May, June and September. May and June give 15 to 17 hours of light on flat ground, the floodplain meadows the first half crosses are at their best, and the river is dry underfoot from Kemble to the Barrier. September is the same firm ground with the crowds gone and nearly thirteen hours of light, and it is the easiest of the three for getting a bed. April is worth adding for one reason: the fritillaries at North Meadow, Cricklade, peak in the last week.
This is a low, flat, year-round trail that never closes, and the seasonal constraint is water rather than weather. National Trails' own advice is that the best months are spring to the end of autumn, because in winter the Thames is prone to flooding, particularly upstream of Oxford, where the path crosses water meadows that hold standing water for weeks and where Natural England records the Cricklade meadows flooding in winter and more often in spring, chest deep at the southern edge. The two halves of the trail have different seasons: from Teddington down the surface is made up or paved and works in any month, while from the source to Oxford the walking season is roughly March to October and depends on the preceding fortnight's rain. One operational fact changes with the season rather than the weather, the Shepperton to Weybridge ferry, which runs daily March to October and weekends only from November to February, with a road route north to Walton Bridge when it is not running. The other seasonal service is baggage transfer, and it applies to the whole length rather than to the flood-prone third: the only operator publishing terms runs an April to October season, stating it as 1 April on one of its two sites and Easter Monday on the other, and the second operator publishes no season at all, so November to March is a full-pack walk unless you have confirmed otherwise. Because a station is within reach of almost every stage, a wet winter here means a shortened day rather than an abandoned trip.
Month-by-month guide
January
Poor
The month the upper river is least likely to let you plan. National Trails' own advice is that the Thames is prone to flooding in winter, particularly upstream of Oxford, and eight and a half hours of light leaves little room to walk round a problem you find at 2pm.
8.0 (Oxford) to 8.4 (Heathrow)°C high · 2.4 to 2.7°C low · ~8.4 hrs (sunrise ~08:03, sunset ~16:26 GMT at Oxford)Watch for: Floodwater across a meadow hides where the bank ends. The trail's own advice is not to walk into it, and it is the one piece of Thames Path safety advice that is specific rather than generic.
February
Mixed
Light is back to ten hours, which is enough for a 20 km day, and February is one of the drier months on the rainfall record. What it is not is dry underfoot, because the ground upstream of Oxford is carrying four months of rain.
8.6 to 9.0°C high · 2.3 to 2.6°C low · ~10.1 hrs (sunrise ~07:17, sunset ~17:21 GMT at Oxford)
March
Mixed
The driest month of the year on the rainfall record and the point at which the trail starts working end to end again. Whether it is a good month is decided by the preceding winter rather than by March itself.
11.3 to 11.7°C high · 3.6 to 4.1°C low · ~11.9 hrs (sunrise ~06:17, sunset ~18:11 GMT at Oxford, an hour later once the clocks change at the end of the month)
April
Good
Fourteen hours of light, ground that is usually walkable again, and the one week of the year the upper river has something you cannot see anywhere else. Birds are at their most active and visible in April and May while establishing territories.
14.4 to 15.0°C high · 5.3 to 6.0°C low · ~13.9 hrs (sunrise ~06:07, sunset ~20:04 BST at Oxford)
May
Excellent
Nearly sixteen hours of light on a flat trail, which means a 30 km day is a matter of appetite rather than logistics, and the meadows the route spends its first half crossing are at their best.
17.7 to 18.4°C high · 8.2 to 9.1°C low · ~15.7 hrs (sunrise ~05:10, sunset ~20:53 BST at Oxford)Watch for: Cattle are back in the riverside meadows, with calves. The route crosses grazed common land in several places, Cock Marsh above Cookham and Petersham Meadows below Richmond among them.
June
Excellent
The longest light of the year and the driest the upper meadows get. On a trail with a station near almost every stage this is the month where an unplanned extra 10 km costs nothing.
20.7 to 21.6°C high · 11.1 to 12.0°C low · ~16.7 hrs (sunrise ~04:44, sunset ~21:27 BST at Oxford)Watch for: Shade is scarce between Cricklade and Newbridge, and that is also the stretch with the longest run between shops.
July
Good
Hot, dry and busy. The walking is easy and the light is long, and the two things that make July harder than June are heat on an unshaded upper river and the first week, when the regatta has the Henley reach.
23.1 to 23.9°C high · 13.1 to 14.2°C low · ~16.3 hrs (sunrise ~05:02, sunset ~21:20 BST at Oxford)Watch for: The source itself is dry for much of the year and especially in summer, and the bed stays without water for some distance below it, so do not plan the first morning around finding water at the start.
August
Good
Warm, still long-lit, and the wettest of the summer months on the record, which mostly shows up as heavy showers rather than as ground you notice. The river towns are at their peak trade, so everything is open and everything is booked.
22.5 to 23.4°C high · 13.0 to 14.1°C low · ~14.7 hrs (sunrise ~05:48, sunset ~20:31 BST at Oxford)Watch for: Heat and water again on the shopless run between Cricklade and Newbridge.
September
Excellent
Summer ground with the summer crowds gone, and still nearly thirteen hours of light, which is enough for the 24 km days that make this a two-week trail. Beds are easier to get than at any point since April.
19.4 to 20.2°C high · 10.7 to 11.6°C low · ~12.7 hrs (sunrise ~06:38, sunset ~19:22 BST at Oxford)
October
Mixed
The wettest month on the record at both ends of the trail, and the month the ground goes back. Still perfectly walkable, but this is where the upper river stops being a summer path and starts being a winter one.
