How SeasonMap scores climate comfort

1. Eight climate factors

For each destination and month we start from long-run monthly climate normals and score eight factors from 0 to 100: temperature (using the apparent / “feels-like” high where available), humidity, rainfall, sunshine, daylight, wind, snow, and air quality (mean US AQI). Each factor degrades gracefully — if a metric is missing for a place, it contributes a neutral score rather than breaking the result.

2. Travel-style weighting

The factors are blended into a weighted average, and the weights — plus the ideal temperature range — change with your travel style. A beach trip prizes warmth, sunshine and low rain; a city walking trip prefers mild temperatures; hiking rewards clear, dry, temperate conditions; winter / snow inverts the usual cold penalty so reliable snow counts as a plus. You can also tune the weights and ideal range yourself.

3. A feasibility penalty for genuine extremes

A plain weighted average can be fooled — a dry, sunny desert at 42 °C would “average away” its heat. So a feasibility factor multiplies the score down hard when conditions are genuinely unlivable (punishing heat, extreme cold), so a place can't look pleasant on paper when it isn't in practice.

4. Seasonality — this month vs. the other eleven

A month's comfort is also ranked against the destination's own other eleven months, and the final score is a variance-aware blend: places that are pleasant year-round barely use seasonality, while strongly seasonal places lean on it. That's why each destination has a clear best and worst month, not a flat line.

5. Tiers

The final 0–100 score maps to a letter tier for quick scanning — S and A are excellent, B/C are decent-to-mixed, and D/F flag months to avoid.

Data sources & limitations

• Climate normals come from Open-Meteo (ERA5 reanalysis); air quality is the monthly mean US Air Quality Index.
• These are normals, not a forecast — they describe a typical month, not the weather on your specific dates. Any given year can differ.
• Snowfall is our least-reliable metric and is partly modelled; treat snow scores as directional.
• Comfort scoring is opinionated by design — which is exactly why the weights are yours to change.