15-Day Weather Forecast - St Johns

15-day weather forecast for St Johns: temperatures from 5°C (41°F) to 25°C (77°F). Average daily high 20°C (68°F) over the next 15 days.

Hourly Forecast by Day

Today·11 Sep
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Temperature · peaks at +18°C

15-Day Temperature Trend

18°7°TodaySep22°10°Tmrw23°11°Sun16°9°Mon14°7°Tue14°6°Wed17°5°Thu22°8°Fri25°12°Sat21°12°Sun22°12°Mon24°12°Tue21°11°Wed24°10°Thu21°9°Fri
Colour scale for daily high temperature bars

15-Day Weather Forecast

Updated just now
  • Date
    High / Low
  • Fri, Sep 11Today
    +18°/+7°
    feels +16°17 km/hUV 6 · Hi
    06:1918:02
  • Sat, Sep 12Tomorrow
    +22°/+10°
    feels +21°17 km/hUV 6 · Hi
    06:1818:03
  • Sun, Sep 13Sun
    +23°/+11°
    feels +19°0.4 mm · 56%31 km/hUV 6 · Hi
    06:1618:03
  • Mon, Sep 14Mon
    +16°/+9°
    feels +13°0.3 mm · 22%20 km/hUV 6 · Hi
    06:1518:04
  • Tue, Sep 15Tue
    +14°/+7°
    feels +10°0.7 mm · 27%18 km/hUV 6 · Hi
    06:1418:05
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  • Wed, Sep 16Wed
    +14°/+6°
    feels +11°20 km/hUV 6 · Hi
    06:1218:06
  • Thu, Sep 17Thu
    +17°/+5°
    feels +15°17 km/hUV 6 · Hi
    06:1118:06
  • Fri, Sep 18Fri
    +22°/+8°
    feels +21°12 km/hUV 7 · Hi
    06:0918:07
  • Sat, Sep 19Sat
    +25°/+12°
    feels +21°0 mm · 2%20 km/hUV 6 · Hi
    06:0818:08
  • Sun, Sep 20Sun
    +21°/+12°
    feels +21°0 mm · 10%14 km/hUV 7 · Hi
    06:0718:08
  • Mon, Sep 21Mon
    +22°/+12°
    feels +20°0 mm · 15%26 km/hUV 5 · Mod
    06:0518:09
  • Tue, Sep 22Tue
    +24°/+12°
    feels +25°0 mm · 8%25 km/hUV 7 · Hi
    06:0418:10
  • Wed, Sep 23Wed
    +21°/+11°
    feels +19°0 mm · 13%18 km/hUV 7 · Hi
    06:0218:11
  • Thu, Sep 24Thu
    +24°/+10°
    feels +22°0 mm · 14%18 km/hUV 3 · Mod
    06:0118:11
  • Fri, Sep 25Fri
    +21°/+9°
    feels +21°0 mm · 17%19 km/hUV 7 · Hi
    06:0018:12

Weather Insight

St Johns's 15-day outlook ranges from a low of 5°C to a high of 25°C, with an average daytime high near 20°C. That's 2° above the long-term average high of 18°C for this time of year. It continues a recent pattern — 15 of the last 19 days with published data have run warmer than normal. Air quality is currently good (AQI 27), with no notable outdoor health concerns.

Today vs Normal

18°C0° below normal

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

15 of the last 19 days with published data ran above normal.

That's a break from the pattern - today's forecast runs below normal even though the recent stretch mostly ran above.

2026-08-19: 18°C18°2026-08-20: 17°C17°2026-08-21: 16°C16°2026-08-22: 18°C18°2026-08-23: 20°C20°2026-08-24: 13°C13°2026-08-25: 16°C16°2026-08-26: 17°C17°2026-08-27: 19°C19°2026-08-28: 22°C22°2026-08-29: 22°C22°2026-08-30: 21°C21°

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 St Johns

Over the next 15 days, St Johns is forecast to see temperatures ranging from 5°C to 25°C, averaging a daily high of 20°C. The extended outlook indicates occasional showers on 3 days, with 1.4 mm total accumulation. Conditions are suitable for most outdoor activities; carry an umbrella on days with showers.