Common summer visitor and passage migrant, with records of overwintering. 

The Chiffchaff is the earliest of our returning migrants, usually arriving during the middle of March. The earliest spring arrival date for Stevenage is 7 March 2025 at Fairlands Valley Park, the latest autumn date is 23 November 2023 at Fairlands Valley Lakes.

Chiffchaffs winter further north than other related species, wintering in the Mediterranean and northern Africa. A small number also winter in Britain, including in Hertfordshire, these are probably birds from the Continent. Winter records for Stevenage are: One at Shephall Way on 2 February 1975; one in November and December 1988; one in a Jackdaw Close garden on 6 February 2000; one in a Jackdaw Close garden on 24 and 26 December 2001; one at Fairlands Valley Lakes in January 2005; one at Great Ashby on 24 February 2008; one in a garden on 8 January 2009; one in the London Road, near the Stevenage Brook on 2 December 2009; one at Burghley Close on 28 February 2016; one at Fairlands Valley Lakes on 21 December 2019.

Breeding was confirmed from six of Stevenage’s tetrads in the 1973 Breeding Atlas, ten in the 1992 Atlas and, from two in the 2012 Atlas.

In 2018 a juvenile was recorded in Fairlands Valley Park and fledged young were seen there on 15 June 2025.

The Common Bird Census at Watery Grove recorded them holding between one and seven breeding territories annually between 1972 and 1999 with, the exception of 1984 and 1991 when only their presence was recorded.

Most recorded in one location are, 12 in Box Wood on 1 September 1965, 12 at Watery Grove on 9 April 2008 and, 20 heard calling in Box and Pryors Woods on 4 April 1981.

Nine were ringed in Box Wood in 1978.

One of the sub-species, Siberian Chiffchaff (P.c.tristis) was heard and seen along the River Beane, Aston End on 20 December 2020.