You might want to know in which months of the year Hawaii gets the most rainfall before you book your vacation. Or learn how the average temperature has changed in your city over the past few decades. Whatever your reason for finding out past weather history, you have a few different tools at your disposal, all easily accessible online.

Climate Data Online gives you free access to the National Oceanic and Atmospheric Administration's archive of worldwide historical weather and climate data. On the home page, click on "Search Tool," and then select from the dropdown box to choose your weather observation type (such as Daily Summaries, Global Summary of the Month and Precipitation Hourly). Use the calendar to specify your date range; narrow down your search to Stations, ZIP Codes, Cities, Counties, and other options; and enter a location name or identifier in the search box. You can view the results immediately online and also have them delivered to your email address.

The Old Farmer’s Almanac, published since 1792, provides historical weather data for the United States and Canada back through 1945 on its website, based on records provided by the National Climatic Data Center. To find Old Farmer's Almanac weather history by date, enter your ZIP code and the month, date and year of your choice. You can also find weather history by state or province. The results provide high, low and average temperatures, wind speed, precipitation and weather observations. The website also offers an enhanced weather history search that allows you to determine "typical" weather over a range of dates.

Visit Weather Underground to search past weather reports (back through 1945) by city, zip code or airport code. You can choose from daily, weekly or monthly results. As well as maximum temperature, average temperature and minimum temperature, the results provide data on precipitation, wind, wind direction and gust.

If you don't need to search too far back in time for weather information, AccuWeather provides archived daily temperature and precipitation records for about 2,500 weather stations across the United States, as well as many international weather stations. To look up past weather, enter your location in the search box on the home page. This provides current weather conditions for your area. Click on "Month" to find the high, low and average temperatures by month, back through January of the previous year.