taknishikawa/analog-year-weather-maps

Analog Year Weather Maps

ERA5 reanalysis-based tool to find historical years with similar atmospheric patterns ("analog years") and generate composite weather maps.

Features

• —Composite maps for any date range using ERA5 / ERA5T data (~5-day lag)
• —Analog year finder — ranks past years by area-weighted pattern correlation
• —Variables: Z500, SLP, T2m, T850, T500, U200, U500, precipitation, ω500, SST, 10 m wind speed, OLR
• —Regions: Northern Hemisphere, Global, North Pacific, North Atlantic, Asia/Japan, and more
• —Anomaly and standardized anomaly maps (selectable climatology period)
• —Wind vector overlay for 10 m wind speed maps

Quick Start

1. Clone

git clone https://github.com/WeatherNote/public.git
cd public

2. Install dependencies

Requires Python 3.10+. Using a virtual environment is recommended.

pip install -r requirements.txt

Note (macOS/Linux): If cartopy fails to install via pip, use conda: ``bash conda install -c conda-forge cartopy pip install -r requirements.txt ``

3. Set up CDS API credentials

Register at https://cds.climate.copernicus.eu/ and obtain your API key.

Create ~/.cdsapirc:

url: https://cds.climate.copernicus.eu/api
key: <your-api-key>

Or copy the example file:

cp .cdsapirc.example ~/.cdsapirc
# then edit ~/.cdsapirc and fill in your key

4. Run

python main.py

Open http://localhost:8000 in your browser.

Notes

• —ERA5 data is cached in ./cache/ after the first download.
• —First-time downloads can take several minutes depending on the date range and variable.
• —Data availability: ERA5 covers 1940–present with ~5-day lag for the most recent period (ERA5T).

Data Source

ERA5 global reanalysis — Copernicus Climate Change Service (C3S)