diff --git a/agenda/__init__.py b/agenda/__init__.py
index bdf2b5e..ad0cf1e 100644
--- a/agenda/__init__.py
+++ b/agenda/__init__.py
@@ -107,16 +107,12 @@ def next_uk_fathers_day(input_date: date) -> date:
     return fathers_day
 
 
-def timezone_transition(
-    start_dt: datetime, end_dt: datetime, key: str, tz_name: str
-) -> list[Event]:
-    """Clocks changes."""
+def get_next_timezone_transition(from_dt: datetime, tz_name: str) -> date:
+    """Datetime of the next time the clocks change."""
     tz = pytz.timezone(tz_name)
-    return [
-        Event(name=key, date=pytz.utc.localize(t).astimezone(tz))
-        for t in tz._utc_transition_times  # type: ignore
-        if start_dt <= t <= end_dt
-    ]
+    dt = next(t for t in tz._utc_transition_times if t > from_dt)
+
+    return typing.cast(date, dt.date())
 
 
 async def get_next_bank_holiday(input_date: date) -> list[Event]:
@@ -124,7 +120,7 @@ async def get_next_bank_holiday(input_date: date) -> list[Event]:
     url = "https://www.gov.uk/bank-holidays.json"
     filename = os.path.join(data_dir, "bank-holidays.json")
     mtime = os.path.getmtime(filename)
-    if (unixtime() - mtime) > 60 * 60 * 6:  # six hours
+    if (unixtime() - mtime) > 3600:  # one hour
         async with httpx.AsyncClient() as client:
             r = await client.get(url)
         open(filename, "w").write(r.text)
@@ -301,9 +297,6 @@ async def get_data(now: datetime) -> typing.Mapping[str, str | object]:
     last_year = today - timedelta(days=365)
     next_year = today + timedelta(days=365)
 
-    minus_365 = now - timedelta(days=365)
-    plus_365 = now + timedelta(days=365)
-
     (
         gbpusd,
         gwr_advance_tickets,
@@ -324,12 +317,8 @@ async def get_data(now: datetime) -> typing.Mapping[str, str | object]:
         "us_holiday": get_us_holidays(today),
         "next_us_presidential_election": next_us_presidential_election,
         "stock_markets": stock_markets(),
-        "uk_clock_change": timezone_transition(
-            minus_365, plus_365, "uk_clock_change", "Europe/London"
-        ),
-        "us_clock_change": timezone_transition(
-            minus_365, plus_365, "us_clock_change", "America/New_York"
-        ),
+        "uk_clock_change": get_next_timezone_transition(now, "Europe/London"),
+        "us_clock_change": get_next_timezone_transition(now, "America/New_York"),
         "mothers_day": next_uk_mothers_day(today),
         "fathers_day": next_uk_fathers_day(today),
         "uk_financial_year_end": uk_financial_year_end(today),