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#!/usr/bin/env python3
"""weather -- one fetcher for the whole fleet.
Hits Open-Meteo (model=best_match, so NOAA blend in the US, ECMWF/ICON abroad),
normalises the reading, caches the last good value, and prints it. Every app
(waybar, clock-panel, an Emacs svg.el panel) shells out to this and renders the
JSON -- nobody re-implements the API call, the code mapping, or the cache.
Stdlib only: no pip, no venv. Runs as a bare executable.
Contract (--format json):
{
"temp_f": 82, "feels_f": 92,
"condition": "clear", # clear|partly|cloud|fog|rain|snow|storm
"wmo_code": 0,
"windy": false, # wind_mph >= threshold (default 15)
"wind_mph": 6, "wind_dir": "WNW", "wind_deg": 293,
"location": "New Orleans",
"observed": "2026-07-18T01:00", "stale": false
}
Location resolves in order: --lat/--lon, then $WEATHER_LAT/$WEATHER_LON, then
~/.config/weather/config.json, then `whereami` (with --geo). No coordinates are
baked in, so nothing personal ships in the repo -- each machine configures its
own.
"""
import argparse
import json
import os
import subprocess
import sys
import time
import urllib.error
import urllib.request
from pathlib import Path
API = "https://api.open-meteo.com/v1/forecast"
CONFIG = Path(os.environ.get("XDG_CONFIG_HOME", Path.home() / ".config")) / "weather" / "config.json"
CACHE = Path(os.environ.get("XDG_CACHE_HOME", Path.home() / ".cache")) / "weather" / "current.json"
DEFAULT_TTL = 900 # 15 min -- weather changes slowly; keep API calls rare
DEFAULT_WINDY = 15 # mph; Beaufort 4, where wind stops being ambient
# WMO weather-interpretation code -> our semantic condition.
# Ranges collapse to the seven condition glyphs; "windy" is derived from speed.
_WMO = {
0: "clear",
1: "partly", 2: "partly",
3: "cloud",
45: "fog", 48: "fog",
51: "rain", 53: "rain", 55: "rain", 56: "rain", 57: "rain",
61: "rain", 63: "rain", 65: "rain", 66: "rain", 67: "rain",
80: "rain", 81: "rain", 82: "rain",
71: "snow", 73: "snow", 75: "snow", 77: "snow", 85: "snow", 86: "snow",
95: "storm", 96: "storm", 99: "storm",
}
_CARDINALS = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE",
"S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"]
def condition_for(code):
return _WMO.get(int(code), "cloud") # unknown code -> cloud, the safe neutral
def cardinal(deg):
return _CARDINALS[int((deg % 360) / 22.5 + 0.5) % 16]
def resolve_location(args):
"""Return (lat, lon, name). Raise if nothing configured."""
if args.lat is not None and args.lon is not None:
return args.lat, args.lon, args.location
env_lat, env_lon = os.environ.get("WEATHER_LAT"), os.environ.get("WEATHER_LON")
if env_lat and env_lon:
return float(env_lat), float(env_lon), args.location or os.environ.get("WEATHER_NAME")
if CONFIG.exists():
cfg = json.loads(CONFIG.read_text())
if args.geo or cfg.get("use_geo"):
geo = _whereami()
if geo:
return geo[0], geo[1], args.location or cfg.get("name")
if "lat" in cfg and "lon" in cfg:
return cfg["lat"], cfg["lon"], args.location or cfg.get("name")
if args.geo:
geo = _whereami()
if geo:
return geo[0], geo[1], args.location
raise SystemExit(
"weather: no location. Pass --lat/--lon, set $WEATHER_LAT/$WEATHER_LON, "
f"write {CONFIG} (\"lat\"/\"lon\"[/\"name\"]), or use --geo on a machine "
"that travels."
