The Outdoor Seating: Revenue-Loss Calculator

Days per year

Sun and glare

365 minus NOAA's count of days with 80% or more cloud cover, so it is the days with real sun. Low sun takes roughly 12% of a service out of use rather than killing the whole day. This is driven by sun angle, not temperature, so it happens on mild clear evenings too.

Wind

Regional estimate of days gusty enough to move menus, settings and umbrellas.

Rain

NOAA days with at least 0.01 inch of precipitation. About 30% of those cost a service — many are overnight or pass in twenty minutes.

Heat

NOAA days reaching 90°F or hotter, the point where shade on its own stops being enough. About half a service lost. Days in the 80s show up under Sun and glare instead, because shade handles them.

Cold

Estimated days with a high under 55°F. About 70% unusable.

All five are full-day equivalents: two ruined half-days count as one. Days outside the patio season are excluded, and a discount is applied for days that fall under more than one cause.

Recovered by screens

The share of the revenue lost to that cause that a screen brings back. Wind is highest, because a retained screen stops it almost entirely. Glare is nearly as high — blocking low sun is exactly what solar fabric does. Rain is partial: screens stop wind-driven rain well and vertical rain poorly. Heat is limited, because shade is not air conditioning. Cold is lowest — blocking wind makes a patio heater far more effective, but a 35°F night is still a 35°F night.