CannaGLAP
Grow cannabis in Chino Hills, CA
Growing cannabis in Chino Hills: buds that start forming in the hottest month
Chino Hills saves its hardest heat for the stage a cannabis plant can least afford it. August is the hottest month here, with an average high of 96°F and about 25 afternoons at 90°F or hotter. It is also when outdoor plants usually begin to flower.
Heat in veg costs some growth. Heat in early flower can cost smell and density a plant rarely makes back. So which month is your cooling really sized for: July, or August?
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.
Cooling a Chino Hills flower room through August
The figures come from the Chino airport station, 5.6 miles away at 650 feet. It averages about 23 hot afternoons in July, 25 in August and 19 in September, so a tent in a garage or an upstairs bedroom spends close to three months near its limit. Run the lamps at night. August nights average about 63°F, some 33 degrees under the afternoon high, and that cooler intake air is the cheapest cooling a grow room gets.
Then plan the calendar around August. A plant switched to 12 hours of light in late spring is deep into flower, or done, before the worst of it; one switched in late July starts blooming in the hottest stretch. If an August flower is unavoidable, add exhaust, raise the lamp, and read the temperature at the canopy, not the thermostat.
Moisture matters less. In 2024, outdoor humidity eased from 67 percent in June to 60 in August and 59 in October, moderate bud rot pressure for a garage that breathes outside air. An air conditioner pulls water out as it cools, which often takes a closed room lower still.
Winter is short, and it does freeze a little. December, the coldest month, averages lows near 40°F and about 5 of the year's roughly 11 freezing nights. A heat mat under seedlings and lights through the coldest hours keep a garage tent's roots warm.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 70 | 70 | 73 | 77 | 81 | 88 | 94 | 96 | 93 | 85 | 76 | 69 |
| Avg low °F | 42 | 43 | 46 | 49 | 54 | 59 | 63 | 63 | 60 | 53 | 45 | 40 |
| Humidity % | 75 | 67 | 63 | 60 | 62 | 59 |
Highs and lows: NOAA 1991 to 2020 normals, Chino Airport station (5.6 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
Outdoors in Chino Hills and San Bernardino County
State law sets the cap at 6 living plants for each private residence, no matter how many adults share it, and wants them locked away and hidden from public view. Local governments may add reasonable rules for indoor plants, though an indoor ban is off the table for them, and they can forbid outdoor plants entirely. Look up the Chino Hills rules first.
Where outdoor plants are permitted, seeds go under lights March 4 through 18 and young plants go outside on April 15 or later. Even an early first frost waits until about November 27, about 226 outdoor days. The squeeze comes in the middle, when buds form under August and September highs of 96°F and then 93°F. Midday shade, deep morning watering and pots big enough to hold a day's water all earn their place.
| Last spring frost | Jan 17 in a typical year, Feb 22 to be safe (later only 1 year in 10) |
|---|---|
| First fall frost | Dec 19 typical, as early as Nov 27 (1 year in 10) |
| Frost-free season | about 335 days |
| Nights stay 50°F or warmer | Apr 22 to Oct 28 |
| Start seeds or clones indoors | Mar 4 to Mar 18 |
| Move plants outdoors | Apr 15 or later |
A Chino Hills grow, kept to yourself
Chino Hills is a city that gathers: Concerts in the Park, Movies in the Park, the Wine Walk, the McCoy Family Campout. Talk turns to gardens. What you have worked out about getting buds through August does not have to come up.
The app scrambles each grow entry on your phone before it travels to our servers. Someone who broke in there would leave with grow records they could not open and no key to open them. Your notes on what carried a crop through a 96-degree August stay with you. That covers the journal only; it does not hide a fan's hum or a smell drifting over the fence.
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 Chino Hills ask
What is the hottest month for growing cannabis in Chino Hills?
August, with an average high near 96°F and about 25 days at 90°F or hotter at the Chino airport station. Indoors, run the lights at night and keep early flower out of August when you can.
Does Chino Hills get frost?
A little. The Chino airport station averages about 11 freezing nights a year, most in December and January, and a spring frost after February 22 is rare.
Do I need a dehumidifier to grow cannabis in Chino Hills?
Often only a small one. Outdoor humidity averaged 59 to 63 percent from July through October in 2024, and an air conditioner removes water as it cools.
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