diff --git a/climax/core/constants.py b/climax/core/constants.py
index abecd3b31e8b77cd71958c960c483207792bb5d3..e77c10d986ff5006bae98211a517ee65c38aa818 100644
--- a/climax/core/constants.py
+++ b/climax/core/constants.py
@@ -61,3 +61,6 @@ PROJECTION = 'lambert_azimuthal_equal_area'
 
 # predictand variables: covered by observations
 PREDICTANDS = ['tasmin', 'tasmax', 'pr', 'tas']
+
+# threshold  defining the minimum amount of precipitation (mm) for a wet day
+WET_DAY_THRESHOLD = 1