Southampton Weather Month by Month

Southampton is a wet, mild, maritime city with no dry season and no extreme one. What the weather decides here is not whether you go out but what you take with you, and how far west you are willing to drive. Figures below are Met Office 1991–2020 normals for Southampton, Mayflower Park. If your date is fixed, an Southampton to Stonehenge tours that keeps you in a vehicle between stops is worth more in November than in July.

What the weather does to a visit here

Rain is the constraint, not cold. The city averages 819 mm across about 120 days a year with a millimetre or more, and there is no month with less than 44 mm. That does not stop anything — both walking tours state that they run rain or shine — but it does decide whether a two-hour walk is the right way to spend your only afternoon ashore.

The second thing it decides is how far west you go. Stonehenge is forty miles out on open chalk downland with no shelter at all, and it is reliably colder and windier there than at the quayside. A day that reads as mild in Southampton reads as raw at the stones, which is why the private cars that let you sit out a shower are worth more in winter than the arithmetic suggests.

Southampton month by month

January

The coldest month, averaging 8.8°C by day and 3.2°C at night, with about seven days of air frost. Sunshine is at its lowest of the year after December at 63 hours. Very few ships turn round here now, so the old town is as quiet as it gets and the museums have room in them.

February

Barely warmer by day at 9.1°C and marginally colder at night. Rainfall drops to 64 mm, the lowest of the winter, and sunshine climbs to 83 hours. A walking tour is comfortable in a coat; Stonehenge on open downland is not.

March

The first real turn: 11.5°C by day, 125 hours of sun and 56 mm of rain. Frost drops to under three days in the month. Stonehenge switches to its summer hours in the last week, closing at 6pm rather than 5pm.

April

14.7°C by day, 182 hours of sun and 52 mm of rain across nine and a half wet days. The cruise season is building and the coaches start filling. Long enough evenings that a late tour still returns you in daylight.

May

18.0°C by day and the driest month of the year at 47 mm, with 215 hours of sun and no air frost at all. The Cotswolds and Oxford day is at its best now. Book the small-group coaches early, because May is when they start selling out.

June

20.6°C by day, 212 hours of sun and a slight rise in rain to 57 mm. The longest days of the year, which matters if your ship sails in the evening and you want a full afternoon ashore. Turnaround Saturdays are now busy.

July

The warmest month at 22.6°C, the sunniest at 224 hours and the driest by rainfall at 44 mm. It is also the fullest month in the port. Everything here is bookable and almost nothing is quiet.

August

22.5°C by day and the warmest nights of the year at 14.0°C, with 206 hours of sun and 59 mm of rain. School holidays put pressure on the museums and on Stonehenge time slots. Book the entry ticket well ahead if your tour does not include it.

September

20.1°C by day and sunshine dropping sharply to 152 hours. Rain edges up to 60 mm. Stonehenge returns to winter hours on the 7th, closing at 5pm with last entry at 3pm, which shortens the useful end of an afternoon tour.

October

15.9°C by day and the second wettest month at 93 mm across nearly twelve wet days. Sunshine falls to 113 hours. This is when a coat stops being optional and when the two indoor museums start earning their admission.

November

The wettest month of the year at 100 mm, with 12.8 days of rain and only 76 hours of sun. Days average 12.0°C. The cruise season is winding down and the private cars become easier to book at short notice.

December

9.3°C by day, the least sunshine of any month at 55 hours, and 97 mm of rain over nearly thirteen days. Almost seven days of air frost. Three transfer operators quote separate holiday prices for the 24th to the 26th and the 31st.

The seasons, and which one you want

Spring, March to May. The best value of the year. Rainfall falls month on month to a low of 47 mm in May, sunshine climbs from 125 to 215 hours, and the port is busy without being full. Stonehenge moves to summer hours at the end of March.

Summer, June to August. Warmest, sunniest and busiest. Highs of 20.6 to 22.6°C and 206 to 224 hours of sun a month. Book the entry tickets and the small-group coaches earlier than you think you need to.

Autumn and winter, September to February. Sunshine roughly halves between September and November and rainfall peaks at 100 mm. Days average 8.8 to 15.9°C. Fewer ships, quieter museums, and the season in which an indoor plan and a warm vehicle stop being optional.

Best time of day

For the city, the morning. Both walking tours run at 10am and the light on the old town's western wall is best before the middle of the day, when it faces the water. The museums are quietest in the first hour after they open at ten.

For Stonehenge, as early as your tour allows. Reviewers on two of the private transfers describe arriving as the site opened and having it comparatively quiet, and the coach parties from London do not reach the plain until later. Last entry is 4pm in summer and 3pm the rest of the year, so an afternoon start is tighter than it looks.

Frequently asked questions