diff --git a/bigframes/core/compile/sqlglot/aggregations/windows.py b/bigframes/core/compile/sqlglot/aggregations/windows.py
index 6d6c507455..9c32788585 100644
--- a/bigframes/core/compile/sqlglot/aggregations/windows.py
+++ b/bigframes/core/compile/sqlglot/aggregations/windows.py
@@ -44,6 +44,7 @@ def apply_window_if_present(
         order_by = None
     elif window.is_range_bounded:
         order_by = get_window_order_by((window.ordering[0],))
+        order_by = remove_null_ordering_for_range_windows(order_by)
     else:
         order_by = get_window_order_by(window.ordering)
 
@@ -150,6 +151,30 @@ def get_window_order_by(
     return tuple(order_by)
 
 
+def remove_null_ordering_for_range_windows(
+    order_by: typing.Optional[tuple[sge.Ordered, ...]],
+) -> typing.Optional[tuple[sge.Ordered, ...]]:
+    """Removes NULL FIRST/LAST from ORDER BY expressions in RANGE windows.
+    Here's the support matrix:
+    ✅ sum(x) over (order by y desc nulls last)
+    🚫 sum(x) over (order by y asc nulls last)
+    ✅ sum(x) over (order by y asc nulls first)
+    🚫 sum(x) over (order by y desc nulls first)
+    """
+    if order_by is None:
+        return None
+
+    new_order_by = []
+    for key in order_by:
+        kargs = key.args
+        if kargs.get("desc") is True and kargs.get("nulls_first", False):
+            kargs["nulls_first"] = False
+        elif kargs.get("desc") is False and not kargs.setdefault("nulls_first", True):
+            kargs["nulls_first"] = True
+        new_order_by.append(sge.Ordered(**kargs))
+    return tuple(new_order_by)
+
+
 def _get_window_bounds(
     value, is_preceding: bool
 ) -> tuple[typing.Union[str, sge.Expression], typing.Optional[str]]:
diff --git a/bigframes/core/compile/sqlglot/compiler.py b/bigframes/core/compile/sqlglot/compiler.py
index b3b813a1c0..e77370892c 100644
--- a/bigframes/core/compile/sqlglot/compiler.py
+++ b/bigframes/core/compile/sqlglot/compiler.py
@@ -356,6 +356,9 @@ def compile_window(node: nodes.WindowOpNode, child: ir.SQLGlotIR) -> ir.SQLGlotI
                 observation_count = windows.apply_window_if_present(
                     sge.func("SUM", is_observation), window_spec
                 )
+                observation_count = sge.func(
+                    "COALESCE", observation_count, sge.convert(0)
+                )
             else:
                 # Operations like count treat even NULLs as valid observations
                 # for the sake of min_periods notnull is just used to convert
diff --git a/bigframes/core/compile/sqlglot/expressions/comparison_ops.py b/bigframes/core/compile/sqlglot/expressions/comparison_ops.py
index 81bc9e0f56..8fda3b80dd 100644
--- a/bigframes/core/compile/sqlglot/expressions/comparison_ops.py
+++ b/bigframes/core/compile/sqlglot/expressions/comparison_ops.py
@@ -89,6 +89,9 @@ def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.ge_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     left_expr = _coerce_bool_to_int(left)
     right_expr = _coerce_bool_to_int(right)
     return sge.GTE(this=left_expr, expression=right_expr)
@@ -96,6 +99,9 @@ def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.gt_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     left_expr = _coerce_bool_to_int(left)
     right_expr = _coerce_bool_to_int(right)
     return sge.GT(this=left_expr, expression=right_expr)
@@ -103,6 +109,9 @@ def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.lt_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     left_expr = _coerce_bool_to_int(left)
     right_expr = _coerce_bool_to_int(right)
     return sge.LT(this=left_expr, expression=right_expr)
@@ -110,6 +119,9 @@ def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.le_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     left_expr = _coerce_bool_to_int(left)
     right_expr = _coerce_bool_to_int(right)
     return sge.LTE(this=left_expr, expression=right_expr)
diff --git a/bigframes/core/compile/sqlglot/expressions/numeric_ops.py b/bigframes/core/compile/sqlglot/expressions/numeric_ops.py
index 16f7dec717..f7c763e207 100644
--- a/bigframes/core/compile/sqlglot/expressions/numeric_ops.py
+++ b/bigframes/core/compile/sqlglot/expressions/numeric_ops.py
@@ -388,6 +388,9 @@ def _(expr: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.add_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     if left.dtype == dtypes.STRING_DTYPE and right.dtype == dtypes.STRING_DTYPE:
         # String addition
         return sge.Concat(expressions=[left.expr, right.expr])
@@ -442,6 +445,9 @@ def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.floordiv_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     left_expr = _coerce_bool_to_int(left)
     right_expr = _coerce_bool_to_int(right)
 
@@ -525,6 +531,9 @@ def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.mul_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     left_expr = _coerce_bool_to_int(left)
     right_expr = _coerce_bool_to_int(right)
 
@@ -548,6 +557,9 @@ def _(expr: TypedExpr, n_digits: TypedExpr) -> sge.Expression:
 
