region," "Hanakita Region," "Tono Region," "Oshu Kanegasaki Region," and "Ryoban Region." The northern coast is divided into two regions : "Kuji Region" and "Miyako Region," and the southern coast is divided into two regions: "Kamaishi Region" and "Ofunato Region ."

In stark contrast to the primary subdivision zones, the secondary subdivision zones are divided into 10 zones , representing a significant degree of subdivision

Secondary subdivision areas of Akita Prefecture

Akita Prefecture is further divided into three secondary subdivisions: the coastal area is divided into the "Noshiro-Yamamoto region," the "Akita Central region," and the "Yurihonjo region," and the inland area is divided into three regions: the "Kita-Akita-Kazuno region," the "Senboku-Hiraka region," and the "Yuzawa-Ogachi region ."

The initial subdivision area is divided into three equal parts: northern, central, and southern, making it easy to understand. This results in a total of six secondary subdivision areas

Secondary subdivision areas of Miyagi Prefecture

In contrast to the simple primary subdivisions in Miyagi Prefecture, the secondary subdivisions are divided into much more detailed areas

First, the eastern part is divided into six areas: "Kesennuma region," "Tome/Eastern Kurihara," "Eastern Osaki," "Ishinomaki region," "Eastern Sendai," and "Eastern Sennan ." The western part is divided into four areas: "Western Kurihara," "Western Osaki," "Western Sendai," and "Western Sennan," resulting in a total of 10 subdivided areas

Secondary subdivision area of ​​Yamagata Prefecture

Yamagata Prefecture is divided into eight zones: Shonai is divided into two zones, "Northern Shonai" and "Southern Shonai"; Mogami is divided into one zone, " Mogami," similar to the temporary subdivision zone; Murayama is divided into three zones, "Northern Murayama," "Western Murayama," and "Southeastern Murayama"; and Okitama is divided into two zones , "Western Okitama" and "Southeastern Okitama."

Secondary subdivision areas of Fukushima Prefecture

Like Akita Prefecture, Fukushima Prefecture has a simple system where its temporary subdivisions are divided into three areas: northern, central, and southern

First, Aizu is subdivided into "Northern Aizu," "Central Aizu," and " Southern Aizu," Nakadori into "Northern Nakadori," "Central Nakadori ," and "Southern Nakadori," and Hamadori into "Northern Hamadori," "Central Hamadori," and "Southern Hamadori," for a total of nine areas

Incidentally, the southern part of the Hamadori region consists of only one city, Iwaki City

---

summary

"primary subdivision area" and "secondary subdivision area"are merely criteria used by the Japan Meteorological Agency for various announcements; of course, some TV stations and programs may provide more detailed weather forecasts.

Furthermore , please note that the names and boundaries of these classifications may change over time, so the information in this article is current as of 2026 !

---