diff --git a/src/anemoi/utils/dates.py b/src/anemoi/utils/dates.py
index 4614c4c..07c2871 100644
--- a/src/anemoi/utils/dates.py
+++ b/src/anemoi/utils/dates.py
@@ -162,11 +162,15 @@ def __init__(self, reference_dates, years=20):
         """
 
         self.reference_dates = reference_dates
-        self.years = (1, years + 1)
+
+        if isinstance(years, list):
+            self.years = years
+        else:
+            self.years = range(1, years + 1)
 
     def __iter__(self):
         for reference_date in self.reference_dates:
-            for year in range(*self.years):
+            for year in self.years:
                 if reference_date.month == 2 and reference_date.day == 29:
                     date = datetime.datetime(reference_date.year - year, 2, 28)
                 else:
@@ -246,3 +250,47 @@ def __init__(self, year, **kwargs):
             _description_
         """
         super().__init__(datetime.datetime(year, 9, 1), datetime.datetime(year, 11, 30), **kwargs)
+
+
+class ConcatDateTimes:
+    def __init__(self, *dates):
+        if len(dates) == 1 and isinstance(dates[0], list):
+            dates = dates[0]
+
+        self.dates = dates
+
+    def __iter__(self):
+        for date in self.dates:
+            yield from date
+
+
+class EnumDateTimes:
+    def __init__(self, dates):
+        self.dates = dates
+
+    def __iter__(self):
+        for date in self.dates:
+            yield as_datetime(date)
+
+
+def datetimes_factory(args):
+    if isinstance(args, dict):
+        name = args.get("name")
+
+        if name == "hindcast":
+            reference_dates = args["reference_dates"]
+            reference_dates = datetimes_factory(reference_dates)
+            years = args["years"]
+            return HindcastDatesTimes(reference_dates=reference_dates, years=years)
+
+        args = args.copy()
+        frequency = args.pop("frequency", 24)
+        args["increment"] = frequency
+        return DateTimes(**args)
+
+    if isinstance(args, list):
+        if all(isinstance(arg, dict) for arg in args):
+            return ConcatDateTimes(*[datetimes_factory(arg) for arg in args])
+        else:
+            return EnumDateTimes(args)
+    raise ValueError(f"Invalid dates provided : {args}")
diff --git a/tests/test_dates.py b/tests/test_dates.py
new file mode 100644
index 0000000..61331f7
--- /dev/null
+++ b/tests/test_dates.py
@@ -0,0 +1,92 @@
+from textwrap import dedent
+
+import yaml
+
+from anemoi.utils.dates import datetimes_factory
+
+
+def _(txt):
+    txt = dedent(txt)
+    config = yaml.safe_load(txt)
+    config = config["dates"]
+    return datetimes_factory(config)
+
+
+def test_date_1():
+    d = _(
+        """
+        dates:
+            - 2023-01-01
+            - 2023-01-02
+            - 2023-01-03
+    """
+    )
+    assert len(list(d)) == 3
+
+
+def test_date_2():
+    d = _(
+        """
+        dates:
+          start: 2023-01-01
+          end: 2023-01-07
+          frequency: 12
+          day_of_week: [monday, friday]
+    """
+    )
+    assert len(list(d)) == 4
+
+
+def test_date_3():
+    d = _(
+        """
+        dates:
+          - start: 2023-01-01
+            end: 2023-01-03
+            frequency: 24
+          - start: 2024-01-01T06:00:00
+            end: 2024-01-03T18:00:00
+            frequency: 6
+    """
+    )
+    assert len(list(d)) == 14
+
+
+def test_date_hindcast_1():
+    d = _(
+        """
+        dates:
+          - name: hindcast
+            reference_dates:
+              start: 2023-01-01
+              end: 2023-01-03
+              frequency: 24
+            years: 20
+    """
+    )
+    assert len(list(d)) == 60
+
+
+def test_date_hindcast_2():
+    d = _(
+        """
+        dates:
+          - name: hindcast
+            reference_dates:
+              start: 2023-01-01
+              end: 2023-01-03
+              frequency: 24
+            years: [2018, 2019, 2020, 2021]
+    """
+    )
+    assert len(list(d)) == 12
+
+
+if __name__ == "__main__":
+    test_functions = [
+        obj for name, obj in globals().items() if name.startswith("test_") and isinstance(obj, type(lambda: 0))
+    ]
+    for test_func in test_functions:
+        print(f"Running test: {test_func.__name__}")
+        test_func()
+    print("All tests passed!")