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Gassan ski resort
Tier E — Deep timing play — aim late winter

📷 Gassan

Asia

Gassan

Off-season

Conditions data updated Sat, Aug 29, 10:02 AM UTC · informational only

Off-season

Weather data is still collected for informational purposes.

Last Snowfall

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Past 24 Hours

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Past 48 Hours

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Past 10 Days

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14-Day Forecast

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Snow Depth

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Updated: Aug 29, 10:02 AM•Weather at base: 1235m

Overview

Gassan is a ski resort in Asia, Japan, currently closed for the season. Conditions last updated 2026-08-29 10:02 UTC.

Resort Guide

Gassan Ski Resort is located in Yamagata Prefecture, Japan, on the slopes of Mount Gassan. Known for its unique spring and summer ski season due to heavy winter snowfall, the resort typically operates from April to July. Gassan offers a relaxed atmosphere with natural, ungroomed slopes, catering primarily to intermediate and advanced skiers seeking a distinctive late-season experience. Key amenities include rental services and a simple base lodge, with the resort standing out for its deep snowpack and scenic mountain views.

Resort Info

Summit1670m
Base1235m
Vertical435m
Lifts3
Runs4
Skiable Area444.8 acres
Average snowfall1181 inches / 3000 cm
CountryJapan
Visit Resort Website →Follow on Instagram →View Trail Map →

Ski passes

No ski pass found

Access tiers change by season — confirm benefits on the pass operator's site.

Top Après Ski

Unable to determine top apres ski place for this resort.

Snow Summary

1670mECMWF Model

Updated Aug 29, 2026 at 10:02 AM

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24h
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Past 10d
14-Day Forecast
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Prev10d
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Now29
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S30
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M31
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T1
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Today
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Snowfall Forecast Maps

Japan (Tohoku & Niigata) region

Current Conditions

Reported Sat, Aug 29, 10:02 AM UTC

Base

1235m

Temp

12.5°C

Wind

7.2km/h

Snow Depth

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14-Day Forecast

0cm

Mid-Mountain

1453m

Temp

--°C

Wind

8km/h

Snow Depth

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14-Day Forecast

0cm

Summit

1670m

Temp

9.7°C

Wind

7.2km/h

Snow Depth

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14-Day Forecast

0cm

El Niño Outlook · Winter 2026-27

Gassan El Niño rank & forecast

Gassan ranks #402 of 488 SnowSure resorts — Tier E, −14% in strong El Niño winters.

Tier E — Deep timing play — aim late winter: Strong El Niño winters ran clearly below this resort’s own baseline (≤ −8%). Still skiable — schedule late season; one storm cycle can beat the climatology.

#402 of 488Tier E — Deep timing play — aim late winter

Strong-event signal: −14% vs this resort's 30-yr avg

In the three strongest El Niño winters on record ('97-98, '15-16, '23-24), Gassan averaged -14% versus its own 30-year snowfall baseline. Historically this is a timing play rather than a reason to stay home: aim for late winter (February–March) in winter 2026-27. Analog winters: '97-98 -35%, '15-16 -34%, '23-24 +26%. A pattern, not a promise.

'97-98 −35%'15-16 −34%'23-24 +26%

Signal = average snowfall in the three strongest El Niño winters since 1996 ('97-98, '15-16, '23-24) vs this resort's own 30-year ERA5 baseline. n=3 — a lean, not a law. Updated monthly against measured snowfall Dec–Mar.

Full El Niño report →

Live Conditions

Gassan Webcam

All Webcams

Gassan Kanko Kaihatsu Co.

1 webcam • Click to expand

Local Reports

0 reports
SnowSure™ Forecast Range

Daily Snowfall Forecast by Model

Black line = verified SnowSure™ blend (not a simple average). Weights update weekly from measured snowfall at SNOTEL stations and resort reports.

SnowSure™ blend — verified model weighting

The black line is not a simple average. For Gassan (japan), we combine seven global weather models using weights learned from daily forecast verification — comparing each model's prediction to measured snowfall (SNOTEL, resort reports, ERA5).

  • 1.Horizon buckets: days 1–3, 4–7, and 8–14 each get separate weights — short-range skill differs from long-range.
  • 2.Regional calibration: weights come from verified error in this geography (Rockies, Alps, Japan, etc.), recalculated weekly.
  • 3.Ground truth only: we never grade a forecast against another model — only against measured snow.

Building verification history for this resort.

How we verify forecasts →

Hourly Forecast Detail

AM / PM / Night breakdown with wind and freezing level

NWP models refresh up to 4× daily · Last synced Aug 29, 10:02 AM

Hourly Forecast Detail
 
Today
11 / 92.7mm
Sun, Aug 30
13 / 1035.4mm
Mon, Aug 31
16 / 101.5mm
Tue, Sep 1
17 / 1039.3mm
Wed, Sep 2
19 / 138.9mm
Thu, Sep 3
15 / 1028mm
PeriodAMPMNightAMPMNightAMPMNightAMPMNightAMPMNightAMPMNight
Snow (cm)000000000000000000
Precip (mm)1.51.203.913.118.4001.526.311.51.50.95.52.53.317.37.4
Temp (°C)111110111311131511131613171714141312
Wind (km/h)2558658106876894776
Gusts (km/h)121718242719223018293121172016223224

