Average Winter Temps where I live:
November: High=53, Low=42
December: High=48, Low=38
January: High=47, Low=37
February: High=47, Low=36
March: High=52, Low=40
I have a 1.5 mile ride into school. I carry a backpack, which gets sweaty and tend to move quite fast. I tend to leave most mornings in jeans, t-shirt, hoodie, gloves and add a hat when it's below 35. Parents say I should be wearing a coat as well, and get uptight as I don't put on a jacket to leave the house. This seems silly to me, as by the afternoon ride home, even the hoodie can get quite sweaty. I do wear a very lightweight raincoat over the top for moderate/ heavy rain, but loathe to as I get too hot, so I skip it for drizzle/ light rain. I need the hoodie as some of the classrooms are chilly, and so prefer it over a coat. I also like to be in shorts if I know I'll have to ride home in over 55, unless it's <40 in the morning. I do dress better than that for my longer distance speed training rides. My normal dress code for that is:
>60=lycra shorts +cotton t shirt (I want my t shirt to be sweat soaked and so cool me off)
50-60=lycra shorts+poly shirt
40-50=lycra long trousers+poly shirt+gloves
30-40=lycra long trousers+poly shirt+raincoat+gloves+headband (to protect my ears)
20-30=lycra long trousers+poly shirt+raincoat+double up on socks and gloves+hat
The lowest temperature I have had to ride in ever is 21, so I don't have a range for that. In fact, i only find myself riding in under 30, a few time a month and since I do my speed training in the afternoon, it's usually at least in the 30's.
How does all this compare with what you're wearing. My mum goes crazy to find out I'm wearing only a short sleeved top and thin waterproof jacket on my torso on a 35 degree ride.