Climate is an important factor to consider when growing bulbs. By learning about the origin and natural conditions of a plant, you'll know whether you can provide a similar environment. Important factors include when it rains (summer or winter), how much it rains, how cold it gets in winter (when bulbs are dormant or growing), and whether winter dormant bulbs are protected under snow (a moderating influence). Summer temperatures are equally important, both day and night highs and lows. This wiki page features links to wiki pages with climate information. This page also includes links to PBS list discussions of bulbs that can be grown successfully in certain climates, areas, or special situations.
Hardiness Zone Maps shows cold and heat maps for various regions across the world.
Rainfall Graphs includes pdf files plotting the comparative rainfall patterns for a wide range of cities around the world, plus some temperature information.
Mediterranean Maps provides maps and information comparing mediterranean-climate areas around the world, where many bulbs originate. There's a special emphasis on summer rainfall and winter cold. The amount of summer rainfall a plant gets in its native climate will help to determine how much water it can tolerate in the garden, and the amount of winter cold it gets should determine how resistant it is to frost.
Books on gardening in dry climates
Several books stand out as good references on gardening in mediterranean and related climates. Although none of these are exclusively about bulbs, they are all useful references for bulb growers.
Plant Life in the World's Mediterranean Climates by Peter Dallman. The classic overview of plants in the world's mediterranean climates. Comparative maps and diagrams, and a lot of background information, but no gardening hints.
The Dry Gardening Handbook by Olivier Filippi. Has a very interesting section comparing the mediterranean climates, with a good explanation of how they differ, and a lot of gardening hints. Most of the book is an overview of mediterranean-climate plants, focusing mostly on plants from Europe, with very little specific material on bulbs.
High and Dry by Robert Nold. An excellent and very entertaining guide to gardening in cold, summer-dry climates (like mediterranean climates, but with colder winters). Although many bulbs come from this sort of climate, it has only a short chapter on bulbs.
Bulbs for various climates
Bulbs for continental climates (PBS discussion)
Bulbs for the Pacific Northwest Gardens (PBS discussion
Bulbs for Mediterranean gardens (PBS discussion)
Bulbs for Continental climates, Upper Midwest (PBS discussion)
Bulbs for Texas (PBS discussion)
Special situations
Growing tender bulbs in cold climates (PBS discussion thread)
Coping with cold; Bulbs for frozen soil (PBS discussion)
Bulbs with surprising hardiness (PBS discussion)