What's on in London in spring, and what to book early

Chelsea Flower Show tickets go fast and the members' days go first, so sort those before anything else. Spring is when London heads back outdoors, with longer days, fuller parks and the big annual events arriving in turn, from the Marathon in April to Chelsea in May and London Open Gardens in early June. April averages a high of about 14°C with cold nights, and March is one of London's drier months, with rain on about nine days, so pack layers rather than a heavy coat, plus something waterproof for April.

The big three: Marathon, Chelsea and Open Gardens

The London Marathon is usually on a Sunday in late April, running from Greenwich to The Mall. Even if you're not running it's one of the best free days out in the city, with huge, cheerful crowds along the Embankment and around St James's Park. Roads close across central and east London for most of the day, so plan airport runs and restaurant bookings around it.

The RHS Chelsea Flower Show takes over the grounds of the Royal Hospital in Chelsea for a week in late May. Tickets are advance only, so buy the moment they're released, and consider the evening sessions, which are calmer and better for photos. All week the streets around Sloane Square are full of floral shop fronts that cost nothing to look at.

London Open Gardens, run by the London Gardens Trust over a weekend in early June, opens private and community gardens across the city that are normally shut, and one ticket gets you into dozens of them. It's an odd, lovely way to see the backs of Georgian squares and roof gardens you'd never know were there.

Markets, parks and a day with children

If you have a kitchen, spring is the season for farmers' markets. South Kensington's on Bute Street and Pimlico Road's on Orange Square both run on Saturday mornings, Notting Hill's is on Saturdays at Fox Primary School, and Marylebone's is on Sunday mornings at the Cramer Street car park. Look out for wild garlic, asparagus from late April and the first English strawberries by late May. Borough Market by London Bridge is open most days and made for a long grazing lunch, as long as you avoid Saturday, when it's heaving.

For children, the best spring events are free. The Royal Parks do the daffodils and blossom first, and Hyde Park, Regent's Park and St James's Park are all at their best from late March. Regent's Park has London Zoo on its northern edge, and the canal towpath that runs past it makes a good walk to Little Venice.

London weather by month

July is the warmest month, averaging 23°C by day. July has the fewest wet days (9) and October the most rain (80 mm). For sightseeing on foot, June scores best on our combined warmth-and-dryness measure.

Month	Avg high	Avg low	Rain	Wet days	Chance a 7-day stay sees a washout	Record high / low
January	8°C	2°C	74 mm	13	53%	16°C / -12°C
February	8°C	2°C	51 mm	10	43%	18°C / -8°C
March	11°C	4°C	45 mm	9	44%	23°C / -7°C
April	14°C	5°C	54 mm	10	44%	26°C / -3°C
May	17°C	8°C	54 mm	9	39%	30°C / -1°C
June	20°C	11°C	58 mm	9	35%	34°C / 2°C
July	23°C	13°C	52 mm	9	34%	34°C / 4°C
August	22°C	13°C	68 mm	9	37%	37°C / 4°C
September	19°C	11°C	62 mm	9	39%	29°C / 2°C
October	15°C	8°C	80 mm	11	47%	27°C / -2°C
November	11°C	5°C	76 mm	12	52%	18°C / -6°C
December	8°C	2°C	69 mm	12	50%	16°C / -8°C

Calculated NOAA GHCN-Daily observations at the Hampstead weather station, north London (records 1960–2015; averages from about 25 years per month). A wet day has 1 mm of rain or more.