Is it raining now in Portsmouth?
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5 OctNo upcoming precipitation for the next hour.
Last updated: 20:00, 5 Oct 2026
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Rain in Portsmouth: What You Need to Know
Portsmouth is built on Portsea Island, surrounded by water on three sides, with Portsdown Hill rising behind the mainland shore. Rain crosses the Solent from the south-west with little to slow it, and the island's flat ground and seafront leave nowhere to shelter. That is where a Portsmouth rain radar helps most, since hyperlocal radar reads the live position of the rain instead of an area forecast.
Rain bands crossing the Channel are shaped by the sea, the South Downs and the Solent, which determine how each one breaks up on its way to the south coast. On warm days, sea-breeze convergence triggers thunderstorms along the coast and just inland, and a regional forecast averages those storms away rather than showing them. The Isle of Wight and Portsdown Hill split incoming bands, and the Solent's warm autumn water feeds heavier showers, so rain can soak Southsea while Cosham under the hill stays dry.
RainViewer draws the live rain radar for Portsmouth, England, from Met Office data, with real-time rain refreshed on every 5-minute radar update. The live map shows whether a shower is over the Isle of Wight, crossing the Solent or already at the Spinnaker Tower, which a forecast for Portsmouth cannot tell you.
Rain by Season in Portsmouth
Autumn and winter frontal season (October to January)
Atlantic depressions move along or across the Channel, and named storms bring strong winds and high seas along with heavy rain. Seafront roads, ferries and coastal paths feel it first, and rain on already-saturated ground raises the flood risk in low-lying areas. Named storms bring surge and spray to the Southsea seafront, and Storm Ciarán in November 2023 brought severe gales and heavy rain to this coast.
Transition months (February to April)
Spring showers and hail cross the Solent, and Southsea Common events and Isle of Wight crossings are the first plans to be caught. Fronts lose their strength and cold showers cross the coast, occasionally with hail. Narrow, quick-moving showers make forecasting difficult, and it is seafront events and spring outdoor plans that are most exposed.
Summer thunderstorm season (May to September)
Summer brings ferries, festivals on Southsea Common and a thunderstorm risk, and every outdoor plan depends on the cell track. Warm land and a cooler sea trigger sea-breeze storms, and thunderstorms from the continent can drift in. Beach days, festivals and air shows depend on the cell track, because a storm can be over the seafront within minutes.
Why You Need a Rain Radar in Portsmouth
Wightlink and Hovercraft passengers
Ferries to the Isle of Wight sail from Portsmouth Harbour and the Southsea hoverport, and passengers wait in the open. Check the radar for the shower's edge and time the walk to the terminal.
Historic Dockyard and Spinnaker Tower visitors
The Historic Dockyard and the Spinnaker Tower are mostly outdoors, and rain and wind cross the harbour quickly. See the next dry window on the radar and time the visit.
Great South Run and seafront runners
The Great South Run each October and everyday runners on the Southsea seafront run in the open. Watch the shower approach and time the run to the gap.
Commuters on the M275 and the Cosham corridor
The M275 into the city and the A27 past Cosham slow in heavy rain, and low ground floods after storms. Check the radar first and decide whether it is worth leaving now.
RainViewer Radar Coverage in Portsmouth
RainViewer shows UK precipitation using data from the Met Office, the national weather service, which runs a network of C-band dual-polarization weather radars. The Met Office network also feeds the European OPERA composite, and the RainViewer map refreshes with each new scan, about every 5 minutes. From Portsmouth the map also covers Southampton, Havant and Gosport.
Portsmouth Rain Radar: Frequently Asked Questions
- How does rain affect Isle of Wight ferries from Portsmouth?
Heavy rain and wind reduce visibility and roughen the Solent, and the terminal queues and open decks at Portsmouth Harbour feel it first. Passengers and crews watch the sky for the gap. RainViewer shows a shower crossing the Solent before it reaches the terminal.
- Does rain affect the M275 into Portsmouth?
Yes, heavy rain slows the M275 and the A27 at Cosham, and standing water collects on low stretches near the harbour. Check the radar before joining the road. RainViewer shows whether the cell is ahead of you.
- Does Portsmouth flood when it rains?
Yes, Portsea Island is low, and heavy rain with a high tide and a strong south-westerly wind can flood Southsea and Old Portsmouth. Coastal defences protect much of the shoreline. RainViewer shows whether a heavier band is on its way in advance.
- When is the best time to visit Portsmouth to avoid rain?
May to September is the best window to visit Portsmouth, with Southsea Common, the Historic Dockyard and the seafront at their best. Summer showers move through quickly. Check the radar early on and plan around whatever dry window it shows.
- Why can it rain on Southsea while Cosham stays dry around Portsmouth?
The Isle of Wight and Portsdown Hill split incoming bands, so Southsea on the open seafront can be soaked while Cosham, tucked under the hill on the mainland shore, stays dry. RainViewer draws each shower where it actually is, which is why a look at Southsea and Cosham can give different answers.
- How current is the rain shown on the Portsmouth radar map?
The rain shown on the Portsmouth radar map reflects the latest Met Office scan, which lands roughly every 5 minutes rather than on a fixed forecast schedule. Covering the south coast, Met Office C-band radar measures precipitation over both the Channel and the land, so a band approaching from the sea shows up before it reaches the shore. That currency is what makes the hyperlocal picture worth checking before heading out.
- What can I do with RainViewer in Portsmouth beyond checking current rain?
Set a rain alert on the Spinnaker Tower or Portsmouth Harbour station and RainViewer warns you before rain arrives. That lets you time a ferry or a visit. The 2-hour forecast in 5-minute slices shows the next gap, and saved locations track Southsea Common and the Dockyard together.
Track Rain in Portsmouth in Real Time
The Isle of Wight ferry queue and a walk along Southsea seafront both depend on a dry gap, and RainViewer shows the next one.
Showers off the sea reach Portsmouth with little notice, so timing matters more than the daily total.
The forecast says showers in Portsmouth this afternoon. RainViewer's live hyperlocal radar shows the cell over the Isle of Wight with the Spinnaker Tower still dry, which decides whether the ferry walk starts now.
Track rain in Portsmouth — free Upgrade to Essential for alerts, forecasts, and full radar history
2-hour forecast in 5-minute slices
The 5-minute steps show whether the walk along Southsea seafront fits inside the dry gap.
Rain alerts before arrival
Set the alert at Portsmouth Harbour station, and the warning arrives in time to decide whether to wait inside or walk to the ferry.
Direction arrows on the map
Storms usually arrive from the south-west, up the English Channel over Portsmouth, and the arrows show which way each cell is moving.
48 hours of radar history
Check the Solent and the seafront in the last 48 hours to see how much rain came down.
Multiple locations
Keep Portsmouth Harbour, Southsea Common and the Spinnaker Tower on the same list, each with its own alert.
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