SF Microclimates API

Real weather for 50 San Francisco neighborhoods. Free API. No key required.

🌐 Live API: microclimates.solofounders.com

Example website: view weather in all regions of San Francisco

Use with Claude Code, Clawdbot, or build into your apps.

Built by Solo Founders.

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Why This Exists

SF has the most dramatic microclimates of any US city.

Weather apps say "San Francisco: 58°F" — but that's useless. It can be 52°F and foggy in the Outer Sunset while it's 65°F and sunny in the Mission, just 3 miles apart.

This API aggregates 150+ outdoor sensors and groups them by neighborhood, so you get actual local temperatures — not some airport reading from SFO.

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Try It Instantly

curl https://microclimates.solofounders.com/sf-weather/mission

{
  "neighborhood": "mission",
  "name": "Mission District",
  "temp_f": 58,
  "humidity": 52,
  "pm2_5": 12.1,
  "aqi": 50,
  "aqi_category": "Good",
  "sensor_count": 8
}

No API key. No signup. Just use it.

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Add to Claude Code or Clawdbot

Copy and paste this into your skills folder:

# Create a new skill: sf-microclimates/SKILL.md


# SF Microclimates Skill

Get real-time SF neighborhood weather.

## Triggers
- "weather in [neighborhood]"
- "sf weather mission vs sunset"
- "is it foggy in the richmond?"

## Usage
curl https://microclimates.solofounders.com/sf-weather/marina

## Neighborhoods
mission, castro, marina, soma, haight, noe_valley,
outer_sunset, inner_sunset, outer_richmond, presidio,
north_beach, pacific_heights, potrero, twin_peaks...

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Use Cases

• AI agents — Give your agent real local weather context
• Home automation — Trigger based on your actual neighborhood temp
• Slack/Discord bots — Settle "is it foggy?" arguments
• Travel apps — Show tourists what to actually expect
• Personal dashboards — Finally, weather that matches your window

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Endpoints

Endpoint	Description
GET /sf-weather	All 50 neighborhoods
GET /sf-weather/:neighborhood	Single neighborhood
GET /neighborhoods	List all available

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50 Neighborhoods

From Marina to Noe Valley, Presidio to Twin Peaks — every SF neighborhood mapped.

curl https://microclimates.solofounders.com/neighborhoods

Includes: mission, castro, marina, soma, haight, noe_valley, outer_sunset, inner_richmond, north_beach, pacific_heights, potrero, dogpatch, bayview, twin_peaks, presidio, tenderloin, chinatown, japantown, cole_valley, glen_park, and 30 more.

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Response Format

Single Neighborhood

{
  "updated": "2026-01-25T23:00:00.000Z",
  "neighborhood": "outer_sunset",
  "name": "Outer Sunset",
  "temp_f": 52,
  "humidity": 78,
  "pm2_5": 8.3,
  "aqi": 35,
  "aqi_category": "Good",
  "sensor_count": 15
}

All Neighborhoods

{
  "updated": "2026-01-25T23:00:00.000Z",
  "neighborhoods": {
    "mission": { "temp_f": 58, "humidity": 52, "pm2_5": 12.1, "aqi": 50, "aqi_category": "Good", "sensor_count": 8 },
    "outer_sunset": { "temp_f": 52, "humidity": 78, "pm2_5": 8.3, "aqi": 35, "aqi_category": "Good", "sensor_count": 15 },
    "marina": { "temp_f": 55, "humidity": 65, "pm2_5": 18.5, "aqi": 64, "aqi_category": "Moderate", "sensor_count": 6 }
  }
}

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Air Quality

Each response includes real-time air quality data from PurpleAir sensors.

Response Fields

Field	Description
pm2_5	PM2.5 concentration in µg/m³ (10-minute rolling average)
aqi	Air Quality Index (0-500 scale)
aqi_category	Human-readable AQI category

AQI Categories

AQI Range	Category	Description
0–50	Good	Air quality is satisfactory
51–100	Moderate	Acceptable; moderate health concern for sensitive individuals
101–150	Unhealthy for Sensitive Groups	Sensitive groups may experience health effects
151–200	Unhealthy	Everyone may begin to experience health effects
201–300	Very Unhealthy	Health alert; everyone may experience serious effects
301+	Hazardous	Health emergency; entire population affected

Calculation Method

AQI is calculated from PM2.5 using the US EPA formula:

1. The pm2.5_10minute field (10-minute rolling average) is used for real-time responsiveness
2. PM2.5 concentration is mapped to AQI breakpoints per EPA standards
3. Linear interpolation determines the final AQI value

This gives you accurate, hyperlocal air quality — not a city-wide average from a distant monitoring station.

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Self-Hosting

Want to run your own instance?

1. Clone & Install

git clone https://github.com/solo-founders/sf-microclimates.git
cd sf-microclimates
npm install

2. Get a PurpleAir API Key

This API uses PurpleAir sensors. Sign up at develop.purpleair.com — free for personal use.

3. Create KV Namespace

wrangler kv:namespace create "CACHE"

Add the output to wrangler.toml:

[[kv_namespaces]]
binding = "CACHE"
id = "your-kv-namespace-id"

4. Set Your API Key

wrangler secret put PURPLEAIR_API_KEY

5. Deploy

wrangler deploy

Local Development

echo "PURPLEAIR_API_KEY=your-key" > .dev.vars
wrangler dev

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Configuration

Variable	Default	Description
CACHE_TTL_SECONDS	3600	Cache duration (1 hour)
RATE_LIMIT_PER_MINUTE	60	Max requests per IP

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How It Works

1. Request comes in → rate limit check
2. Check Cloudflare KV cache → return if fresh
3. Cache miss → fetch outdoor sensors from PurpleAir (location_type=0)
4. Group sensors by neighborhood GPS bounding boxes
5. Calculate averages, cache for 1 hour
6. Return JSON with CORS headers

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Fork for Your City

LA, Seattle, NYC, Chicago, Austin — every city has microclimates.

The neighborhood bounding boxes are in src/index.ts. To adapt:

1. Update SF_NEIGHBORHOODS with your city's areas + GPS coordinates
2. Change the PurpleAir bounding box to your city
3. Update branding
4. Deploy

PRs welcome! We'd love to see la-microclimates, nyc-microclimates, etc.

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Credits

• Sensor data: PurpleAir
• Infrastructure: Cloudflare Workers
• Built by: Solo Founders

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License

MIT — use it however you want.