Kelowna
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kelowna clear sky chart from 2005-11-06 to 2025-09-04.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	6% 7% 3 8% 5% 5% 5% 4 6% 8% 41%	130330
	Night	7% 10% 4 9% 6% 5% 6% 4 6% 7% 36%	126982
Transparency	Day	40% 8% 17% 22% 10% 3	130049
	Night	44% 9% 18% 19% 8% 1	126840
Seeing	Day	12% 10% 26% 29% 17% 6%	16470
	Night	13% 6% 23% 34% 20% 3	24802

By Month

Percentage Cloud Cover NW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	9% 14% 7% 15% 9% 7% 6% 4 6% 6% 18%	3475
	11th to 20th	Day	5% 12% 3 7% 6% 6% 6% 5% 7% 11% 31%	3616
	21st to end	Day	6% 12% 5% 12% 9% 7% 5% 4 6% 6% 28%	4004
February	1st to 10th	Day	8% 14% 4 11% 8% 7% 6% 5% 6% 6% 25%	1636
	11th to 20th	Day	4 13% 5% 10% 7% 8% 7% 4 6% 7% 28%	1755
	21st to end	Day	6% 13% 4 11% 8% 7% 7% 6% 7% 7% 23%	1633
March	1st to 10th	Day	3 8% 4 10% 7% 6% 7% 5% 8% 9% 32%	4518
	11th to 20th	Day	3 6% 3 9% 6% 5% 6% 5% 7% 8% 42%	4753
	21st to end	Day	7% 12% 4 10% 7% 6% 6% 5% 7% 8% 28%	5919
April	1st to 10th	Day	7% 11% 4 9% 7% 6% 5% 6% 8% 9% 27%	2400
	11th to 20th	Day	7% 10% 3 9% 7% 5% 6% 4 7% 9% 33%	2397
	21st to end	Day	6% 10% 3 10% 5% 6% 6% 4 7% 8% 33%	2735
May	1st to 10th	Day	5% 6% 3 8% 5% 5% 4 4 6% 8% 46%	6320
	11th to 20th	Day	8% 8% 4 8% 6% 5% 6% 5% 8% 10% 31%	6277
	21st to end	Day	9% 7% 3 8% 5% 5% 5% 4 6% 8% 38%	6967
June	1st to 10th	Day	12% 8% 3 8% 6% 6% 5% 4 6% 7% 35%	3016
	11th to 20th	Day	13% 8% 3 8% 6% 6% 6% 5% 7% 8% 32%	3200
	21st to end	Day	7% 5% 2 6% 4 5% 6% 4 7% 9% 44%	3200
July	1st to 10th	Day	3 3 1 3 3 3 4 3 5% 7% 65%	6903
	11th to 20th	Day	3 2 1 3 3 3 3 2 4 6% 71%	6371
	21st to end	Day	3 2 1 3 2 3 3 4 6% 9% 64%	6874
August	1st to 10th	Day	2 2 1 3 2 3 4 4 7% 9% 64%	4541
	11th to 20th	Day	2 2 1 4 3 4 5% 4 7% 9% 57%	4453
	21st to end	Day	6% 4 1 5% 4 4 5% 3 7% 8% 53%	4354
September	1st to 10th	Day	4 4 2 6% 4 3 4 4 5% 8% 56%	2317
	11th to 20th	Day	6% 4 2 7% 4 5% 6% 4 6% 7% 48%	2256
	21st to end	Day	9% 7% 2 6% 4 4 5% 4 6% 8% 44%	2076
October	1st to 10th	Day	7% 6% 3 8% 5% 5% 5% 4 5% 6% 45%	3180
	11th to 20th	Day	15% 7% 3 6% 4 5% 5% 4 6% 7% 37%	3049
	21st to end	Day	8% 9% 3 10% 6% 7% 6% 4 5% 8% 35%	3101
November	1st to 10th	Day	11% 13% 4 11% 6% 6% 7% 4 7% 7% 24%	1674
	11th to 20th	Day	7% 12% 4 12% 10% 7% 7% 5% 7% 7% 22%	1600
	21st to end	Day	9% 12% 4 11% 10% 6% 7% 6% 7% 8% 19%	1469
December	1st to 10th	Day	7% 8% 3 11% 8% 7% 8% 7% 7% 6% 28%	2290
	11th to 20th	Day	9% 13% 6% 16% 9% 7% 6% 5% 6% 6% 16%	2642
	21st to end	Day	6% 14% 6% 14% 10% 8% 7% 5% 6% 7% 17%	3359
January	1st to 10th	Night	11% 21% 8% 14% 6% 7% 7% 4 5% 5% 13%	6431
	11th to 20th	Night	5% 10% 4 11% 6% 6% 8% 7% 5% 8% 29%	6282
	21st to end	Night	7% 13% 5% 12% 7% 6% 5% 4 7% 6% 28%	6952
February	1st to 10th	Night	10% 15% 5% 13% 7% 5% 6% 4 7% 7% 21%	2760
	11th to 20th	Night	7% 14% 5% 10% 7% 5% 5% 3 6% 7% 32%	2532
