What I've done is look at the forecasts and compared them to
each other. I haven't correlated whether the weather they
forecast actually happened, just how often the forecasts changed
(since a 5 day forecast that changes the very next day can't
be relied on, so isn't any use).

February followed the pattern of January with more changes to the
forecasts and consequently even lower hit rates - although
this tends to be due to the detail (i.e. just _how_ rainy or
cloudy) of the weather rather than the type (cloud/sun/rain). So
if the different types are consolidated into simple cloud, wet,
sun then the next day forecast accuracy is above 75% and quite
good up to 3 days.
So, although the headline numbers make the forecast accuracy look
fairly poor, there aren't really any instances where the day-0
forecast was drastically different from the previous days' - so
there weren't actually any major surprises.

forecast forecast on: times num of days
-- date -- on day D-1 D-2 D-3 D-4 correct changes ahead
Sun 30 Jan WC WC WC D GC 2 2 2
Mon 31 Jan WC* SI GC WC GC 1 4 0
Tue 1 Feb WC* WC WC HR WC 3 2 2
Wed 2 Feb M WC WC M WC 1 3 0
Thu 3 Feb S S S SI SI 2 1 2
Fri 4 Feb WC GC D WC LRS 1 4 0
Sat 5 Feb WC* GC LR LR WC 1 3 0
Sun 6 Feb WC* WC WC LR HR 2 2 2
Mon 7 Feb WC* GC LR LR LR 0 2 0 !
Tue 8 Feb S M F S S 2 3 0
Wed 9 Feb WC SI LR LR WC 1 3 0
Thu 10 Feb HR LR HR HR WC 2 3 0
Fri 11 Feb F WC LR WC SI 0 4 0 !
Sat 12 Feb SI SI S SI SI 3 2 1
Sun 13 Feb HR HR HR HR LR 3 1 3
Mon 14 Feb S SI HR SI SI 0 3 0 !
Tue 15 Feb HR HR HR LR SI 2 2 2
Wed 16 Feb SI WC WC LRS LRS 0 2 0 !
Thu 17 Feb WC SI SI SI WC 1 2 0
Fri 18 Feb WC* GC WC WC SI 2 3 0
Sat 19 Feb D LR HR HRS HRS 0 3 0 !
Sun 20 Feb WC WC M WC HRS 2 3 1
Mon 21 Feb LR LR WC HR HRS 1 3 1
Tue 22 Feb GC WC WC LR WC 0 3 0 !
Wed 23 Feb LR D HR HR LR 1 3 0
Thu 24 Feb S S WC S WC 2 3 1
Fri 25 Feb WC M WC WC WC 3 2 0
Sat 26 Feb LR LRS WC LRS LRS 0 3 0 !
Sun 27 Feb LRS SI SI SI LRS 1 2 0
Mon 28 Feb LR WC LR WC SI 1 4 0

For last 30 days: avg 2.67 different forecasts per day
On average forecasted 0.57 days ahead
Correct 4 days ahead: 0 times
Correct 3 days ahead: 1 times
Correct 2 days ahead: 6 times
Correct 1 day ahead: 10 times (33.3%)
Number of times the weather was same as yesterday(*): 6 times (20.0%)
Number of days every forecast was wrong(!): 7 times (23.3%)

Key:
D: Drizzle 1 occurrences, predicted 3 times about right
F: Fog 1 occurrences, predicted 1 times under-forecast
GC: Grey Cloud 1 occurrences, predicted 7 times over-forecast
HR: Heavy Rain 3 occurrences, predicted 14 times about right
HRS: Heavy Rain Shower 0 occurrences, predicted 4 times over-forecast
LR: Light Rain 4 occurrences, predicted 17 times about right
LRS: Light Rain Shower 1 occurrences, predicted 7 times over-forecast
M: Mist 1 occurrences, predicted 4 times about right
S: Sunny 4 occurrences, predicted 7 times under-forecast
SI: Sunny Intervals 2 occurrences, predicted 20 times over-forecast
WC: White Cloud 12 occurrences, predicted 36 times about right