14-Day Snow Forecast by Model

Summit elevation (1670m)

ECMWF
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GFS
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GEM
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JMA
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ICON
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Météo-Fr
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SnowSure™
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10-Day Forecast

Today

29

🌧️

11.4°

9.1°

8 km/h

Sun

30

🌧️

13.2°

10°

8 km/h

Mon

31

🌧️

15.5°

10.4°

10 km/h

Tue

1

🌦️

17.2°

10.4°

8 km/h

Wed

2

🌦️

18.9°

13.1°

12 km/h

Thu

3

🌧️

15.3°

9.9°

9 km/h

Fri

4

🌧️

12.8°

7.2°

12 km/h

Sat

5

🌧️

12.5°

6.9°

7 km/h

Sun

6

☁️

12.6°

6.2°

11 km/h

Mon

7

☁️

13°

6.2°

13 km/h

Summit elevation (1670m) • ECMWF model

Avalanche

No bulletin for this mountain

No official warning service is mapped for this resort’s country yet (v1 covers the United States, Canada and Switzerland). A bulletin may still be published locally.

SnowSure relays the official avalanche bulletin and does not issue avalanche forecasts. Read the full bulletin at the issuer’s link and make your own terrain decisions. Not a substitute for avalanche education, equipment, or local knowledge.

Season vs Historic

Updated Sat, Aug 29, 10:02 AM UTC

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Season Total

This Season to Date

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vs 5-Year Avg

Off-season · 710cm full-season avg

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vs 30-Year Avg

Off-season · 570cm full-season avg

710cm

5-Yr Avg by Now

The last completed season totaled ~724.2 cm. That's near the 5-year average (710 cm). Versus the 30-year baseline: 27% above the 30-year average (570 cm).

Gassan Snow History

Average annual snowfall is 595cm with an average of 118 snowfall days per season. The table below shows monthly averages across 30 seasons of archive data (modeled snowpack at mid-elevation).

Average monthly snowfall history
MonthAvg SnowfallSnowfall DaysAvg Base DepthMax Base DepthBiggest Snowfall
November40.3cm10 days4cm17cm10.2cm
December150.9cm25 days44cm86cm16.3cm
January178.7cm29 days124cm160cm18cm
February116.9cm25 days167cm187cm13.6cm
March83.9cm21 days170cm191cm13.2cm
April24cm8 days113cm162cm8.6cm
May0.3cm0 days13cm61cm0.7cm

Source: SnowSure archive · Open-Meteo ERA5 reanalysis at mid-elevation. Depth is modeled, not resort-reported.

Season at a Glance

Next season(2025-26)

Opens Apr 10, 2026

Multi-season averages will appear once SnowSure has tracked more than one full season.

ENSO seasonal analog

History · not a forecast

In 10 past El Niño winters at Gassan, ERA5 season snowfall median was 508 cm (200 in), about 5% below this resort’s long-term median. This is a historical analog from reanalysis — not a prediction of this winter’s storm track.

Prevailing ONI

El Niño

MJJ 2026 · ANOM +1.39°C

Analog season median

508 cm

10 El Niño winters · 5% below median

All-season median

537 cm

Across 30 ERA5 seasons (2026-27)

PhaseSeasonsMedianp25–p75Recent analogs
El Niñocurrent10508 cm419 cm – 666 cm2023, 2019, 2018, 2015, 2014, 2009
La Niña12561 cm510 cm – 706 cm2022, 2021, 2020, 2017, 2011, 2010
ENSO-neutral8550 cm486 cm – 771 cm2025, 2024, 2016, 2013, 2012, 2003

Season snowfall from Open-Meteo ERA5 reanalysis (~9 km). ENSO phase from NOAA CPC Oceanic Niño Index. Relative phase differences are more trustworthy than absolute cm totals. Source: NOAA CPC Oceanic Niño Index + Open-Meteo ERA5 via SnowSure season archive.

Best Months to Visit

January

Peak Powder

February

Peak Powder

March

Good

December

Good

Note: Based on typical powder season patterns for this region.

Back to All Destinations

Frequently asked questions about Gassan

Where is Gassan?
Gassan is a ski resort in Japan.
How high is Gassan?
Gassan runs from a base elevation of 1,235 m (4,052 ft) to a summit of 1,670 m (5,479 ft), giving a vertical drop of 435 m (1,427 ft).
How big is Gassan?
Gassan has 445 acres (180 hectares) of skiable terrain, 4 marked runs and 3 lifts.
Which ski pass covers Gassan?
Gassan is on the No ski pass found. Access terms such as blackout dates and day limits vary by pass tier, so check the pass operator for the current season.
How much snow does Gassan get in a typical season?
Gassan averages 1181 inches / 3000 cm of snowfall in a typical season. Any individual season can run well above or below that.
How will El Niño affect Gassan in winter 2026-27?
El Niño Signal Rank: #402 of 488 SnowSure resorts · Tier E · strong-event signal -14% vs its own 30-yr average. In the three strongest El Niño winters on record ('97-98, '15-16, '23-24), Gassan averaged -14% versus its own 30-year snowfall baseline. Historically this is a timing play rather than a reason to stay home: aim for late winter (February–March) in winter 2026-27. Analog winters: '97-98 -35%, '15-16 -34%, '23-24 +26%. A pattern, not a promise.