diff --git a/notebooks/wp5/glacier_distribution.ipynb b/notebooks/wp5/glacier_distribution.ipynb
index bd5db30..a37a5b1 100644
--- a/notebooks/wp5/glacier_distribution.ipynb
+++ b/notebooks/wp5/glacier_distribution.ipynb
@@ -129,7 +129,9 @@
     "    date = years + months + days\n",
     "    date = date.where(~date.str.startswith(\"-\"))\n",
     "    columns.append(pd.to_datetime(date))\n",
-    "gdf[\"year\"] = pd.DataFrame(columns).mean().dt.year.astype(\"Int64\")"
+    "dates = pd.DataFrame(columns).mean()\n",
+    "gdf[\"decimal_year\"] = dates.year + (dates.dayofyear - 1) / (364 + dates.is_leap_year)\n",
+    "gdf[\"year\"] = dates.dt.year.astype(\"Int64\")"
    ]
   },
   {
@@ -345,7 +347,9 @@
     "grouped = gdf[[\"year\", \"AREA\", \"region\"]].groupby(\"region\")\n",
     "means = {\n",
     "    \"arithmetic\": grouped[\"year\"].mean(),\n",
-    "    \"weighted\": grouped.apply(weighted_average, \"year\", \"AREA\", include_groups=False),\n",
+    "    \"weighted\": grouped.apply(\n",
+    "        weighted_average, \"decimal_year\", \"AREA\", include_groups=False\n",
+    "    ),\n",
     "}\n",
     "text = []\n",
     "for label, mean in means.items():\n",