Here's a selection of sites I use for weather and conditions across the Alps:

Weather

• Weather forecast for Chamonix - bear in mind that the translation can omit crucial details so, if you can, read the French version
• Weather forecast for Switzerland in general
• Weather forecast for the Valais from La Nouvelliste, a local paper published in Sion
• Weather forecast for the Val d'Aosta
• Synoptic chart for Europe, to give an overall picture of what's going on.

Avalanche Reports

• Avalanche Report for Haute Savoie
• Avalanche Report for Savoie
• Avalanche Report for Valais

Climbing Reports

• Office de Haute Montagne in Chamonix for local alpine activity
• SNGM (French Guides association) for both skiing and climbing activity

Webcams

• Webcam from my balcony, looking directly at the Aiguille du Midi!
• Compagnie du Mont Blanc, showing the different ski areas in the Chamonix valley
• Selection of Valais Webcams
• View of the Matterhorn, courstesy of the Hotel Bahnhof
• Val d'Aosta webcam gallery to check what life on the other side of the hill is like...