Cam's right -- Cornell is the best comprehensive source, but should you want more "primary source" material, see two other threads at this site:
NGA Sailing Directions, URLs for direct downloads (General Interest Forums - Cruising)
and another one near that one from which you can download NGA Pilot
Charts.
Type "NGA Pilot
Charts" in the search engine and then download the pilot chart for the month you might consider the crossing. Pilot
charts have a wealth of info about weather, winds, currents, etc all in easy to read graphic form.
Conventional wisdom says the following:
1. North America to Europe via northern route -- summer (late May to August)
2. Europe to Caribbean -- late fall/winter via the trade wind route (Gibraltar to Canaries in September / October and Canaries to the Caribbean in late fall/winter. The ARC leaves the Canaries in late November, but you can cross anytime from then until the late spring provided you're out of the Caribbean hurricane box by June).
3. Pacific crossings from Mexico are dictated by the No. Pac. hurricane season, which generally coincides w/ the Atlantic hurricane season. You wouldn't leave Mexico before November and no later than April to be clear of the hurricane box by May 1st. You also need to consider the So. Pac tropical storm season -- you shouldn't arrive in Fr. Polynesia before late March/April and must be out of the tropics south of the Equator by November.