Conditions

Why an A+?

Every city page shows a letter grade for the current weather. Here's how we get there. Nothing magic, just temperature, precipitation and wind run through a transparent formula.

The grades

  • A+

    Perfect.

    92+ score. Cool, dry, no real wind. Don't waste this.

  • A

    Excellent.

    84-91. One small thing off-peak — slight chill, slight breeze. Still almost rude not to go.

  • B+

    Solid.

    75-83. Warm or cool side of comfortable, maybe a hint of damp. No good reason to stay in.

  • B

    Good.

    65-74. Noticeable weather (light rain, a real breeze, mid-summer heat) but nothing severe.

  • C+

    Workable.

    55-64. Less ideal — proper rain, real wind, or temperatures that bite. Still doable.

  • C

    Bring layers.

    42-54. Honest weather, not friendly. Shorter runs, dress smart, hydrate.

  • D

    Tough.

    Below 42. Storm, blizzard, extreme heat. Short loop. Out and back. Still counts.

How it's calculated

We start with a temperature score from 0 to 100. Then we subtract penalties for precipitation and wind. Whatever's left maps onto the letter scale.

Temperature score

  • 8-18°C · 100 points. The ideal running band.
  • 4-8°C, 18-24°C · Around 90 points. Still very comfortable.
  • 0-4°C, 24-28°C · 75-80 points. Cold or warm enough to notice.
  • < 0°C, > 28°C · Drops fast, floors at 30. Harsh on the body but never zero.

Precipitation penalty

  • Light drizzle · -8
  • Rain · -18
  • Snow · -22
  • Thunderstorm · -35
  • Fog · -5

Wind penalty

  • 25 km/h-35 km/h · -7
  • 35 km/h-50 km/h · -15
  • > 50 km/h · -30

Examples

  • A+13°C, cloudy, 8 km/h breeze in London. Score 100, no penalties. Perfect.
  • B+22°C, sunny, 18 km/h wind in Madrid. Score 78. Solid running weather.
  • C30°C, sunny in Phoenix at noon. Score 50. Workable, but go before sunrise.
  • D-12°C, snowing, 40 km/h wind in Minneapolis. Score 18. Tough. Short loop, out and back.

Honest caveat

The grade is a guide, not gospel. It doesn't know whether you're hydrated, how you slept, or whether your knee hurts. It's a starting point, not an excuse. The answer to should-I-run is still yes.

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