Field calculator

Optimal Rain Walking Speed

Estimate the walking or running speed that minimises relative wetness for a given rain, wind, body area, and walking direction.

W(v)=R L/(w v) · (A_t w + A_s |U sinθ| + A_f [v-U cosθ]+ + A_b [U cosθ-v]+)

Optional local weather

Location is only sent to this site's weather endpoint to fetch local weather and is not saved.

Manual input is always available.

Inputs

metres to travel.
mm/h; converted internally to m/s.
m/s maximum walking/running speed.
km/h equivalent; synced with m/s.
m/s vertical fall speed.
m/s horizontal component.
km/h equivalent; synced with m/s.
degrees. 0° behind, 90° crosswind, 180° into face.
degrees clockwise from north. Used only for weather wind conversion.
m² exposed upward area.
m² frontal body area.
m² rear body area.
m² side body area for crosswind.

Calculated optimum

m/s—
km/h—
Interpretation—

Relative wetness comparison

Casem/skm/hRelative wetness

Practical rule

  • In most rain, faster is better because you spend less time exposed.
  • The exception is strong rain blowing from behind, where matching the rain's horizontal speed can reduce front/back impact.
  • Rainfall intensity changes how wet you get, but usually not the optimal speed.
  • Let p = U·cos(θ) and K = A_t·w + A_s·abs(U·sin(θ)). Most cases favour v_max; if rain is strongly from behind and 0 < p < v_max, the best speed may be close to p.