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 2024-11-04.

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	7% 8% 3 8% 6% 5% 5% 4 6% 8% 39%	105679
	Night	7% 10% 4 9% 6% 5% 5% 4 6% 7% 36%	101849
Transparency	Day	41% 9% 16% 20% 11% 3	105440
	Night	45% 10% 16% 18% 9% 2	101734
Seeing	Day	12% 11% 27% 28% 17% 6%	15391
	Night	14% 6% 23% 34% 20% 3	23789

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% 16% 7% 15% 9% 7% 7% 4 6% 6% 15%	2417
	11th to 20th	Day	7% 15% 4 10% 8% 8% 7% 6% 8% 10% 16%	2516
	21st to end	Day	8% 15% 6% 15% 11% 8% 6% 4 6% 6% 15%	2794
February	1st to 10th	Day	8% 15% 4 11% 8% 7% 6% 5% 6% 6% 24%	1554
	11th to 20th	Day	4 13% 5% 11% 8% 8% 7% 4 7% 7% 28%	1665
	21st to end	Day	6% 14% 4 12% 8% 7% 7% 6% 7% 7% 23%	1553
March	1st to 10th	Day	4 11% 6% 12% 8% 7% 7% 5% 7% 8% 25%	3138
	11th to 20th	Day	3 6% 2 8% 6% 5% 5% 4 6% 7% 47%	3321
	21st to end	Day	6% 12% 4 11% 8% 7% 7% 5% 7% 8% 26%	4128
April	1st to 10th	Day	8% 11% 4 9% 7% 6% 5% 6% 8% 9% 27%	2280
	11th to 20th	Day	7% 10% 3 10% 7% 5% 6% 5% 7% 8% 32%	2276
	21st to end	Day	7% 10% 4 10% 6% 6% 6% 4 7% 9% 32%	2598
May	1st to 10th	Day	6% 7% 3 8% 5% 5% 5% 4 6% 8% 41%	4420
	11th to 20th	Day	7% 7% 4 8% 6% 5% 5% 5% 7% 11% 37%	4377
	21st to end	Day	12% 10% 4 10% 7% 6% 6% 5% 7% 8% 25%	4863
June	1st to 10th	Day	12% 8% 3 9% 6% 6% 5% 4 6% 7% 33%	2865
	11th to 20th	Day	13% 8% 3 8% 6% 6% 6% 5% 7% 8% 31%	3040
	21st to end	Day	7% 5% 2 6% 4 5% 6% 4 6% 9% 44%	3040
July	1st to 10th	Day	3 3 1 3 3 4 4 3 5% 6% 63%	4821
	11th to 20th	Day	2 2 1 3 3 3 3 2 4 6% 72%	4457
	21st to end	Day	4 2 1 3 2 2 3 3 5% 8% 65%	4790
August	1st to 10th	Day	2 1 1 3 2 3 4 4 7% 8% 65%	4401
	11th to 20th	Day	2 2 1 4 3 4 5% 4 7% 9% 57%	4313
	21st to end	Day	6% 4 1 5% 4 4 5% 3 7% 8% 53%	4221
September	1st to 10th	Day	5% 4 2 6% 4 3 4 4 5% 8% 56%	2280
	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% 23%	1616
	11th to 20th	Day	7% 12% 4 12% 10% 7% 7% 4 7% 7% 22%	1520
	21st to end	Day	9% 12% 4 11% 9% 6% 7% 6% 7% 8% 20%	1396
December	1st to 10th	Day	6% 12% 4 13% 11% 9% 8% 5% 7% 6% 20%	1330
	11th to 20th	Day	7% 11% 6% 15% 10% 8% 7% 5% 7% 7% 17%	1682
	21st to end	Day	7% 13% 6% 13% 10% 8% 8% 6% 6% 7% 16%	2345
January	1st to 10th	Night	11% 22% 6% 12% 7% 7% 7% 5% 6% 5% 12%	4503
	11th to 20th	Night	8% 14% 5% 14% 8% 7% 8% 6% 5% 8% 17%	4382
	21st to end	Night	9% 17% 7% 15% 9% 7% 6% 3 6% 5% 15%	4862
February	1st to 10th	Night	10% 15% 5% 13% 7% 5% 6% 4 7% 7% 21%	2622
	11th to 20th	Night	6% 14% 5% 10% 7% 5% 5% 3 5% 7% 32%	2402
