CannaGLAP
Grow cannabis in Corona, CA
Growing cannabis in Corona: hot afternoons, cool nights, and a few frosty nights each winter
Corona's weather comes from the Chino airport station, 8 miles away at 650 feet, and its most useful number is the gap between afternoon and night. In every month of the year, the average high and the average low sit 27 to 33 degrees apart. August is the widest: about 96°F by day, 63°F by night.
Then there is winter. The station still counts about 11 freezing nights a year, most of them from December through February. So which is your grow really set up for: the afternoon, the night, or the cold snap?
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.
Corona indoors: use the cool night, respect the afternoon
Summer afternoons are fierce. The station counts about 23 days of 90°F heat in July, 25 in August and 19 in September, about 99 across the year. A garage tent near Grand Boulevard or in Village or Jameson can climb past 90°F inside once a wall takes the afternoon sun. The night is your ally: with lows of about 60 to 63°F from July through September, the lamp's on hours belong in the dark.
The air is moderate, not desert dry. Humidity averaged about 63 percent in June, 57 in July, 55 in August, 58 in September and 51 in October, the driest month measured. That keeps bud rot pressure modest in fall, and young plants rarely need a humidifier outside the driest weeks. A fan under the canopy and an exhaust fan venting outside cover most flower runs.
Winter is short but real. December averages a low near 40°F with about 5 freezing nights, and January about 3. A tent in an unheated garage needs a heat mat under young plants, pots lifted off the slab, and a lamp scheduled through the small hours. January's 72 percent outdoor reading only matters if that garage is damp as well as cold.
| 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 % | 72 | 63 | 57 | 55 | 58 | 51 |
Highs and lows: NOAA 1991 to 2020 normals, Chino Airport station (8 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
Outdoors in Corona: a long season with a hot middle
California sets the limit at 6 living plants per private residence, however many adults live there, kept in a locked space where the public cannot see it. Cities and counties can also regulate home growing and may ban outdoor plants, so check Corona's current rules before you plant outside.
If an outdoor spot is allowed and qualifies, seeds go in March 4 to 18 and plants go out April 15. A typical last frost comes around January 17, and the early first frost around November 27, about 226 days after planting. The middle of that run is hot: use big containers or in-ground beds, mulch, water at dawn and rig shade for July through September. Photoperiod plants flower into October, when highs ease to about 85°F and nights to about 53°F, a kinder finish.
| 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 growing city, a quiet grow
Corona is a city of about 170,000, and its calendar keeps pulling people into the same places: the Summer Street Fair, the Independence Day Festival at Santana Park, a weekend at Corona Heritage Park. A grower you meet there might be glad to trade cuttings. The record of your last run does not need to come along.
Canna GLAP encrypts each run's records on your phone before uploading them. If our servers were ever broken into, the intruder would carry off grow data they could not read, without a key to read it.
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 Corona ask
Does it freeze in Corona?
Sometimes. The nearby Chino airport station averages about 11 freezing nights a year, most of them from December through February, and frost can come as early as November 27 in an early year.
When should I plant cannabis outside in Corona?
Sow seeds indoors March 4 to 18 and set plants out on April 15, if your local rules allow an outdoor grow. Plan for about 226 days before an early first frost.
Should I run my grow lights at night in Corona?
From July through September, yes. Afternoons average 93 to 96°F while nights fall to about 60 to 63°F, so running the lamp after dark keeps its heat out of the hottest hours.
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