 @register_binary_op(ops.sub_op)
 def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    if left.expr == sge.null() or right.expr == sge.null():
+        return sge.null()
+
     if dtypes.is_numeric(left.dtype) and dtypes.is_numeric(right.dtype):
         left_expr = _coerce_bool_to_int(left)
         right_expr = _coerce_bool_to_int(right)
diff --git a/tests/unit/core/compile/sqlglot/aggregations/test_windows.py b/tests/unit/core/compile/sqlglot/aggregations/test_windows.py
index e6343a63d7..d1204c6010 100644
--- a/tests/unit/core/compile/sqlglot/aggregations/test_windows.py
+++ b/tests/unit/core/compile/sqlglot/aggregations/test_windows.py
@@ -127,7 +127,7 @@ def test_apply_window_if_present_range_bounded(self):
         )
         self.assertEqual(
             result.sql(dialect="bigquery"),
-            "value OVER (ORDER BY `col1` ASC NULLS LAST RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)",
+            "value OVER (ORDER BY `col1` ASC RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)",
         )
 
     def test_apply_window_if_present_range_bounded_timedelta(self):
@@ -142,7 +142,7 @@ def test_apply_window_if_present_range_bounded_timedelta(self):
         )
         self.assertEqual(
             result.sql(dialect="bigquery"),
-            "value OVER (ORDER BY `col1` ASC NULLS LAST RANGE BETWEEN 86400000000 PRECEDING AND 43200000000 FOLLOWING)",
+            "value OVER (ORDER BY `col1` ASC RANGE BETWEEN 86400000000 PRECEDING AND 43200000000 FOLLOWING)",
         )
 
     def test_apply_window_if_present_all_params(self):
diff --git a/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_groupby_rolling/out.sql b/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_groupby_rolling/out.sql
index e8fabd1129..0dca6d9d49 100644
--- a/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_groupby_rolling/out.sql
+++ b/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_groupby_rolling/out.sql
@@ -22,10 +22,13 @@ WITH `bfcte_0` AS (
   SELECT
     *,
     CASE
-      WHEN SUM(CAST(NOT `bfcol_7` IS NULL AS INT64)) OVER (
-        PARTITION BY `bfcol_9`
-        ORDER BY `bfcol_9` ASC NULLS LAST, `rowindex` ASC NULLS LAST
-        ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
+      WHEN COALESCE(
+        SUM(CAST(NOT `bfcol_7` IS NULL AS INT64)) OVER (
+          PARTITION BY `bfcol_9`
+          ORDER BY `bfcol_9` ASC NULLS LAST, `rowindex` ASC NULLS LAST
+          ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
+        ),
+        0
       ) < 3
       THEN NULL
       ELSE COALESCE(
@@ -42,10 +45,13 @@ WITH `bfcte_0` AS (
   SELECT
     *,
     CASE
-      WHEN SUM(CAST(NOT `bfcol_8` IS NULL AS INT64)) OVER (
-        PARTITION BY `bfcol_9`
-        ORDER BY `bfcol_9` ASC NULLS LAST, `rowindex` ASC NULLS LAST
-        ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
+      WHEN COALESCE(
+        SUM(CAST(NOT `bfcol_8` IS NULL AS INT64)) OVER (
+          PARTITION BY `bfcol_9`
+          ORDER BY `bfcol_9` ASC NULLS LAST, `rowindex` ASC NULLS LAST
+          ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
+        ),
+        0
       ) < 3
       THEN NULL
       ELSE COALESCE(
diff --git a/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_range_rolling/out.sql b/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_range_rolling/out.sql
index 581c81c6b4..fe4cea08cb 100644
--- a/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_range_rolling/out.sql
+++ b/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_range_rolling/out.sql
@@ -6,14 +6,17 @@ WITH `bfcte_0` AS (
   SELECT
     *,
     CASE
-      WHEN SUM(CAST(NOT `bfcol_1` IS NULL AS INT64)) OVER (
-        ORDER BY UNIX_MICROS(`bfcol_0`) ASC NULLS LAST
-        RANGE BETWEEN 2999999 PRECEDING AND CURRENT ROW
+      WHEN COALESCE(
+        SUM(CAST(NOT `bfcol_1` IS NULL AS INT64)) OVER (
+          ORDER BY UNIX_MICROS(`bfcol_0`) ASC
+          RANGE BETWEEN 2999999 PRECEDING AND CURRENT ROW
+        ),
+        0
       ) < 1
       THEN NULL
       ELSE COALESCE(
         SUM(`bfcol_1`) OVER (
-          ORDER BY UNIX_MICROS(`bfcol_0`) ASC NULLS LAST
+          ORDER BY UNIX_MICROS(`bfcol_0`) ASC
           RANGE BETWEEN 2999999 PRECEDING AND CURRENT ROW
         ),
         0
diff --git a/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_skips_nulls_op/out.sql b/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_skips_nulls_op/out.sql
index 788eb49ddf..bf1e76c55c 100644
--- a/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_skips_nulls_op/out.sql
+++ b/tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_skips_nulls_op/out.sql
@@ -7,7 +7,10 @@ WITH `bfcte_0` AS (
   SELECT
     *,
     CASE
-      WHEN SUM(CAST(NOT `int64_col` IS NULL AS INT64)) OVER (ORDER BY `rowindex` ASC NULLS LAST ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) < 3
+      WHEN COALESCE(
+        SUM(CAST(NOT `int64_col` IS NULL AS INT64)) OVER (ORDER BY `rowindex` ASC NULLS LAST ROWS BETWEEN 2 PRECEDING AND CURRENT ROW),
+        0
+      ) < 3
       THEN NULL
       ELSE COALESCE(
         SUM(`int64_col`) OVER (ORDER BY `rowindex` ASC NULLS LAST ROWS BETWEEN 2 PRECEDING AND CURRENT ROW),