	21st to end	Night	7% 14% 6% 12% 6% 6% 6% 4 6% 8% 26%	1900
March	1st to 10th	Night	4 10% 4 9% 7% 7% 7% 5% 8% 10% 29%	3736
	11th to 20th	Night	4 7% 3 7% 5% 4 4 4 5% 8% 49%	3656
	21st to end	Night	7% 11% 4 10% 6% 6% 6% 5% 7% 8% 30%	3524
April	1st to 10th	Night	7% 9% 3 8% 6% 5% 6% 4 8% 8% 35%	1900
	11th to 20th	Night	6% 9% 3 8% 7% 6% 7% 5% 7% 7% 35%	1855
	21st to end	Night	8% 9% 3 8% 7% 6% 6% 5% 7% 7% 35%	1579
May	1st to 10th	Night	5% 8% 3 8% 6% 5% 4 4 6% 9% 42%	2540
	11th to 20th	Night	6% 6% 3 7% 5% 5% 5% 5% 6% 10% 42%	2516
	21st to end	Night	8% 8% 3 7% 5% 5% 6% 6% 8% 8% 36%	2708
June	1st to 10th	Night	8% 8% 3 8% 6% 6% 5% 5% 6% 8% 37%	1310
	11th to 20th	Night	10% 6% 2 7% 6% 5% 4 6% 8% 9% 37%	1140
	21st to end	Night	3 4 2 7% 4 5% 5% 5% 6% 8% 50%	1140
July	1st to 10th	Night	2 2 1 4 2 4 4 3 6% 7% 66%	2121
	11th to 20th	Night	2 2 1 2 2 2 3 2 5% 6% 73%	2498
	21st to end	Night	3 2 1 2 3 2 3 3 5% 7% 69%	2762
August	1st to 10th	Night	2 1 1 2 3 3 5% 4 7% 8% 64%	2529
	11th to 20th	Night	3 2 1 3 3 4 4 4 6% 10% 61%	2511
	21st to end	Night	6% 4 2 5% 3 4 4 4 6% 7% 54%	3456
September	1st to 10th	Night	4 4 1 5% 4 4 4 3 7% 7% 59%	1900
	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	13% 14% 4 9% 5% 6% 5% 4 6% 6% 28%	2535
	11th to 20th	Night	10% 12% 5% 11% 9% 6% 6% 5% 6% 6% 24%	2660
	21st to end	Night	9% 15% 5% 13% 7% 6% 7% 5% 7% 7% 19%	2764
December	1st to 10th	Night	8% 17% 5% 11% 8% 7% 7% 5% 7% 6% 21%	2850
	11th to 20th	Night	7% 18% 7% 16% 9% 6% 5% 5% 5% 6% 15%	3510
	21st to end	Night	7% 15% 6% 16% 11% 7% 7% 5% 6% 6% 15%	5313

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	66% 14% 11% 9% 1	2417
	11th to 20th	Day	56% 9% 18% 11% 2 4	2540
	21st to end	Day	67% 12% 12% 7% 1	2794
February	1st to 10th	Day	60% 11% 12% 11% 5% 1	1554
	11th to 20th	Day	54% 12% 17% 12% 5%	1674
	21st to end	Day	58% 12% 15% 11% 4	1553
March	1st to 10th	Day	53% 11% 13% 16% 7%	3138
	11th to 20th	Day	34% 11% 21% 30% 4	3321
	21st to end	Day	54% 13% 14% 11% 8%	4128
April	1st to 10th	Day	55% 11% 16% 14% 5%	2280
	11th to 20th	Day	49% 10% 14% 16% 9% 1	2276
	21st to end	Day	48% 11% 15% 17% 9% 1	2598
May	1st to 10th	Day	38% 9% 15% 25% 13% 1	4420
	11th to 20th	Day	39% 10% 20% 23% 8%	4380
	21st to end	Day	54% 10% 16% 16% 4	4864
June	1st to 10th	Day	50% 7% 15% 15% 9% 3	2865
	11th to 20th	Day	50% 10% 13% 18% 8% 1	3040
	21st to end	Day	36% 10% 17% 21% 13% 2	3040
July	1st to 10th	Day	21% 7% 10% 20% 27% 16%	4747
	11th to 20th	Day	16% 3 8% 21% 32% 20%	4380
	21st to end	Day	18% 4 12% 32% 24% 10%	4639
