The U.S. has just come through the warmest spring on record—indeed, the warmest 12-month stretch since record-keeping began.

With headlines like “Warmest spring heats up economy,” readers weary of bad economic news might be forgiven for thinking that a little global warming is not such a bad thing. But the warming we’ve experienced globally over the past 30 years is more than “a little.” And in the U.S., it’s likely contributing to drought and wildfires in the West and more extreme weather nationwide.

This past May came in as the second warmest on record globally, trailing only May of 2010. For land area only, it was the warmest on record, at 2.18 degrees F above average. It was also the 36th consecutive May, going back to 1976, with global temperatures above the 20th-century average.

So far in the U.S., 2012 has featured a historic run of hot weather, starting with a “Summer in March” that smashed temperature records across the country. Since then, temperatures across much of the U.S. have hardly cooled. For the first time since records began in 1885, March, April, and May all ranked among the top 10 warmest.

Overall, this past spring averaged 5.2 degrees F above average, breaking the previous record by an unprecedented 2 degrees. The U.S. Climate Extremes Index, which tracks the percent of the country experiencing extremes in temperature, precipitation, drought, and tropical cyclones, hit a record high of 44 percent, double the normal value for this time of year.

The impact of this unusually hot weather goes well beyond employers picking up summer help a month early and car buyers shifting purchases from June to May. As early as April 25, some news outlets were warning of the enhanced risk of drought and wildfire from the near record low snowpacks throughout the western United States. Unfortunately, these warnings proved prescient, as wildfires in New Mexico broke state records (set just last year) and the most destructive wildfire in Colorado history has burned 189 homes amid reduced snowpack levels and forests weakened by pine bark beetle outbreaks related to recent warm winters.

In addition, drought has expanded across the west, reducing water supplies for an already stressed region. Last year, Texas alone lost more than $7 billion from drought and the state has yet to recover from the water shortages and or the economic fallout. Elsewhere, forests ravaged by fire and pine bark beetle will take decades to recover, as will the jobs and businesses they help sustain.

When adding up the costs and benefits of extreme weather, it is important to consider whether a few weeks of nice weather and any short-term economic boost they might generate are worth the longer term costs incurred, including the risk of billions in drought losses and thousands of homes destroyed by wildfire. Climate change presents both opportunities and risks, but over the long haul, the risks of unabated climate change will almost certainly eclipse the opportunities.