Is San Diego sunnier than Ontario?

Ontario is the sunnier: about 3,804 hours of sunshine a year versus 2,854 — a difference of 950 hours.

Which is warmer, San Diego or Ontario?

Ontario is warmer across the year: average daytime highs of 27°C (81°F) versus 18°C.

Which is better in winter (November–February), San Diego or Ontario?

Ontario scores better across November–February: 85/100 average versus 68, with daytime highs around 20°C.

San Diego vs Ontario: which is sunnier?

🇺🇸 United States vs 🇺🇸 United States · 152 km apart · long-term climate normals (NASA POWER, 2001–2020)

Ontario is the sunnier overall: about 3,804 hours of sunshine a year to San Diego's 2,854. Ontario has the higher Sunshine Score in 9 of 12 months, San Diego in 3.

Scores are the 0–100 Sunshine Score — sunshine, daytime warmth and dryness in one number, per month.

At a glance

	San Diego	Ontario
Sunshine hours / year	2,854	3,804
Sunniest month	July (95/100)	May (99/100)
Nov–Feb average score	68/100	85/100
Jun–Aug average score	89/100	70/100
Rain / year	269 mm	290 mm
Peak midday UV	9 (very high)	10 (very high)

San Diego vs Ontario month by month

Month	Sunshine Score		Day high °C		Rain mm
Month	San Diego	Ontario	San Diego	Ontario	San Diego	Ontario
January	66	82	17°	19°	42	58
February	58	88	16°	20°	52	63
March	60	94	16°	22°	29	32
April	70	97	17°	25°	17	18
May	71	99	17°	28°	7	7
June	76	90	18°	33°	26	1
July	95	59	20°	36°	4	5
August	95	60	21°	36°	2	3
September	95	79	22°	34°	5	5
October	93	97	21°	29°	14	16
November	84	96	19°	23°	23	24
December	65	74	17°	18°	48	58

The sunnier month by month: Jan Ontario · Feb Ontario · Mar Ontario · Apr Ontario · May Ontario · Jun Ontario · Jul San Diego · Aug San Diego · Sep San Diego · Oct Ontario · Nov Ontario · Dec Ontario.

When to pick which

November–February: Ontario (average score 85/100 vs 68). Ontario is the warmer, around 20°C daytime highs vs 17°C. See the winter sun ranking.
March–May: Ontario (average score 97/100 vs 67). Ontario is the warmer, around 25°C daytime highs vs 17°C.
June–August: San Diego (average score 89/100 vs 70). Ontario is the warmer, around 35°C daytime highs vs 20°C.
September–October: San Diego (average score 94/100 vs 88). Ontario is the warmer, around 32°C daytime highs vs 22°C.

Full month-by-month guides: San Diego weather by month · Ontario weather by month · Best time to visit United States.

More comparisons: San Diego vs Los Angeles · San Diego vs Tijuana · San Diego vs Mexicali · Ontario vs Los Angeles · Ontario vs Santa Barbara · Ontario vs Palm Springs · all head-to-heads