diff --git a/weather/rain-window-alert/start.js b/weather/rain-window-alert/start.js
new file mode 100644
index 0000000..98c3d43
--- /dev/null
+++ b/weather/rain-window-alert/start.js
@@ -0,0 +1,17 @@
+const states = global.get('homeassistant.homeAssistant.states')
+const precipType = states['sensor.home_tempest_precipitation_type'].state
+const precipIntensity = states['sensor.home_tempest_cloud_sensors_precipitation_intensity'].state
+
+const typeStatesRaining = ['rain','hail','rain_hail']
+const intensityStatesRaining = ['very_light','light','moderate','heavy','very_heavy','extreme']
+
+const isTypeRaining = typeStatesRaining.includes(precipType)
+const isIntensityRaining = intensityStatesRaining.includes(precipIntensity)
+
+const isRaining = isTypeRaining || isIntensityRaining
+
+flow.set('typeStatesRaining', typeStatesRaining)
+flow.set('intensityStatesRaining', intensityStatesRaining)
+flow.set('isRaining', isRaining)
+
+return null
\ No newline at end of file