	21st to end	Night	7% 13% 6% 12% 6% 6% 6% 4 6% 8% 26%	1996
March	1st to 10th	Night	4 8% 3 7% 5% 6% 6% 5% 8% 11% 35%	5376
	11th to 20th	Night	3 8% 3 9% 6% 6% 6% 5% 6% 8% 41%	5231
	21st to end	Night	8% 11% 4 10% 7% 7% 7% 5% 8% 8% 26%	5055
April	1st to 10th	Night	6% 9% 3 8% 7% 6% 6% 4 8% 8% 35%	2000
	11th to 20th	Night	6% 9% 3 8% 7% 6% 6% 5% 7% 7% 36%	1954
	21st to end	Night	7% 9% 3 8% 6% 6% 6% 5% 7% 7% 37%	1662
May	1st to 10th	Night	4 6% 3 7% 6% 5% 4 4 7% 8% 47%	3640
	11th to 20th	Night	6% 7% 3 9% 5% 5% 5% 4 6% 9% 38%	3616
	21st to end	Night	6% 6% 2 5% 4 4 5% 5% 7% 8% 47%	3890
June	1st to 10th	Night	8% 8% 2 8% 5% 6% 5% 5% 6% 8% 39%	1379
	11th to 20th	Night	10% 6% 3 7% 7% 5% 4 6% 7% 9% 37%	1200
	21st to end	Night	4 5% 2 7% 4 5% 5% 5% 6% 8% 50%	1200
July	1st to 10th	Night	4 2 1 3 2 4 4 3 6% 7% 65%	3039
	11th to 20th	Night	3 2 1 3 2 2 3 2 5% 6% 71%	3584
	21st to end	Night	4 3 1 3 3 3 3 3 5% 7% 66%	3969
August	1st to 10th	Night	2 1 1 3 3 4 5% 4 7% 8% 63%	2609
	11th to 20th	Night	3 2 1 3 3 4 5% 4 6% 10% 60%	2591
	21st to end	Night	6% 4 2 5% 3 4 4 4 6% 7% 55%	3565
September	1st to 10th	Night	4 3 1 5% 4 4 4 3 6% 7% 59%	1930
	11th to 20th	Night	7% 5% 2 5% 3 4 4 3 5% 7% 53%	1923
	21st to end	Night	8% 6% 2 7% 4 4 4 4 5% 8% 47%	2101
October	1st to 10th	Night	6% 5% 2 6% 4 5% 6% 4 6% 7% 48%	3800
	11th to 20th	Night	15% 7% 3 6% 4 5% 4 3 5% 8% 40%	3884
	21st to end	Night	10% 9% 4 9% 6% 6% 5% 4 5% 7% 37%	4457
November	1st to 10th	Night	12% 13% 4 9% 5% 6% 5% 4 6% 6% 28%	2625
	11th to 20th	Night	10% 12% 5% 11% 9% 6% 7% 5% 6% 6% 23%	2800
	21st to end	Night	9% 15% 5% 13% 7% 6% 7% 5% 7% 7% 19%	2910
December	1st to 10th	Night	6% 11% 3 10% 6% 6% 8% 6% 7% 7% 29%	4890
	11th to 20th	Night	10% 18% 7% 16% 8% 6% 5% 5% 5% 5% 15%	5550
	21st to end	Night	9% 15% 6% 15% 9% 7% 7% 5% 5% 5% 17%	7599

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	62% 13% 15% 9% 1	3475
	11th to 20th	Day	43% 10% 28% 14% 2 3	3640
	21st to end	Day	55% 11% 20% 13% 1	4004
February	1st to 10th	Day	59% 11% 12% 11% 6% 1	1636
	11th to 20th	Day	54% 12% 17% 13% 4	1764
	21st to end	Day	57% 12% 15% 11% 4	1633
March	1st to 10th	Day	45% 9% 19% 18% 9%	4518
	11th to 20th	Day	38% 9% 18% 30% 5%	4753
	21st to end	Day	52% 11% 15% 15% 8%	5919
April	1st to 10th	Day	54% 10% 16% 14% 6%	2400
	11th to 20th	Day	48% 10% 14% 17% 9% 2	2397
	21st to end	Day	47% 10% 16% 18% 8% 1	2735
May	1st to 10th	Day	35% 7% 12% 28% 17% 1	6320
	11th to 20th	Day	45% 8% 21% 21% 6%	6280
	21st to end	Day	43% 8% 19% 24% 6% 1	6968
June	1st to 10th	Day	48% 7% 14% 16% 11% 3	3016
	11th to 20th	Day	49% 9% 13% 19% 9% 1	3200
	21st to end	Day	36% 9% 18% 22% 13% 2	3200
July	1st to 10th	Day	19% 5% 11% 27% 25% 13%	6829
	11th to 20th	Day	16% 3 13% 29% 24% 14%	6294
	21st to end	Day	17% 4 17% 35% 20% 7%	6681
August	1st to 10th	Day	16% 6% 13% 32% 27% 6%	4524
	11th to 20th	Day	22% 6% 23% 33% 13% 2	4495
