Best Time for Outdoor Projects in Idaho

Idaho weather and outdoor projects

Southern Idaho around Boise and Pocatello has a dry climate with hot summer days, cool nights and cold winters. Summer is reliably dry, which makes it a good season for staining and painting, but the big swing between day and night temperatures means the night after you finish can be cold even in late spring and early fall.

The Panhandle in the north is wetter and more like the Pacific Northwest, with more cloud, rain and snow. Late summer can bring wildfire smoke across much of the state. Spring and fall frost dates come early at higher elevations, so the concrete and paint season there is short.

Frost dates in Idaho

In Boise, the median last spring freeze (32°F) is around April 24 and the median first fall freeze is around October 21, a frost-free season of about 179 days.

In Pocatello, the median last spring freeze (32°F) is around May 23 and the median first fall freeze is around September 18, a frost-free season of about 117 days.

Frost dates matter for concrete, which must not freeze in its first 48 hours, for paint and caulk that need nights above their minimum, and for lawn care, since crabgrass preventer goes down as the soil warms in spring. See how late in fall you can stain, paint or seal.

Best time to stain a deck in Idaho

In Boise, the most reliable months are June and September. April–May, August and October can also work on the right days. November–February is too cold, with average highs around 43°F. In March, nights average about 35°F, too cold for the coating to dry and cure overnight. July is hot, with average highs near 93°F and about 22 days a month at 90°F or more, so work early in the day. In April–May and October, nights average about 43°F, so finish early on mild days and check the overnight low. August is hot, with highs near 91°F, so start early and keep out of full afternoon sun.

Pocatello has no month that is easy for this job on average; the best chances come in May–September. November–March is too cold, with average highs around 41°F. In April and October, nights average about 33°F, too cold for the coating to dry and cure overnight. In May–June and September, nights average about 43°F, so finish early on mild days and check the overnight low. July–August is hot, with highs near 89°F, so start early and keep out of full afternoon sun.

Check this week’s hour-by-hour verdict with the deck staining forecast.

Best time to paint outside in Idaho

In Boise, the most reliable months are May–June and September. March–April, August and October can also work on the right days. November–February is too cold, with average highs around 43°F. July is hot, with average highs near 93°F and about 22 days a month at 90°F or more, so work early in the day. March is cool, with highs around 56°F, so choose the warmest afternoons. In April and October, nights average about 41°F, so finish early on mild days and check the overnight low. August is hot, with highs near 91°F, so start early and keep out of full afternoon sun.

In Pocatello, the most reliable months are June. May and July–September can also work on the right days. November–February is too cold, with average highs around 38°F. In March–April and October, nights average about 31°F, too cold for the coating to dry and cure overnight. In May and September, nights average about 41°F, so finish early on mild days and check the overnight low. July–August is hot, with highs near 89°F, so start early and keep out of full afternoon sun.

Check this week’s hour-by-hour verdict with the exterior painting forecast.

Best time to pour concrete in Idaho

In Boise, the most reliable months are May–September. April and October can also work on the right days. November–March averages about 20 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. April and October bring about 4 freezing nights a month, so pick a mild spell and keep curing blankets on hand.

In Pocatello, the most reliable months are June–August. May and September can also work on the right days. October–April averages about 23 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. May and September bring about 4 freezing nights a month, so pick a mild spell and keep curing blankets on hand.

Check this week’s hour-by-hour verdict with the concrete pouring forecast.

Best time to seal a driveway in Idaho

In Boise, the most reliable months are June–September. May can also work on the right days. November–March is too cold, with average highs around 46°F. In April and October, nights average about 41°F, too cold for the coating to dry and cure overnight. In May, nights average about 48°F, so finish early on mild days and check the overnight low.

In Pocatello, the most reliable months are July. June and August–September can also work on the right days. November–April is too cold, with average highs around 44°F. In May and October, nights average about 36°F, too cold for the coating to dry and cure overnight. In June and August–September, nights average about 46°F, so finish early on mild days and check the overnight low.

Check this week’s hour-by-hour verdict with the driveway sealing forecast.

Best time to fertilize or treat a lawn in Idaho

In Boise, the most reliable months are April–June and September–October. March and August can also work on the right days. November–February is too cold, with average highs around 43°F. July is hot, with average highs near 93°F and about 22 days a month at 90°F or more, so work early in the day. March is cool, with highs around 56°F, so choose the warmest afternoons. August is hot, with highs near 91°F, so start early and keep out of full afternoon sun.

In Pocatello, the most reliable months are May–June and September–October. March–April and July–August can also work on the right days. November–February is too cold, with average highs around 38°F. March–April is cool, with highs around 55°F, so choose the warmest afternoons. July–August is hot, with highs near 89°F, so start early and keep out of full afternoon sun.

Check this week’s hour-by-hour verdict with the lawn fertilizer forecast.

How the weather differs across Idaho

Of the places above, Boise has the most good months for staining, painting and concrete combined (10 job-months), and Pocatello has the fewest (4). If you live between them, expect something in between, and higher ground to be cooler with a shorter season.

Monthly weather in Boise

*Days with at least 0.1 inch of rain or melted snow. Freezing nights: average nights a month at or below 32°F. Humidity is calculated from NOAA hourly normal temperature and dew point at 3 PM.

Monthly weather in Pocatello

Use the averages, then check the forecast

These ratings describe a typical month, not a particular week. A warm spell in a “poor” month can give you a good day, and a wet week can spoil a “good” one. Use this page to plan the season, then check the 7-day forecast for your ZIP code before you buy materials or book help. Each project forecast checks the hours after you finish too: overnight lows, dew and rain that would ruin fresh stain, paint, sealer or concrete.

About this data

Monthly temperatures, rain days, snowfall and freeze dates are NOAA National Centers for Environmental Information (NCEI) U.S. Climate Normals for 1991–2020 at BOISE AIR TERMINAL, POCATELLO RGNL AP. Ratings apply the same temperature limits as our forecasts (for example, 50°F or warmer for deck stain and driveway sealer, and no freezing nights for new concrete) to the average month. Your product label always takes priority.