diff --git a/.gitignore b/.gitignore
index 8f6a37b..d76d74a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,4 @@ __py*
 *.log
 *.zip
 dist/
+dwd/
diff --git a/src/main/python/fallback_csv.py b/src/main/python/fallback_csv.py
index 47a3ed9..3a09b23 100644
--- a/src/main/python/fallback_csv.py
+++ b/src/main/python/fallback_csv.py
@@ -1,16 +1,53 @@
 import glob
+import datetime
 import os
 
-def write_cachefile(cache_dir, data):
-    pass
+SKIP_LINES = 13
 
-def generate(master_dir, from_time, to_time, cache_dir_fullpath):
+def cache_content(from_time, to_time, data, dtype):
+
+    return_string = ""
+
+    skip_count = 0
+    for d in data:
+
+        date, temp, hum = d
+
+        # skip outside timeframe #
+        if date < from_time or date > to_time:
+            continue
+
+        # skip lines #
+        if skip_count < SKIP_LINES:
+            return_string += "\n"
+            skip_count += 1
+            continue
+
+        if dtype == "lufttemperatur-aussen":
+            content_number = temp
+        elif dtype == "luftfeuchte":
+            content_number = hum
+        else:
+            raise ValueError("Bad dtype: {}".format(dtype))
+
+        date_cache_format = date.strftime("%d.%m.%Y %H:%M")
+        content_str = "{:1f}".format(content_number).replace(".",",")
+        return_string += "{};{}\n".format(date_cache_format, content_str)
+
+    return return_string
+
+def generate(master_dir, from_time, to_time, cache_file, dtype):
 
     timeframes = []
 
+    if not os.path.isdir(master_dir):
+        os.mkdir(master_dir)
+
     # read files
-    files = glob.glob(master_dir + "/*.txt"):
-    print(files)
+    files = glob.glob(master_dir + "/produkt_tu_stunde*.txt")
+
+    if not files:
+        raise ValueError("Keine DWD_Datei in: {} gefunden. Bitte herunterladen und entpacken! https://www.dwd.de/DE/leistungen/klimadatendeutschland/klarchivstunden.html;jsessionid=C423E76B30D18F24C43F4E7E36744C8C.live21073?nn=16102")
 
     for fname in files:
 
@@ -34,7 +71,10 @@ def generate(master_dir, from_time, to_time, cache_dir_fullpath):
                 station_id, fulldate, dunno, temp, hum, dunno2 = line.split(";")
 
                 # parse date #
-                date = datetime.datetime.strptime(fulldate, "%y%m%d%H")
+                date = datetime.datetime.strptime(fulldate, "%Y%m%d%H")
+
+                # append data #
+                data.append((date, float(temp), float(hum)))
 
                 # set start and end #
                 if not start and date:
@@ -47,12 +87,8 @@ def generate(master_dir, from_time, to_time, cache_dir_fullpath):
 
     # find a fitting frame #
     for start, end, data in timeframes:
+        print(start, end)
         if from_time >= start and to_time <= end:
-            write_cachefile(cache_dir_fullpath, data)
-            return
+            return cache_content(from_time, to_time, data, dtype)
 
     raise ValueError("Keine Datei mit passenden Daten gefunden. Bitte Readme lesen")
-
-
-    # generate a correct cache file from it return
-    # if no suiteable file is found return an appropriate error
diff --git a/src/main/python/input_backend.py b/src/main/python/input_backend.py
index 1010255..da17e04 100644
--- a/src/main/python/input_backend.py
+++ b/src/main/python/input_backend.py
@@ -8,6 +8,7 @@ import localization.de as de
 from dbfread import DBF
 import timeutils
 import codecs
+import fallback_csv
 
 line_colors = ['b', 'r', 'g', 'c', 'm', 'y']
 tname       = CFG("temperatur_plot_name")
@@ -130,10 +131,11 @@ def processExternalData(datapoints, plotNameKey, fromTime, toTime, dtype, qtText
         # check response code #
         if r.status_code != 200 or "nicht gefunden" in r.text.lower():
             qtTextBrowser.append(de.failed_to_retrieve.format("NOT FOUND"))
-            raise ValueError("FAILED TO RETRIEVE DATA")
-
-        qtTextBrowser.append(de.pg_request.format(url))
-        content = r.content.decode('utf-8', "ignore") # ignore bad bytes
+            qtTextBrowser.append("Versuche von DWD-Datei zu laden - Dass kann einen Moment dauern")
+            content = fallback_csv.generate(CFG("dwd_dir"), fromTime, toTime, cacheFile, dtype)
+        else:
+            qtTextBrowser.append(de.pg_request.format(url))
+            content = r.content.decode('utf-8', "ignore") # ignore bad bytes
 
         # cache data #
         if not os.path.isdir(cacheDir):
@@ -141,7 +143,7 @@ def processExternalData(datapoints, plotNameKey, fromTime, toTime, dtype, qtText
         with open(fullpath, 'w') as f:
             f.write(content)
 
-    else:
+    if os.path.isfile(fullpath):
 
         # get data from cache otherwise
         qtTextBrowser.append(de.cache_hit.format(cacheFile))
diff --git a/ths_config.txt b/ths_config.txt
index f87f698..c9723f0 100644
--- a/ths_config.txt
+++ b/ths_config.txt
@@ -105,3 +105,4 @@ fig_x_height_inches         = 12100
 fig_y_height_inches         =  8075
 default_target_dir          = UseSourceDir
 default_source_dir          = "."
+dwd_dir = "./dwd/"