August	1st to 10th	Day	16% 6% 12% 32% 28% 6%	4384
	11th to 20th	Day	22% 6% 24% 33% 13% 2	4355
	21st to end	Day	28% 7% 22% 28% 13% 1	4220
September	1st to 10th	Day	27% 7% 17% 29% 16% 3	2280
	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	59% 12% 13% 13% 3	1616
	11th to 20th	Day	58% 13% 16% 10% 3	1520
	21st to end	Day	57% 13% 18% 8% 3	1396
December	1st to 10th	Day	59% 12% 13% 15% 1	1330
	11th to 20th	Day	60% 17% 13% 8% 3	1684
	21st to end	Day	59% 15% 15% 10% 2	2345
January	1st to 10th	Night	69% 12% 12% 6% 2	4503
	11th to 20th	Night	60% 9% 13% 14% 3 1	4420
	21st to end	Night	67% 13% 11% 7% 2	4862
February	1st to 10th	Night	60% 10% 14% 10% 5% 1	2622
	11th to 20th	Night	52% 9% 15% 17% 6% 1	2404
	21st to end	Night	57% 8% 17% 12% 7%	1900
March	1st to 10th	Night	46% 10% 17% 17% 9%	3736
	11th to 20th	Night	34% 10% 21% 30% 5%	3657
	21st to end	Night	49% 12% 14% 16% 8%	3524
April	1st to 10th	Night	43% 11% 23% 16% 6%	1900
	11th to 20th	Night	46% 9% 16% 18% 10% 1	1855
	21st to end	Night	45% 11% 15% 19% 10%	1579
May	1st to 10th	Night	38% 7% 15% 27% 13% 1	2540
	11th to 20th	Night	33% 10% 23% 25% 9%	2516
	21st to end	Night	42% 12% 19% 21% 5%	2708
June	1st to 10th	Night	42% 10% 15% 19% 10% 4	1310
	11th to 20th	Night	40% 12% 16% 22% 10%	1140
	21st to end	Night	30% 10% 20% 26% 12% 2	1140
July	1st to 10th	Night	16% 7% 11% 29% 25% 12%	2086
	11th to 20th	Night	14% 4 10% 19% 35% 17%	2452
	21st to end	Night	16% 3 12% 34% 22% 12%	2674
August	1st to 10th	Night	17% 5% 12% 32% 29% 4	2521
	11th to 20th	Night	20% 6% 27% 30% 15% 2	2535
	21st to end	Night	28% 6% 25% 26% 13% 1	3456
September	1st to 10th	Night	25% 7% 16% 30% 18% 4	1900
	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% 10% 15% 13% 6%	2535
	11th to 20th	Night	57% 13% 15% 10% 6%	2660
	21st to end	Night	61% 13% 15% 8% 3	2764
December	1st to 10th	Night	58% 10% 15% 13% 3	2850
	11th to 20th	Night	65% 15% 12% 6% 2	3507
	21st to end	Night	62% 14% 15% 7% 2	5313

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% 33% 23% 16% 6%	180
	11th to 20th	Day	17% 9% 28% 27% 14% 5%	180
	21st to end	Day	15% 7% 28% 33% 14% 2	198
February	1st to 10th	Day	17% 8% 43% 23% 8%	214
	11th to 20th	Day	12% 15% 29% 31% 9% 4	365
	21st to end	Day	14% 10% 33% 28% 10% 4	375
March	1st to 10th	Day	13% 16% 30% 26% 12% 3	460
	11th to 20th	Day	12% 17% 28% 22% 16% 6%	460
	21st to end	Day	16% 19% 27% 20% 15% 5%	506
April	1st to 10th	Day	18% 18% 28% 22% 12% 1	460
	11th to 20th	Day	15% 19% 27% 20% 12% 7%	452
