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Weather for 91739 — Rancho Cucamonga, CA

Conditions and forecast for the exact centre of ZIP code 91739 (34.170, -117.518), not a nearby airport.

65°

Clear sky

Feels like:
60°
Humidity:
44%
Wind:
18 mph
Dew point:
43°

Source updated: 1:55:54 PM · WeatherSignal checked: 1:55:54 PM

Source: Open-Meteo (national weather-service models)

Next 12 hours in 91739

2 PM

64°

0%

3 PM

66°

0%

4 PM

69°

0%

5 PM

72°

0%

6 PM

75°

0%

7 PM

77°

0%

8 PM

80°

0%

9 PM

81°

0%

10 PM

81°

0%

11 PM

80°

0%

12 AM

78°

0%

1 AM

74°

0%

7 day forecast for 91739

  • Today

    81° / 64°

    0% rain · 19 mph wind

  • Saturday, Oct 17

    81° / 65°

    0% rain · 15 mph wind

  • Sunday, Oct 18

    81° / 63°

    0% rain · 9 mph wind

  • Monday, Oct 19

    78° / 64°

    0% rain · 8 mph wind

  • Tuesday, Oct 20

    75° / 58°

    0% rain · 6 mph wind

  • Wednesday, Oct 21

    63° / 55°

    0% rain · 8 mph wind

  • Thursday, Oct 22

    62° / 51°

    0% rain · 3 mph wind

About ZIP code 91739

91739 covers Rancho Cucamonga in California. Forecasts on this page are generated for the coordinates at the centre of the ZIP code, so small differences from a nearby city forecast are expected and usually correct.

Closest cities with full forecast pages: Rancho Cucamonga (6 mi), Fontana (7 mi), Rialto (10 mi), Ontario (11 mi).

Nearby ZIP codes

Severe weather warnings are issued by the National Weather Service for counties and polygons that may not line up with ZIP code boundaries. Always follow official warnings for your exact address.

Planning your week in Rancho Cucamonga 91739, California

  • The warmest afternoon ahead is today, reaching about 81°F.
  • The coldest night ahead dips to about 51°F.
  • This is a dry stretch — most days show rain chances under 20%, good for outdoor plans.
  • The breeziest day looks like today, with sustained wind near 19 mph.
  • UV reaches 7 on the sunniest day — sunscreen is worth it if you will be outside around midday.

Common questions about Rancho Cucamonga 91739, California weather

How accurate is the Rancho Cucamonga 91739, California forecast?
The next 48 hours are usually reliable on temperature and sky cover, with timing that can shift by an hour or two. Days three and four are dependable for the overall pattern. Beyond that, treat the numbers as a planning direction rather than a promise — we label confidence on every day so you can judge for yourself.
What is the best day this week in Rancho Cucamonga 91739, California?
No day in the current outlook has a rain chance above 40%, so conditions look favorable for outdoor plans across the week.
Where does this forecast come from?
Forecast values come from national weather model data, and official warnings come from the National Weather Service. We show the source and the last-updated time on every page, and we never invent a number the source did not publish — missing measurements are hidden, not guessed.
How often is this page updated?
The forecast refreshes whenever the source model publishes new data, typically several times a day. The freshness note near the top of the page shows exactly when the numbers you are looking at were issued.

More weather for Rancho Cucamonga 91739, California

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