diff --git a/assets/js/config.js b/assets/js/config.js
index 25ebe4f..7b15e5c 100644
--- a/assets/js/config.js
+++ b/assets/js/config.js
@@ -128,6 +128,7 @@ export const UTCI_ENVIRONMENTS = {
   beach:    { label: 'Beach / Lakeside',  dirFactor: 1.12, difFactor: 1.06, globFactor: 1.10, taOffset:  0.0, note: 'Reflected radiation from water and sand surfaces increases effective solar load - no shade, higher UV dose' },
   river:    { label: 'River / Riverbank', dirFactor: 0.50, difFactor: 0.60, globFactor: 0.55, taOffset: -2.5, note: 'Shaded riverbank estimate - canopy and valley walls reduce direct sun, evaporative cooling from water surface lowers apparent air temp' },
   desert:   { label: 'Desert / Arid',     dirFactor: 1.22, difFactor: 1.10, globFactor: 1.18, taOffset:  3.5, note: 'Extreme radiation load from high albedo sand and bare ground - ground-level heat significantly raises effective felt temperature' },
+  openwater: { label: 'Open Water',       dirFactor: 1.14, difFactor: 1.08, globFactor: 1.12, taOffset:  0.0, note: 'Open water - full solar exposure with additional radiation reflected from the water surface, no shade or shelter, no ground heat contribution' },
 };
 
 // Maps OUTDOORS_VARIANTS keys to a default UTCI_ENVIRONMENTS key.