Las Vegas has a Mexican Monsoon season from Mid-July to Mid-September. However, rainfall for the year is only 4 1/2 inches and our monsoon season only averages about 1.2 inches. Unless you really need to protect your hair-do, don’t pack anything for rain—gamble on sunny, dry weather.
In a typical year it will be sunny about 308 days. Even in the least sunny months, expect about a 77% chance of sun and most of the cloudy days will have no rain. Priceline.com is the only travel site that guarantees against a rained out vacation but they require at least 1/2 inch of rain per day with booking no later than September 12, 2008 for travel occurring from August 16, 2008 to Novermber 16, 2008.
For example, if staying 7 days, you would need 4 days of half inch or more rain each day. This means 40% of an average full year of rainfall for Vegas would have to rain on your vacation to get a refund.
