Like in the rest of the UK, it's not exactly easy to predict the weather in Cambridge. Winters are generally cold (colder than London and the west country, but not usually as cold as parts of the north) and it can get very windy. Most years there's some snow around January / February, which is when the temperature is lowest. It doesn't rain as often as it does in most of the country - something to do with wet weather coming in from the west and having 'rained itself out' before it gets as far as East Anglia! Autumn and Spring are entirely unpredictable, and summer varies quite a lot as well. But there's usually a reasonable amount of sunshine by the end of May and sometimes it can be very pleasantly warm around that time. But obviously, nothing's guaranteed, and layers are the key!

The first thing to decide is whether you want to go there when the students are there or not. The undergraduates (with the possible exception of the final year students) are generally only around during term time. Terms are roughly as follows: 'Michaelmas Term' - start of Oct to start of Dec; 'Lent Term' - mid Jan to mid-March; 'Easter Term' - mid/end of Apr to mid/end of June. The graduate students generally stay around. It's noticeably quieter during December and over the first part of the Easter break, but after that, even when the students aren't around it's pretty busy with tourists, especially at weekends and on bank holidays.

Cambridge in winter can actually be absolutely gorgeous, particularly in the early mornings if there's been a heavy frost and clear skies. But it IS cold and in winter you wouldn't want to be sitting in a punt on the river, which is arguably one of the highlights! The city starts getting really touristy around Easter, generally, although of course there are tourists all year round. You definitely need a nice day to enjoy Cambridge properly - and all the photo opportunities look so much better in the sunshine. If it's warm you can have a picnic lunch by the river or sit outside at one of the many pubs.

More specific things that you might want to take into account relate to the university timetable. Between the start of Easter term and around the middle of June is "the exam period". This means stressed-out revising students. It also means that many of the colleges are closed or partially-closed to visitors to allow students to work in peace - many college buildings are student accommodation. Generally the larger colleges - those which charge for entry, such as King's, Trinity and St John's - stay mostly open unless there are actual exams going on, but the smaller ones are often closed for most of that period. If colleges are open, they will most likely have 'quiet please' signs posted at various points, especially outside libraries - sound really carries in courtyards and the older buildings won't have double glazing!

Then, dates change slightly every year, but at the end of the exam period comes 'May Week' (which is in June, usually about the middle, but don't let that worry you!). The first Sunday after everyone's finished their exams is known as 'Suicide Sunday', basically because most of the students get very, very drunk. It's probably quite an amusing spectacle for tourists, but then again, lots of colleges have garden parties and the like on that day, so again, they might be closed. It's also usually a slightly perilous day to be on the river, as lots of students hire out punts and go drinking and try to push each other in, etc. It's quite a laugh, but it's worth being warned in advance! Then during that week various colleges have May Balls (yes, in June) - Trinity's is particularly famous. This again involves colleges being closed during the day of the ball to set up and the day after to clear up, usually. It's great seeing people queueing for the balls in the early evening, you usually get to see some pretty spectacular dresses, and there are often fireworks displays in the evenings that can be seen from the river or other places in Cambridge.  And then towards the end of June there is a day or two of graduation ceremonies, which involves the graduating students walking to the Senate House, near King's Chapel, wearing academic gowns with hoods of various sorts depending on what sort of degree they're getting.

None of that means you absolutely shouldn't visit Cambridge at those times - you can always get a punt down the river, you can always see the colleges from the outside at the very least, and it's still a lovely town. It's just a warning not to be too disappointed if you go at that time of year and find a few colleges aren't open to visitors.

Here is the link to:  Cambridge Weather : Five Day Forecast