diff --git a/README.md b/README.md
index 43b0418..8891ea7 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,18 @@ The repo associated with training the models run here is https://github.com/open
 The model checkpoints are hosted at:
 https://huggingface.co/openclimatefix/cloudcasting_uk
 
+## Environment Variables
+
+The following environment variables are used in the app:
+
+- `SATELLITE_ZARR_PATH`: The path to the satellite data in Zarr format.
+- `OUTPUT_PREDICTION_DIRECTORY`: The directory where results are saved. 
+
+### Optional Environment Variables
+
+- `SATELLITE_SCALE_FACTOR`: The scale factor for the satellite data. Defaults to 1023. 
+- `SATELLITE_15_ZARR_PATH`: The path to the 15 minute satellite data in Zarr format. If 
+this is not set then the `SATELLITE_ZARR_PATH` is used by `.zarr` is repalced with `_15.zarr`
 
 ## Installation
 
diff --git a/src/cloudcasting_app/data.py b/src/cloudcasting_app/data.py
index 7f6a4c6..3a6f092 100644
--- a/src/cloudcasting_app/data.py
+++ b/src/cloudcasting_app/data.py
@@ -1,6 +1,7 @@
 import logging
 import shutil
 import os
+import yaml
 
 import fsspec
 import numpy as np
@@ -76,6 +77,12 @@ def prepare_satellite_data(t0: pd.Timestamp):
     # Load data the data for more preprocessing
     ds = xr.open_zarr(sat_path)
 
+    # make sure area attrs are yaml string
+    if "area" in ds.data.attrs and isinstance(ds.data.attrs["area"], dict):
+        logger.warning("Converting area attribute to YAML string, "
+            "we should do this in the satellite consumer.")
+        ds.data.attrs["area"] = yaml.dump(ds.data.attrs["area"])
+
     # Crop the input area to expected
     ds = crop_input_area(ds)
 
@@ -83,7 +90,12 @@ def prepare_satellite_data(t0: pd.Timestamp):
     ds = ds.sel(variable=channel_order)
 
     # Scale the satellite data from 0-1
-    ds = ds / 1023
+    scale_factor = int(os.environ.get("SATELLITE_SCALE_FACTOR", 1023))
+    logger.info(
+        f"Scaling satellite data by {scale_factor} to be between 0 and 1"
+    )
+    ds = ds / scale_factor
+
 
     # Resave
     ds = ds.compute()
@@ -107,8 +119,10 @@ def download_all_sat_data() -> bool:
     # Set variable to track whether the satellite download is successful
     sat_available = False
 
+    # get paths
+    sat_5_dl_path, sat_15_dl_path  = get_satellite_source_paths()
+
     # download 5 minute satellite data
-    sat_5_dl_path = os.environ["SATELLITE_ZARR_PATH"]
     fs, _ = fsspec.core.url_to_fs(sat_5_dl_path)
     if fs.exists(sat_5_dl_path):
         sat_available = True
@@ -121,7 +135,6 @@ def download_all_sat_data() -> bool:
         logger.info("No 5-minute data available")
 
     # Also download 15-minute satellite if it exists
-    sat_15_dl_path = sat_5_dl_path.replace(".zarr", "_15.zarr")
     if fs.exists(sat_15_dl_path):
         sat_available = True
         logger.info("Downloading 15-minute satellite data")
@@ -226,3 +239,14 @@ def get_input_data(ds: xr.Dataset, t0: pd.Timestamp):
     X = np.nan_to_num(X, nan=-1)
 
     return torch.Tensor(X)
+
+
+def get_satellite_source_paths() -> (str | None, str | None):
+    """ Get the paths to the satellite data from environment variables"""
+    sat_source_path_5 = os.getenv("SATELLITE_ZARR_PATH", None)
+    sat_source_path_15 = os.getenv("SATELLITE_15_ZARR_PATH", None)
+    if sat_source_path_15 is None and sat_source_path_5 is not None:
+        sat_source_path_15 = sat_source_path_5.replace(".zarr", "_15.zarr")
+    logger.info(
+        f"Satellite source paths: 5-minute: {sat_source_path_5}, 15-minute: {sat_source_path_15}")
+    return sat_source_path_5, sat_source_path_15