Grow cannabis in Mountain View, CA

Growing cannabis in Mountain View: a season set by cool nights, not hot days

In Mountain View, the afternoon is rarely the problem. The Moffett Federal Airfield station, 2.4 miles away, averages highs of 76 to 78°F from June through September and only about 9 afternoons in a whole year at 90°F. The nights are what stand out: 56 to 59°F through those same months, and under 50°F on average until April 25.

Cool nights are a resource when you plan for them and a brake when you do not. Is your grow using them, or fighting them?

California home grow rules (as of October 2026)

Adults 21 and over: yes. Plant limit: 6 living plants per private residence, however many adults live there.

Locked space, not visible from a public place; cities and counties can set reasonable rules for indoor grows (but cannot ban them) and may ban outdoor grows; a landlord may prohibit growing on a rental. Source: Department of Cannabis Control; conditions: Prop 64 text as passed in 2016 (H&S Code 11362.2 and 11362.45). Local rules (landlords, HOAs, city codes) can add more; this is a summary, not legal advice.

Putting Mountain View's cool nights to work indoors

In summer, night air is cheap cooling. A tent in a Mountain View apartment can draw intake after dark that runs about 18 to 20 degrees under the afternoon high, so lights that run overnight pair their heat with the coolest air of the day. With so few 90°F afternoons, a daytime schedule also works through much of the summer, as long as the exhaust keeps up.

Winter turns the nights against you. December and January lows average about 42°F, and the station counts about 2 freezing nights a year. A garage tent with the lamp off can drift toward that, and cold roots slow everything down. Run the lights through the night from November into February so their heat covers the coldest hours, and give the young plants a heat mat underneath.

Humidity moves with the calendar. January's outdoor reading averaged 83 percent in 2024, but a heated room dries that out; only an unheated garage or damp room needs a dehumidifier then. Summer started dry, at 58 percent in June, and reached 70 in September, the dampest of the summer and fall months measured, before October fell to 57. A September flower room needs the dehumidifier more than a July one does.

Month	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high °F	59	62	65	68	72	76	77	77	78	74	66	59
Avg low °F	42	45	47	49	53	56	59	59	57	53	46	42
Humidity %	83					58	62	66	70	57

Highs and lows: NOAA 1991 to 2020 normals, Moffett Federal Airfield station (2.4 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.

Outdoors in Santa Clara County

The state permits 6 living plants per private residence, however many adults share it, in a locked space no one can see from a public place. Each city and county can regulate or prohibit outdoor grows, so check Mountain View's rules first.

Where outdoor plants are allowed, start seeds inside in early March (March 4 to 18) and transplant from April 15. Nights still average below 50°F until April 25, so expect a slow first couple of weeks. September is the warmest month, with a 78°F average high, and nights hold at 50°F or more until October 30, so photoperiods can finish in October, when the air averaged 57 percent. The cost is a little chill, with October nights near 53°F. Finishing early, in September, would mean ripening in the damper 70 percent air.

Frost	Rare: about 2.4 freezing nights a year
Nights stay 50°F or warmer	Apr 25 to Oct 30
Start seeds or clones indoors	Mar 4 to Mar 18
Move plants outdoors	Apr 15 or later

Your Mountain View numbers, kept close

A Mountain View grow runs on measurements. Those numbers take seasons to collect. Other growers you meet at the Sunday farmers market on West Evelyn Avenue or the Art and Wine Festival may ask about them, and sharing is your choice.

Canna GLAP encrypts your grow records on your phone before upload. If someone broke into our servers, they would get encrypted grow records they cannot decode, and no key. It keeps the journal private; it cannot hide a tent's glow or a plant's smell from a roommate.

What is encrypted: your plants, notes, photos, feed logs and harvests. What is not: account details (such as your email, name and plan), a grow name or town if you type one, your team, and your sensors' names. The full list: what a hacker would get.

Questions growers in Mountain View ask

Is it too cold at night to grow cannabis outdoors in Mountain View?

Not in summer, when nights average 56 to 59°F. In spring they stay under 50°F on average until April 25, so plants set out April 15 start slowly.

Should I run my grow lights at night in Mountain View?

In winter, yes: December and January lows average about 42°F, and the lamp's heat helps most then. In summer either schedule can work, since only about 9 days a year reach 90°F.

When is the dampest time for a Mountain View grow?

Among the summer and fall months measured in 2024, September, at 70 percent. January was damper outdoors, at 83 percent, but heated rooms dry that out.

Growing near Mountain View

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