Honestly, if you've ever spent a weekend in Portsmouth, you know the drill. One minute you're staring at the Spinnaker Tower under a crisp blue sky, and the next, a wall of grey mist rolls off the Solent and ruins your chips. It’s an island city—literally. Portsea Island is tucked behind the Isle of Wight, which creates this bizarre, micro-climatic bubble that makes the weather forecast in Portsmouth UK feel more like a game of chance than a science.
Right now, we're staring down a typical January stretch. It’s damp. It’s grey.
Current Vibes: The 24-Hour Reality
If you're heading out tonight, Friday, January 16, 2026, don’t leave the house without a decent shell. We're currently looking at light showers with a temperature of 43°F. But here’s the kicker: the wind is pulling in from the south at about 6 mph, which makes that air feel more like 39°F.
Humidity is sitting at a staggering 93%. Basically, the air is soup.
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Tomorrow, Saturday, January 17, isn't offering much of a reprieve. Expect a high of 48°F and a low of 43°F. There’s a 35% chance of rain during the day, tapering off to a mostly cloudy night. It’s that classic Portsmouth "not quite raining but you’re still getting wet" kind of vibe.
Why the Solent Changes Everything
Most people check the general UK forecast and assume it applies here. It doesn't.
Because we are low-lying—one of the lowest cities in the UK, actually—the relationship between the tide and the clouds is intimate. In March 2008, the tide hit 5.53 metres. That’s nearly 3 metres above sea level. When you get a heavy rain warning alongside a high spring tide, places like Clarence Parade don't just get puddles; they get flooded.
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The Isle of Wight acts like a massive windbreak for the south-westerly Atlantic waves, but it also creates a "double high water" effect. This means during a storm, the hydraulic pressure on our sea defences lasts way longer than it does in Southampton.
The 10-Day Outlook: What to Expect
Looking further ahead into late January 2026, the pattern remains stubbornly consistent.
- Sunday (Jan 18): High of 48°F, low of 44°F. Light rain is likely both day and night.
- Monday (Jan 19): A bit of a break. Cloudy during the day, with the sun potentially peeking through a partly cloudy sky at night. High 49°F.
- Tuesday (Jan 20): Back to light rain. High 48°F, low 46°F.
- Wednesday (Jan 21): Mostly cloudy. Humidity drops slightly to 76%, which might make the air feel a bit crisper.
By the time we hit next weekend, Friday, January 23, and Saturday, January 24, we might actually see some "partly sunny" intervals. Temperatures stay steady in the mid-40s. It’s not tropical, but after a week of light rain, we'll take it.
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The Bigger Picture: Is Portsmouth Getting Warmer?
Local data from the Portsmouth City Council and the East Solent Coastal Partnership shows a clear trend. Winters are getting wetter. Since 2000, there hasn't been a single year without an extreme weather event in the city.
We used to average about 50 days of frost a year across the UK. By 2026, that number is thinning out. While that sounds nice for your heating bill, it means more "high-impact" rain days. Instead of a light drizzle, we’re getting the kind of intense downpours that the Victorian drainage system in Southsea just wasn't built for.
Expert Advice for Navigating Portsmouth Weather
Don't trust the "feels like" temperature on your phone if you’re near the Hard or Southsea seafront. The wind chill off the water is significantly sharper than it is in the city centre.
Next Steps for Your Week:
If you're planning a trip to the historic dockyard or a walk along the ramparts, aim for Monday afternoon. It's the only day in the current ten-day stretch where the precipitation chance drops significantly enough to leave the umbrella in the car. For those on the water, keep a close eye on the "Chimet" recordings—the weather station about a mile out from Chichester Harbour. It gives a much more accurate reading of the Solent’s wind speed than any inland sensor will ever provide.