	21st to end	Day	28% 7% 22% 28% 13% 1	4353
September	1st to 10th	Day	27% 7% 17% 29% 17% 3	2317
	11th to 20th	Day	34% 9% 15% 23% 16% 2	2256
	21st to end	Day	39% 9% 21% 19% 11% 1	2076
October	1st to 10th	Day	39% 6% 24% 26% 6%	3180
	11th to 20th	Day	46% 8% 16% 25% 4	3049
	21st to end	Day	45% 8% 23% 20% 3	3101
November	1st to 10th	Day	58% 12% 13% 13% 3	1674
	11th to 20th	Day	58% 12% 16% 11% 3	1600
	21st to end	Day	57% 14% 18% 8% 3	1469
December	1st to 10th	Day	49% 15% 24% 12%	2290
	11th to 20th	Day	61% 16% 12% 8% 3	2644
	21st to end	Day	60% 13% 16% 9% 1	3359
January	1st to 10th	Night	68% 11% 14% 6% 1	6431
	11th to 20th	Night	48% 12% 20% 15% 5% 1	6320
	21st to end	Night	54% 12% 18% 14% 2	6952
February	1st to 10th	Night	60% 10% 13% 11% 5% 1	2760
	11th to 20th	Night	52% 9% 16% 16% 6% 1	2534
	21st to end	Night	56% 8% 18% 12% 6%	1996
March	1st to 10th	Night	41% 9% 21% 21% 8%	5376
	11th to 20th	Night	40% 8% 19% 26% 7%	5232
	21st to end	Night	52% 12% 14% 16% 6%	5055
April	1st to 10th	Night	43% 11% 23% 16% 6%	2000
	11th to 20th	Night	45% 9% 16% 19% 10% 1	1954
	21st to end	Night	43% 11% 15% 21% 10%	1662
May	1st to 10th	Night	33% 6% 15% 29% 17% 1	3637
	11th to 20th	Night	39% 8% 22% 25% 6%	3616
	21st to end	Night	33% 9% 23% 28% 5% 1	3890
June	1st to 10th	Night	41% 10% 14% 20% 11% 4	1379
	11th to 20th	Night	40% 11% 16% 22% 11%	1200
	21st to end	Night	31% 9% 21% 25% 11% 2	1200
July	1st to 10th	Night	18% 5% 15% 29% 22% 11%	3004
	11th to 20th	Night	17% 4 17% 25% 26% 12%	3538
	21st to end	Night	19% 3 16% 37% 17% 9%	3857
August	1st to 10th	Night	18% 5% 13% 32% 28% 4	2601
	11th to 20th	Night	21% 6% 27% 30% 15% 2	2615
	21st to end	Night	28% 6% 24% 26% 14% 2	3565
September	1st to 10th	Night	25% 7% 16% 31% 18% 4	1930
	11th to 20th	Night	31% 8% 14% 24% 20% 3	1923
	21st to end	Night	35% 11% 18% 24% 11% 2	2101
October	1st to 10th	Night	36% 6% 25% 23% 10% 1	3800
	11th to 20th	Night	43% 7% 20% 24% 7%	3884
	21st to end	Night	45% 8% 17% 26% 4	4457
November	1st to 10th	Night	55% 11% 16% 13% 6%	2625
	11th to 20th	Night	57% 12% 15% 10% 5%	2800
	21st to end	Night	61% 13% 15% 8% 3	2910
December	1st to 10th	Night	46% 16% 23% 14% 2	4890
	11th to 20th	Night	66% 13% 12% 7% 2	5547
	21st to end	Night	61% 12% 15% 9% 2	7599

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 10% 32% 24% 16% 6%	200
	11th to 20th	Day	16% 8% 27% 29% 17% 5%	200
	21st to end	Day	15% 7% 26% 35% 16% 2	220
February	1st to 10th	Day	16% 8% 41% 22% 11% 3	236
	11th to 20th	Day	13% 14% 28% 31% 11% 4	395
	21st to end	Day	14% 10% 33% 29% 10% 4	407
March	1st to 10th	Day	12% 15% 29% 27% 14% 3	500
	11th to 20th	Day	11% 16% 29% 23% 15% 6%	500
	21st to end	Day	16% 17% 27% 21% 14% 5%	550
April	1st to 10th	Day	17% 17% 28% 22% 13% 2	500
	11th to 20th	Day	15% 18% 26% 22% 12% 6%	492
	21st to end	Day	14% 13% 28% 26% 13% 6%	500
