Vitamin D in Toronto

Toronto has a pronounced seasonal change in solar angle, so the same outdoor routine produces very different modeled results in January and July. Location affects possible vitamin D production from sunlight; it does not change the age-based dietary reference intake or determine whether a particular person needs a supplement.

See Toronto's sunlight estimate in the calculator

What the monthly model shows

The chart uses latitude 43.6532°, longitude -79.3832°, and elevation 76 m. It is model version 2026.09 with reference year 2026. It is not a weather forecast or measured local UV record.

Modeled daily IU from 30 minutes between 10:00 and 14:00 local solar time, skin type II, long sleeves and pants (15% exposed), 40% cloud cover, grass surface, and SPF 0. Customize every input.
Monthly modeled vitamin D production and gap to adult RDA in Toronto
MonthModeled sunlightGap to RDA*
January20 IU/day380 IU/day
February114 IU/day286 IU/day
March426 IU/day0 IU/day
April1,127 IU/day0 IU/day
May1,947 IU/day0 IU/day
June2,753 IU/day0 IU/day
July2,983 IU/day0 IU/day
August2,407 IU/day0 IU/day
September1,350 IU/day0 IU/day
October402 IU/day0 IU/day
November60 IU/day340 IU/day
December12 IU/day388 IU/day

*Mathematical gap after modeled sunlight and an assumed 200 IU/day from food. This is not a supplement recommendation.

How much vitamin D do adults need?

Health Canada recommends 600 IU (15 µg) daily from all sources for ages 1–70 and 800 IU (20 µg) after age 70. Its food guide advises adults 51 and older to take a daily 400 IU supplement.

Read the current Health Canada guidance

Vitamin D and seasonal depression

Seasonal affective disorder is a form of depression related to seasonal changes in daylight. Low vitamin D can coexist with it, but research on vitamin D as a SAD treatment is mixed. Established options include clinician-guided light therapy, psychotherapy, and medication. Read the evidence guide to vitamin D and SAD.

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