)
def _whereami():
"""Best-effort coords from the `whereami` tool. Only meaningful where the
machine actually moves (velox); silently gives up otherwise."""
try:
out = subprocess.run(["whereami"], capture_output=True, text=True, timeout=20).stdout
except (OSError, subprocess.SubprocessError):
return None
for line in out.splitlines():
if "coords:" in line:
try:
nums = line.split("coords:")[1].split("(")[0]
lat, lon = (float(x) for x in nums.replace(",", " ").split()[:2])
return lat, lon
except (ValueError, IndexError):
return None
return None
def fetch(lat, lon, name, threshold):
params = (
f"?latitude={lat}&longitude={lon}"
"¤t=temperature_2m,apparent_temperature,weather_code,"
"wind_speed_10m,wind_direction_10m"
"&temperature_unit=fahrenheit&wind_speed_unit=mph"
"&models=best_match&timezone=auto"
)
req = urllib.request.Request(API + params, headers={"User-Agent": "weather-cli/1.0"})
with urllib.request.urlopen(req, timeout=15) as resp:
data = json.load(resp)
cur = data["current"]
mph = round(cur["wind_speed_10m"])
deg = cur["wind_direction_10m"]
return {
"temp_f": round(cur["temperature_2m"]),
"feels_f": round(cur["apparent_temperature"]),
"condition": condition_for(cur["weather_code"]),
"wmo_code": int(cur["weather_code"]),
"windy": mph >= threshold,
"wind_mph": mph,
"wind_dir": cardinal(deg),
"wind_deg": round(deg),
"location": name or f"{lat:.2f},{lon:.2f}",
"observed": cur["time"],
"stale": False,
}
def read_cache():
try:
blob = json.loads(CACHE.read_text())
return blob["fetched_at"], blob["reading"]
except (OSError, ValueError, KeyError):
return None, None
def write_cache(reading):
CACHE.parent.mkdir(parents=True, exist_ok=True)
CACHE.write_text(json.dumps({"fetched_at": int(time.time()), "reading": reading}))
def get_reading(args):
"""Cache-first, network-second, stale-cache-on-failure. One shared cache
means five widgets polling still hit the API at most once per TTL."""
fetched_at, cached = read_cache()
if cached and not args.no_cache and fetched_at and (time.time() - fetched_at) < args.ttl:
return cached
lat, lon, name = resolve_location(args)
try:
reading = fetch(lat, lon, name, args.windy_threshold)
write_cache(reading)
return reading
except (urllib.error.URLError, OSError, KeyError, ValueError) as e:
if cached: # never blank the bar: serve last good, flagged
cached["stale"] = True
return cached
raise SystemExit(f"weather: fetch failed and no cache to fall back on ({e})")
def render(reading, fmt):
if fmt == "json":
return json.dumps(reading)
if fmt == "plain":
wind = "windy" if reading["windy"] else reading["wind_dir"]
s = f"{reading['temp_f']}°F {reading['condition']}, wind {wind} {reading['wind_mph']}"
return s + (" (stale)" if reading["stale"] else "")
if fmt == "waybar":
# Data only; the caller's stylesheet picks the icon by `alt`/`class`.
wind = "windy" if reading["windy"] else f"{reading['wind_dir']} {reading['wind_mph']}"
return json.dumps({
"text": f"{reading['temp_f']}° {reading['wind_mph']}",
"alt": reading["condition"],
"class": (["stale"] if reading["stale"] else []) + [reading["condition"]]
+ (["windy"] if reading["windy"] else []),
"tooltip": f"{reading['location']}: {reading['temp_f']}°F "
f"(feels {reading['feels_f']}°), {reading['condition']}, "
f"wind {reading['wind_dir']} {reading['wind_mph']} mph"
+ (" [stale]" if reading["stale"] else ""),
})
raise SystemExit(f"weather: unknown format {fmt!r}")
def main(argv=None):
p = argparse.ArgumentParser(description="Normalised current weather from Open-Meteo.")
p.add_argument("--lat", type=float, help="latitude override")
p.add_argument("--lon", type=float, help="longitude override")
p.add_argument("--location", help="display name for the reading")
p.add_argument("--geo", action="store_true", help="geolocate via `whereami` (traveling machines)")
p.add_argument("--format", choices=["json", "plain", "waybar"], default="json")
p.add_argument("--windy-threshold", type=int, default=DEFAULT_WINDY, help="mph at which windy=true")
p.add_argument("--ttl", type=int, default=DEFAULT_TTL, help="cache seconds")
p.add_argument("--no-cache", action="store_true", help="force a fresh fetch")
args = p.parse_args(argv)
reading = get_reading(args)
# Derive windy from cached wind_mph so a changed threshold takes effect
# without waiting for the cache to expire.
reading["windy"] = reading["wind_mph"] >= args.windy_threshold
print(render(reading, args.format))
if __name__ == "__main__":
main()
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