Boise Weather & Climate

Gardening In Boise

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The weather in Boise can be described as such. Not too hot, not to cold! With low humidity and very little precipitation Boise is almost idyllic. Wind is associated mostly with storms, a year in the weather might go like this. The Rocky Mountains push the vast majority of the cold to Denver. Most years we never get below zero. The last dusting of snow might come at the end of March. But you also may have to mow the first week or so of April. May is cool and cloudy with intermittent storms. May 9-15 is the last night we will get frost. June is a transition, cool in the beginning and warmer at the end. Typically sometime in the second week of June the clouds go away and we have clear sky's all the way through September. July and August are characterized by cool nights and hot days. That said we can have the occasional monsoonal thunderstorm anytime from May to September, they are typically viewed as a respite from the heat. September highs start to slide until 80 degree days are the rule. October is for color. As the night time lows start to toy with freezing the City of Trees lights up. At dusk on Halloween you can be in shirt sleeves or a winter parka depending on the year. We might or might not get a skiff or even two inches of snow in November. The leaves are on the ground and the skiers are doing the snow dance for the mountains hoping for a Thanksgiving opening day at Bogus Basin, Tamarack or Brundage. Can you say white Christmas in Boise? Only about 50% of the time. Some years it may snow in the valley and melt of before Santa arrives, other years it comes as rain in the valley. Some years it just does not snow much in either locale. In 2016-17 it snowed in both and stayed on the ground through January.

How Many Sunny Days Does Boise Idaho Get Each Year?

Nearly same number as Las Vegas, 206 for Boise Idaho. Boise is high desert and only gets 11 inches of precipitation a year. If not for the dams upstream on the Boise river we would look more like Winnemucca.


When Does It Start To Get Cold In Boise Idaho?

The first frost is sometime in October usually not before the 15th. September has a few days in the high 80's every year. October can be refreshing or down right hot. Last year we harvested our last tomatoes on the 13th of October. Leaves are gone by first week to second week of November. It can hit teens at night and winter time conditions in November. It can also be 79 in November.


How Cold Does Boise Get?

During December and January the overnight temps are around or average 23°F with the lowest temperature of -25.1°F being recorded in December 1990. I was teaching snowboarding in Sun Valley that year. I had a 10 year old who was so gung-ho, not even the offer of free hot chocolate would get him off the hill. Typically lows in upper teens at night and highs near or just above freezing. A few times a winter we will have warm spells when we hit 50's for highs.


How Hot Does It Get In The Summer In Boise Idaho? 

The warmest month in Boise, Idaho is July with an average high temperature of 92.9°F. The hottest day on record was July 28 1934 when the temperature hit 111.2°F. Rarely does it get above 106 degrees. We average about 8 days a year over 100 degrees. Record number of 100 degree days in one year was 18. Typically cool desert mornings high 60's with highs in the late afternoon in the mid 90's.

How Long Is The Growing Season & What Zone Is Boise In?

Flowers In Boise167 Days… On Average. Zone 6 is your best bet for deciding what to plant! Plant peas, lettuce and other cold hardy plants in late March or April. Wait until May 15 or use a wall of water for tomatos and such. We freeze October 15. Tomato's, watermelon, corn, pumpkin, cucumbers, herbs all grow like crazy. Our soil is high acid... most do not add lime but add organics. Gardening is great for flowers or edibles there are lots of suppliers for starts and shrubs. A few of our favorites are D&B Supply which is a farm, ranch and gardening store with locations around the valley. The best selection and quality in my opinion for perennials, annuals and veggies is Edwards Greenhouse and Nursery. The hot tip is the wagon load sale they have each summer. I think it is in late June or early July. It is a flat fee for everything you can fit in your wagon. If you want low maintenance native drought tolerant plants try Draggin Wings.


Can I Grow Tomato’s In Boise Idaho?

Oh Yeah! With wall of waters you can plant them in late April and have tomato’s sometime in July depending on overnight temperatures. They will not ripen until the overnight low's stay above a certain temperature at night. I think just below 60 degree's. So around July 4 they really come on strong.

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