🌤 Weather Trading Bot — Polymarket

Automated weather market trading bot for Polymarket. Finds mispriced temperature outcomes using Open-Meteo forecasts, filters trades with Expected Value analysis, and sizes positions with the Kelly Criterion.

No SDK. No black box. ~400 lines of pure Python.

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How It Works

Polymarket runs markets like "Will the highest temperature in NYC be between 40–41°F on March 4?" These markets are often mispriced — the forecast says 78% likely, but the market is trading at 8 cents.

The bot:

1. Fetches 4-day forecasts from Open-Meteo (free, no API key)
2. Finds the matching temperature bucket on Polymarket
3. Calculates Expected Value — skips the trade if EV is negative
4. Calculates Kelly Criterion — sizes the position based on edge strength
5. Runs a full $1,000 simulation against real market prices before you risk anything

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Kelly + EV Logic

Expected Value — is this trade mathematically profitable?

EV = (our_probability × net_payout) − (1 − our_probability)

Kelly Criterion — how much of the balance to bet?

Kelly % = (p × b − q) / b

We use fractional Kelly (25%) and cap each position at 10% of balance.

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Installation

git clone https://github.com/alteregoeth-ai/weatherbot
cd weatherbot
pip install requests

Add your settings to config.json:

{
  "entry_threshold": 0.15,
  "exit_threshold": 0.45,
  "locations": "NYC,Chicago,Seattle,Atlanta,Dallas,Miami"
}

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Usage

# Paper mode — shows signals + Kelly/EV analysis, no trades
python weather_bot_v2.py

# Simulation mode — executes trades, updates virtual $1,000 balance
python weather_bot_v2.py --live

# Show open positions and PnL
python weather_bot_v2.py --positions

# Reset simulation back to $1,000
python weather_bot_v2.py --reset

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Dashboard

Open sim_dashboard.html in any browser to see the simulation in real time:

• Balance chart with floating +/- labels on each trade
• Open positions with Kelly %, EV, and price progress bar
• Full trade history with W/L tracking
• No server needed — pure HTML/JS

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Configuration

Parameter	Default	Description
entry_threshold	0.15	Buy below this price
exit_threshold	0.45	Sell above this price
locations	NYC,...	Cities to scan
max_trades_per_run	5	Max trades per run
min_hours_to_resolution	2	Skip if resolves too soon

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Live Trading

The bot runs in simulation mode by default. To execute real trades, add Polymarket CLOB integration:

pip install py-clob-client

Then replace the paper mode line in weather_bot_v2.py with your CLOB buy function. Full guide in the article linked below.

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APIs Used

API	Auth	Purpose
Open-Meteo	None	Weather forecasts
Polymarket Gamma	None	Market data
Polymarket CLOB	Wallet key	Live trading (optional)

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Disclaimer

This is not financial advice. Prediction markets carry real risk. Run the simulation thoroughly before committing real capital.