	21st to end	Day	15% 14% 30% 25% 11% 4	460
May	1st to 10th	Day	10% 15% 31% 29% 11% 4	463
	11th to 20th	Day	13% 9% 23% 31% 17% 7%	488
	21st to end	Day	14% 10% 23% 29% 18% 6%	553
June	1st to 10th	Day	16% 10% 26% 29% 17% 2	695
	11th to 20th	Day	15% 11% 29% 27% 15% 3	870
	21st to end	Day	8% 9% 24% 31% 22% 6%	870
July	1st to 10th	Day	8% 8% 22% 35% 22% 6%	726
	11th to 20th	Day	5% 9% 25% 31% 23% 7%	506
	21st to end	Day	4 7% 22% 35% 25% 7%	531
August	1st to 10th	Day	3 7% 19% 33% 26% 11%	487
	11th to 20th	Day	4 6% 22% 34% 21% 13%	477
	21st to end	Day	9% 9% 25% 27% 20% 10%	539
September	1st to 10th	Day	9% 9% 23% 30% 19% 10%	490
	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% 31% 29% 11% 2	239
	11th to 20th	Day	18% 12% 31% 22% 13% 4	180
	21st to end	Day	17% 12% 27% 26% 16% 3	180
December	1st to 10th	Day	12% 8% 29% 22% 22% 7%	180
	11th to 20th	Day	13% 10% 32% 27% 12% 6%	180
	21st to end	Day	15% 5% 32% 37% 10% 2	198
January	1st to 10th	Night	23% 7% 30% 27% 11% 1	787
	11th to 20th	Night	16% 7% 30% 34% 12% 2	760
	21st to end	Night	14% 6% 32% 31% 14% 2	836
February	1st to 10th	Night	19% 6% 29% 33% 11% 1	760
	11th to 20th	Night	13% 7% 26% 38% 15% 1	744
	21st to end	Night	15% 6% 22% 33% 21% 2	628
March	1st to 10th	Night	12% 9% 27% 31% 18% 3	760
	11th to 20th	Night	11% 8% 27% 33% 19% 2	760
	21st to end	Night	13% 6% 25% 34% 18% 4	836
April	1st to 10th	Night	12% 9% 20% 37% 19% 3	760
	11th to 20th	Night	11% 9% 23% 35% 19% 3	727
	21st to end	Night	13% 6% 27% 33% 18% 3	439
May	1st to 10th	Night	12% 4 19% 39% 24% 3	380
	11th to 20th	Night	11% 5% 11% 42% 28% 4	374
	21st to end	Night	15% 5% 14% 29% 32% 5%	411
June	1st to 10th	Night	12% 4 21% 41% 21% 2	380
	11th to 20th	Night	13% 3 20% 40% 21% 3	380
	21st to end	Night	6% 5% 16% 42% 26% 6%	380
July	1st to 10th	Night	4 4 14% 37% 38% 4	370
	11th to 20th	Night	5% 3 14% 40% 34% 4	368
	21st to end	Night	5% 2 10% 41% 37% 5%	416
August	1st to 10th	Night	5% 2 8% 34% 42% 8%	378
	11th to 20th	Night	5% 1 7% 38% 44% 5%	377
	21st to end	Night	7% 4 13% 38% 33% 5%	807
September	1st to 10th	Night	7% 3 15% 37% 32% 5%	760
	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	22% 8% 27% 32% 10% 1	754
	11th to 20th	Night	17% 9% 32% 26% 14% 2	760
	21st to end	Night	18% 8% 30% 30% 12% 3	864
December	1st to 10th	Night	16% 7% 29% 32% 14% 3	950
	11th to 20th	Night	17% 7% 33% 31% 11% 1	950
	21st to end	Night	19% 7% 33% 31% 9% 1	1057

Page generated at 2024-11-01 19:47:30. Version ac07

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