I've got a 15 mile one way commute, which means office clothes are right out.

Summer (i.e. temperatures >25C):
Cycling jersey and shorts. Fingerless gloves. Headband (if over 30). Cycling shoes with thin socks on the bike with clipless, sandals on the bike with double sided pedals.

Spring/Fall (i.e. temperatures 4-25C)
Cycling jersey and shorts. Nylon pants (neon green from the early 90s!) if it's cool (below 8C), thin breathable jacket with a light rain jacket over top if it's raining. Cycling shoes with normal socks, with neoprene socks if it's raining. Full length MTB gloves.

Winter: (i.e. temperatures <4C)
Fleece lined tights. Cycling Jersey. Fleece lined, breathable, highly water resistant cycling jacket. Water resistant, fleece lined gloves. Thin balaclava (not covering mouth or nose) if it's chilly (below 2C). Waterproof hiking boots and wool socks on the bike with double sided pedals. Cycling shoes with two layers of socks on the bike with clipless pedals.