15.1 to 15.8°C high · 8.0 to 8.8°C low · ~10.8 hrs (sunrise ~07:28, sunset ~18:14 BST at Oxford, an hour earlier once the clocks change at the end of the month)
November
Poor
Nine hours of light, the second wettest month, and the point in the year when rain starts falling on ground that is already full. Flood alerts on the Thames and its tributaries are a November and December staple in the trail's own news feed.
10.9 to 11.5°C high · 4.9 to 5.3°C low · ~8.9 hrs (sunrise ~07:22, sunset ~16:17 GMT at Oxford)
December
Poor
Under eight hours of usable light, which caps a day at about 20 km on the half of the trail that has the fewest places to stop, and the river is at its least predictable.
8.2 to 8.8°C high · 2.6 to 3.1°C low · ~7.9 hrs (sunrise ~08:03, sunset ~15:57 GMT at Oxford)Watch for: Sunset before 16:00 means a stage that starts late finishes in the dark, and the upper river has no lit path and few road crossings to bail out at.
Sources and research notes · 20 sources
metoffice.gov.ukMet Office Oxford station (lat 51.761, lon -1.262, 63 m amsl). Monthly mean daily maximum, mean daily minimum and rainfall for every month 1991 to 2020, averaged over the full 30 years to give the temp high c, temp low c and rain mm figures for the upper and middle Thames.Checked 30 Jul 2026
metoffice.gov.ukMet Office Heathrow station (lat 51.479, lon -0.449, 25 m amsl), averaged 1991 to 2020 for the London end of the same fields. The gradient along the trail is small: Heathrow runs 0.4 to 0.9 C warmer by day than Oxford and about 100 mm drier over the year, which is why the climate fields are given as a two-station range rather than one average.Checked 30 Jul 2026
metoffice.gov.ukHadUK-Grid areal series, days per month with 1 mm or more of precipitation for England SE and Central S, averaged 1991 to 2020 for the rain days field. The region covers Oxford, Reading and London; the Cotswold source end sits in the SW and S Wales region, which runs about three wet days a month higher.Checked 30 Jul 2026
metoffice.gov.ukBraemar 1991 to 2020 monthly mean daily maximum, used only for the winter appeal comparison: March at Braemar averages 7.2 C by day, below a Thames January.Checked 30 Jul 2026
api.sunrise-sunset.orgMid-January sunrise, sunset and day length at Oxford, the trail's central latitude. All twelve months were fetched the same way and converted to local clock time (GMT, or BST from the end of March to the end of October).Checked 30 Jul 2026
api.sunrise-sunset.orgMid-June daylight anchor, 16.7 hours, paired with the December value of 7.9 hours to set the daylight range used in best months, avoid months and winter appeal.Checked 30 Jul 2026
api.sunrise-sunset.orgMid-December daylight, 7.9 hours with sunset at 15:57 GMT, used for the December rating and watch for.Checked 30 Jul 2026
nationaltrail.co.ukThe official seasonal advice: best months, winter flooding upstream of Oxford, waterlogged water meadows, the instruction not to walk into floodwater, churned mud at gates and where cattle gather, the wildlife months used in the flora fields, Environment Agency water taps at some locks, and the advice to book in advance.Checked 30 Jul 2026
nationaltrail.co.ukSection by section detail behind several month fields: the dry source and dry river bed in summer, North Meadow fritillaries in late April, blackberries in the hedges in late August and September on the Lechlade to Newbridge stretch, Cliveden's autumn colour in November, and the choice of routes at Shepperton Lock depending on whether the ferry is running.Checked 30 Jul 2026
nationaltrail.co.ukThat flood alerts on the Thames and its tributaries are a recurring autumn and winter item rather than a one-off, that low-lying sections and boardwalks are affected first, and that resurfacing at Streatley and the Abingdon boardwalk were done to cope with flooding and mud.Checked 30 Jul 2026
gov.ukNatural England on North Meadow, Cricklade, which the trail skirts: Britain's largest snake's-head fritillary population, and the seasonal flooding depth used in the April ground field and the season summary. Also that livestock graze the meadow.Checked 30 Jul 2026
bbowt.org.ukThe second fritillary site, on the Thames 1.5 miles south of Oxford city centre and on the route, flowering in April, and that it is wet underfoot all year.Checked 30 Jul 2026
theferrypoint.comThe one seasonal service pattern on the route: the Nauticalia ferry between Shepperton and Weybridge runs daily March to October and weekends only November to February, subject to weather and river conditions. Stored as a pattern only; no times or fares are recorded here.Checked 30 Jul 2026
gov.ukEnvironment Agency drinking water taps at locks along the non-tidal river, described as being for portable containers, and that lock keeper attendance is shorter in winter than in midsummer. Used for the July services field.Checked 30 Jul 2026
gov.ukThat the Environment Agency runs a stream warning board system on the reaches from Lechlade to Teddington, and its warning that flows can rise even in summer. Supports treating high water as a river-state question rather than a calendar one.Checked 30 Jul 2026
en.wikipedia.orgThe timing pattern of the regatta used in booking pressure and the June and July crowds fields. Used as a secondary source because the regatta's own site was returning a server error when checked.Checked 30 Jul 2026
readingandleedsfestival.comThat the Reading festival occupies a late August weekend, used for the August crowds field and booking pressure. The specific dates shown on the page are deliberately not stored.Checked 30 Jul 2026
walkthethames.co.ukthe operator's stated season of 1 April to the end of OctoberChecked 30 Jul 2026
walking.holidaythe same operator's other stated season, Easter Monday to the end of OctoberChecked 30 Jul 2026
movemybags.comthat the second operator publishes no season at all, so nothing is assumed for itChecked 30 Jul 2026