From 0b8e01256923abe09588f89e3d5fee81a1aaec7e Mon Sep 17 00:00:00 2001
From: hermes-explorigin <tim+hermes@thecookiejar.me>
Date: Tue, 18 Aug 2026 17:44:42 +0000
Subject: [PATCH] Show light drizzle icon on 7-day forecast when rain/storm
 chance is low

---
 src/components/DailyForecast.svelte |  2 +-
 src/lib/api/weather-codes.js        | 21 +++++++++++++++++++--
 tests/lib/api/weather-codes.test.js | 17 +++++++++++++++++
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/components/DailyForecast.svelte b/src/components/DailyForecast.svelte
index 8a23a62..3fe8ae2 100644
--- a/src/components/DailyForecast.svelte
+++ b/src/components/DailyForecast.svelte
@@ -29,7 +29,7 @@
     <div class="daily-list">
       {#each daily.time as day, i}
         {#if i < 7}
-          {@const info = getWeatherInfo(daily.weather_code[i])}
+          {@const info = getWeatherInfo(daily.weather_code[i], precip)}
           {@const tempMax = Math.round(daily.temperature_2m_max[i])}
           {@const tempMin = Math.round(daily.temperature_2m_min[i])}
           {@const precip = daily.precipitation_probability_max?.[i] || 0}
diff --git a/src/lib/api/weather-codes.js b/src/lib/api/weather-codes.js
index 9eb1d6e..809d5aa 100644
--- a/src/lib/api/weather-codes.js
+++ b/src/lib/api/weather-codes.js
@@ -39,8 +39,25 @@ const CODE_MAP = {
  * @param {number} code - WMO weather code (0-99)
  * @returns {{ icon: string, label: string, desc: string }}
  */
-export function getWeatherInfo(code) {
-  return CODE_MAP[code] || { icon: '❓', label: 'Unknown', desc: 'Unknown conditions' }
+// Codes that render as a rain/storm icon but are downgraded to light drizzle
+// when the forecast's precipitation chance is low — a 17% "chance of rain"
+// shouldn't display as a full rain icon.
+const RAIN_CODES = new Set([56, 57, 61, 63, 65, 66, 67, 80, 81, 82, 95, 96, 99])
+const LOW_CHANCE_PRECIP = 35
+
+/**
+ * Get weather display info for a WMO code.
+ * @param {number} code - WMO weather code (0-99)
+ * @param {number|null} prob - precipitation chance (%) for the period. When a
+ *   rain/storm code has only a low chance, show light drizzle instead.
+ * @returns {{ icon: string, label: string, desc: string }}
+ */
+export function getWeatherInfo(code, prob = null) {
+  const info = CODE_MAP[code] || { icon: '❓', label: 'Unknown', desc: 'Unknown conditions' }
+  if (prob != null && prob < LOW_CHANCE_PRECIP && RAIN_CODES.has(code)) {
+    return { icon: CODE_MAP[51].icon, label: 'Light Drizzle', desc: 'Chance of light rain' }
+  }
+  return info
 }
 
 /**
diff --git a/tests/lib/api/weather-codes.test.js b/tests/lib/api/weather-codes.test.js
index 4db1a75..3656751 100644
--- a/tests/lib/api/weather-codes.test.js
+++ b/tests/lib/api/weather-codes.test.js
@@ -56,6 +56,23 @@ describe('weather-codes', () => {
       expect(getWeatherInfo(81).icon).toBe('🌧️')
       expect(getWeatherInfo(82).icon).toBe('⛈️')
     })
+
+    it('downgrades rain to light drizzle when precip chance is low', () => {
+      const info = getWeatherInfo(63, 17)
+      expect(info.icon).toBe('🌦️')
+      expect(info.label).toBe('Light Drizzle')
+      expect(info.desc).toBe('Chance of light rain')
+    })
+
+    it('keeps full rain/storm icon when precip chance is high', () => {
+      expect(getWeatherInfo(63, 60).icon).toBe('🌧️')
+      expect(getWeatherInfo(95, 70).icon).toBe('⛈️')
+    })
+
+    it('does not downgrade when no probability is provided', () => {
+      expect(getWeatherInfo(63).icon).toBe('🌧️')
+      expect(getWeatherInfo(82).icon).toBe('⛈️')
+    })
   })
 
   describe('getWeatherSeverity', () => {