May	1st to 10th	Day	9% 14% 31% 29% 12% 4	503
	11th to 20th	Day	14% 9% 22% 31% 18% 7%	528
	21st to end	Day	13% 10% 23% 30% 18% 6%	598
June	1st to 10th	Day	15% 9% 25% 30% 18% 3	746
	11th to 20th	Day	14% 10% 28% 28% 16% 4	930
	21st to end	Day	8% 8% 23% 30% 23% 6%	930
July	1st to 10th	Day	8% 8% 22% 35% 22% 5%	779
	11th to 20th	Day	5% 9% 24% 31% 24% 7%	547
	21st to end	Day	3 6% 21% 35% 25% 8%	575
August	1st to 10th	Day	3 6% 19% 33% 27% 12%	527
	11th to 20th	Day	4 6% 23% 33% 22% 12%	517
	21st to end	Day	8% 8% 23% 26% 21% 12%	583
September	1st to 10th	Day	9% 9% 22% 30% 19% 11%	503
	11th to 20th	Day	9% 9% 24% 30% 23% 6%	490
	21st to end	Day	17% 12% 25% 26% 15% 5%	490
October	1st to 10th	Day	14% 9% 27% 26% 16% 8%	490
	11th to 20th	Day	16% 12% 27% 24% 15% 7%	429
	21st to end	Day	18% 8% 29% 31% 11% 3	330
November	1st to 10th	Day	16% 11% 30% 30% 11% 2	255
	11th to 20th	Day	19% 11% 32% 22% 13% 4	200
	21st to end	Day	17% 12% 26% 27% 15% 5%	200
December	1st to 10th	Day	12% 7% 28% 24% 23% 8%	200
	11th to 20th	Day	14% 10% 30% 30% 12% 6%	200
	21st to end	Day	14% 5% 30% 38% 10% 3	220
January	1st to 10th	Night	22% 7% 30% 29% 11% 1	829
	11th to 20th	Night	15% 6% 30% 35% 11% 2	800
	21st to end	Night	13% 6% 32% 33% 14% 2	880
February	1st to 10th	Night	19% 6% 29% 34% 11% 1	800
	11th to 20th	Night	13% 7% 26% 38% 15% 1	784
	21st to end	Night	16% 6% 23% 34% 20% 2	660
March	1st to 10th	Night	12% 8% 27% 32% 19% 3	800
	11th to 20th	Night	11% 8% 27% 33% 18% 2	800
	21st to end	Night	13% 6% 25% 34% 18% 4	880
April	1st to 10th	Night	12% 8% 20% 38% 19% 3	800
	11th to 20th	Night	11% 9% 24% 35% 19% 2	766
	21st to end	Night	12% 6% 27% 32% 19% 3	462
May	1st to 10th	Night	11% 4 20% 39% 23% 3	400
	11th to 20th	Night	11% 4 13% 42% 27% 4	394
	21st to end	Night	15% 5% 15% 30% 32% 5%	433
June	1st to 10th	Night	11% 4 20% 43% 21% 2	400
	11th to 20th	Night	12% 4 20% 41% 21% 3	400
	21st to end	Night	7% 5% 16% 42% 26% 6%	400
July	1st to 10th	Night	4 4 15% 37% 37% 3	390
	11th to 20th	Night	5% 3 14% 40% 34% 4	388
	21st to end	Night	5% 3 10% 41% 37% 5%	438
August	1st to 10th	Night	5% 2 8% 35% 42% 8%	398
	11th to 20th	Night	5% 2 8% 39% 42% 5%	397
	21st to end	Night	6% 4 13% 39% 34% 5%	850
September	1st to 10th	Night	7% 3 15% 37% 32% 5%	772
	11th to 20th	Night	10% 2 14% 32% 32% 9%	760
	21st to end	Night	14% 6% 16% 39% 21% 4	760
October	1st to 10th	Night	13% 4 18% 36% 25% 4	760
	11th to 20th	Night	15% 6% 22% 33% 21% 2	760
	21st to end	Night	18% 7% 29% 30% 12% 4	836
November	1st to 10th	Night	21% 8% 27% 33% 10% 1	780
	11th to 20th	Night	17% 9% 31% 27% 15% 2	800
	21st to end	Night	17% 8% 30% 30% 12% 3	910
December	1st to 10th	Night	16% 6% 28% 33% 14% 3	1000
	11th to 20th	Night	17% 7% 33% 30% 12% 1	1000
	21st to end	Night	19% 7% 33% 31% 9% 1	1115

Page generated at 2025-08-31 22:51:08. Version ac07

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