15-Day Weather Forecast - Cardiff

15-day weather forecast for Cardiff: temperatures from 5°C (41°F) to 21°C (70°F). Average daily high 17°C (63°F) over the next 15 days.

Hourly Forecast by Day

Today·11 Sep
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Temperature · peaks at +20°C

15-Day Temperature Trend

20°15°TodaySep20°13°Tmrw20°17°Sun21°17°Mon19°14°Tue17°12°Wed18°14°Thu16°12°Fri18°13°Sat16°9°Sun17°5°Mon19°12°Tue14°8°Wed12°6°Thu14°5°Fri
Colour scale for daily high temperature bars

15-Day Weather Forecast

Updated just now
  • Date
    High / Low
  • Fri, Sep 11Today
    +20°/+15°
    feels +19°0.5 mm · 82%15 km/hUV 3 · Low
    06:4119:36
  • Sat, Sep 12Tomorrow
    +20°/+13°
    feels +19°2.3 mm · 75%26 km/hUV 3 · Low
    06:4219:34
  • Sun, Sep 13Sun
    +20°/+17°
    feels +20°5.7 mm · 89%17 km/hUV 3 · Low
    06:4419:31
  • Mon, Sep 14Mon
    +21°/+17°
    feels +21°2.9 mm · 43%22 km/hUV 4 · Mod
    06:4519:29
  • Tue, Sep 15Tue
    +19°/+14°
    feels +18°0.4 mm · 39%22 km/hUV 4 · Mod
    06:4719:27
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  • Wed, Sep 16Wed
    +17°/+12°
    feels +15°0 mm · 18%17 km/hUV 4 · Mod
    06:4919:24
  • Thu, Sep 17Thu
    +18°/+14°
    feels +16°1.2 mm · 51%23 km/hUV 4 · Mod
    06:5019:22
  • Fri, Sep 18Fri
    +16°/+12°
    feels +13°0 mm · 18%23 km/hUV 4 · Mod
    06:5219:20
  • Sat, Sep 19Sat
    +18°/+13°
    feels +16°6.0 mm · 34%19 km/hUV 4 · Mod
    06:5319:18
  • Sun, Sep 20Sun
    +16°/+9°
    feels +14°0 mm · 24%15 km/hUV 4 · Mod
    06:5519:15
  • Mon, Sep 21Mon
    +17°/+5°
    feels +16°0.6 mm · 24%20 km/hUV 4 · Mod
    06:5719:13
  • Tue, Sep 22Tue
    +19°/+12°
    feels +16°3.0 mm · 25%30 km/hUV 4 · Mod
    06:5819:11
  • Wed, Sep 23Wed
    +14°/+8°
    feels +10°0 mm · 32%19 km/hUV 4 · Mod
    07:0019:09
  • Thu, Sep 24Thu
    +12°/+6°
    feels +8°0 mm · 29%21 km/hUV 4 · Mod
    07:0119:06
  • Fri, Sep 25Fri
    +14°/+5°
    feels +12°0 mm · 31%10 km/hUV 2 · Low
    07:0319:04

Weather Insight

Cardiff's 15-day outlook ranges from a low of 5°C to a high of 21°C, with an average daytime high near 18°C. Air quality is currently good (AQI 26), with no notable outdoor health concerns.

Today vs Normal

20°C+2° above normal

The long-term average high for today is 18°C.

23 of the last 28 days with published data ran above normal.

It continues that pattern - today's forecast is also running above normal.

2026-08-28: 20°C20°2026-08-29: 21°C21°2026-08-30: 20°C20°2026-08-31: 19°C19°2026-09-01: 20°C20°2026-09-02: 19°C19°2026-09-03: 21°C21°2026-09-04: 19°C19°2026-09-05: 19°C19°2026-09-06: 24°C24°2026-09-07: 18°C18°2026-09-08: 17°C17°

Red = above normal, blue = at or below · last 12 days

Air Quality

Air Quality
Good

Air quality is considered satisfactory, and air pollution poses little or no risk. It’s a good day to be active outside.

Extended Outlook for Cardiff

Over the next 15 days, Cardiff is forecast to see temperatures ranging from 4°C to 21°C, averaging a daily high of 18°C. The extended outlook indicates frequent showers on 9 out of 15 days. Conditions are suitable for most outdoor activities; carry an umbrella on days with showers.