CannaGLAP
Grow cannabis in San Pablo, CA
Growing cannabis in San Pablo: a winter that brings damp more than cold
San Pablo's winter barely gets cold. At the Richmond station, 3.4 miles away, the average night slips below 45°F only between about December 11 and January 31, and a freezing night is rare enough to skip most years.
What winter brings instead is water. Outdoor air averaged 84 percent humidity in January 2024, the dampest of the months measured. For a tent in a heated bedroom that hardly matters. For a tent in an unheated garage, it is the season's main problem. Which one is yours?
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.
A San Pablo garage tent through the wet months
Start with where the tent breathes. A garage with no heat runs close to outdoor conditions: winter nights in the mid 40s and, in January 2024 at least, very damp air. Moisture in air that cold and wet can condense on cool surfaces, tent walls and leaves included, and gray mold and powdery mildew both get their start in that film.
Warmth is the cheapest fix, because warming air lowers its relative humidity. Run the lamp through the coldest hours of the night, and let the exhaust run in short bursts rather than nonstop, so it swaps out stale air without flooding the tent with chill. A small dehumidifier handles what the lamp does not. A heated bedroom needs none of this in winter, since the heating dries the air.
Seedlings feel the cool first. Seeds started March 4 to 18 meet March nights near 47°F, so a seedling mat under young plants keeps their roots growing until spring settles in.
The rest of the year is mild. About 5 afternoons a year reach 90°F, most of them in September and October. The damp comes back for fall flowering, though: September 2024 averaged 77 percent, so a flower room needs its dehumidifier running again by then.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 58 | 61 | 64 | 67 | 69 | 72 | 71 | 72 | 75 | 73 | 65 | 58 |
| Avg low °F | 44 | 46 | 47 | 49 | 52 | 54 | 55 | 56 | 56 | 54 | 49 | 44 |
| Humidity % | 84 | 66 | 72 | 74 | 77 | 63 |
Highs and lows: NOAA 1991 to 2020 normals, Richmond station (3.4 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
San Pablo outdoors, from April to the fall damp
State law lets a private residence keep 6 living plants, the same number however many adults live there, in a locked space that people in a public place cannot see. Cities and counties can set reasonable rules for indoor grows but cannot prohibit them, and they can prohibit outdoor grows, so check the local rules that cover your address before you plant.
Where outdoor plants are allowed, plant out from April 15, though nights average below 50°F until April 23, so the first weeks are slow. Frost is not what ends the season here. Moisture is: buds ripening in September sat in air that averaged 77 percent in 2024, and October fell to 63. A variety that finishes in October ripens in the drier of those two months, at the cost of nights near 54°F; one that finishes in September ripens in the damp.
| Frost | Rare: less than 1 freezing night a year on average |
|---|---|
| Nights stay 50°F or warmer | Apr 23 to Nov 7 |
| Start seeds or clones indoors | Mar 4 to Mar 18 |
| Move plants outdoors | Apr 15 or later |
A garage grow on a close-packed block
San Pablo is dense, set between Richmond and the I-80 corridor. A garage tent's hum can carry through a shared wall, and no app can quiet that. What an app can do is keep the journal yours: what you learned about drying out a January garage belongs to you, not to the next grower who asks.
Canna GLAP encrypts each entry on the phone before anything goes up, so our servers only ever store it locked. Someone who broke into them would find grow records they could not open and no key to open them with.
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 San Pablo ask
Can I grow cannabis in a San Pablo garage in winter?
Yes, with warmth and a dehumidifier. December and January nights average about 44°F, so run the lamp through the coldest hours and dry the damp air the garage takes in.
Does San Pablo get frost?
Very rarely. The Richmond station averages less than one freezing night a year, and the average night stays at 50°F or warmer from April 23 to November 7.
Do I need a dehumidifier in San Pablo?
In an unheated garage, yes, through winter. For flowering, usually: outdoor air ran damper each month from June through September in 2024. A heated room in winter needs one least, since the heating dries the air.
Growing near San Pablo
- Grow cannabis in Richmond, CA 2 miles
- Grow cannabis in El Cerrito, CA 4 miles
- Grow cannabis in Hercules, CA 5 miles
- Grow cannabis in Berkeley, CA 7 miles
- Grow cannabis in San Rafael, CA 10 miles
All California cities · Every state where adults may grow at home