diff --git a/src/forecaster/Config.py b/src/forecaster/Config.py
index 1549d9811aa5d1c193a44ad45d0d7773236c0612..0d80b8fe62ff2e8313ec6a7b1b0278fea7c16950 100644
--- a/src/forecaster/Config.py
+++ b/src/forecaster/Config.py
@@ -12,3 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
+
+# FORECAST_TO_HISTORY_RATIO indicates the size of the trainset.
+# For example a history ratio of 10 would imply that the train-set will be 10 times bigger
+# than the forecast period and the test-set.
+DEFAULT_FORECAST_TO_HISTORY_RATIO = 10
+FORECAST_TO_HISTORY_RATIO = int(os.environ.get('FORECAST_TO_HISTORY_RATIO', DEFAULT_FORECAST_TO_HISTORY_RATIO))