Since 1998 average temperatures have exceeded the historical average, still when the cold strikes it comes with steeper temperature drops. All construction estimates rely somewhat on historical information. When it comes to the weather, though, the past is not exactly reliable.
In 2020, there were a total of 22 extreme weather and climate events costing $1 billion or more and totaling $95 billion in the U.S., according to the National Oceanic Atmospheric Administration (NOAA). Last year’s billion-dollar disaster events amounted to the fourth-highest annual cost since 1980.
Heatwaves, unusually heavy rainfalls, wildfires, and severe storms are getting more frequent and more costly. Even normal weather events are getting more expensive. Somewhere in all of your estimates, you will need to deal with weather costs, so plan to include them when estimating.
Don’t Depend on Long-Range Forecasts
You might rely on NOAA and the Old Farmer’s Almanac. But, NOAA is predicting a warmer than average winter for the country with no area having below average temps. On the other hand, the Old Farmer’s Almanac is predicting the opposite with only the Western third of the country getting near normal temperatures. It’s pretty much the same story for the precipitation forecast.
So, what about the short-term forecasts? The 10-day forecasts are accurate about 50 percent of the time. For 80 percent accuracy or higher, use the five-day and seven-day forecasts. None of that is of much use when estimating three or four months out, though.
How about using weather history? Trouble is, the weather patterns are changing right along with the climate, and it’s happening faster than before.
The reality is that predicting weather any more than 10 days in the future is a crapshoot. Use worst-case scenarios for activities directly affected by the weather. That way, if the worst case happens, you’re covered. If not, the money and time you allocated to cover worst-case weather is passed back to the owner or is available for other surprises.
How you allocate the money is important. Whether to include it in contingency funds or account for it as a line item is something to hash out with the owner. But, a side benefit of making your weather expenses transparent is the owner will see you are dealing with this variable upfront, instead of solely on the backside with claims.
Validate Your Assumptions
Did you assume ice wouldn’t be a big problem? Did you assume standard crew productivity? If so, you might want to revisit those assumptions. Particularly in freezing weather, things just don’t work as they do when it’s 70 degrees. Your machines might not start. Worse still, frozen soil could require extreme measures and specialized equipment. It’s going to take longer to get the site ready each day. Your people will perform at a lower efficiency. If it’s 20 degrees outside, the typical worker will be 20 percent less efficient. If it’s zero degrees, their efficiency falls down by 40 percent.
By questioning your assumptions as you estimate, you’ll uncover holes in your logic. It’s better to find them before submitting the bid.
Review Past Jobs
The results from past jobs contain insights into how weather affects your crews. When you review these, you can learn about production results during weather events. Even if you didn’t use job costing on those earlier jobs, you might still find productivity data by comparing money spent on activities during bad weather. Not only will you see how the costs increased, but you’ll also see how the schedule was affected. If there were claims you filed for bad weather, those dollar amounts also tell the story of how much weather costs your projects.
If you are a Procore user, you have a weather section in the Daily Log tool. It automatically pulls the local weather from the weather software used on your project and offers a way for you to record weather conditions.
Besides providing data for claims, the weather section allows you to send alerts to project participants when weather causes delays. It also becomes a handy record you can refer to when preparing future estimates. You can use it to compare team productivity against weather conditions. You can also check the conditions that led to claims. By comparing the claims to the budget, you see how much weather events cost the project and you can apply that knowledge to future estimates.