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 2024-04-03.

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% 4 8% 7% 4 6% 6% 6% 8% 35%	78750
	Night	8% 11% 5% 9% 8% 4 6% 6% 6% 7% 32%	81265
Transparency	Day	45% 10% 15% 18% 9% 2	78469
	Night	49% 11% 15% 16% 8% 1	81126
Seeing	Day	12% 11% 27% 28% 16% 5%	14484
	Night	14% 6% 24% 34% 20% 3	23170

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% 15% 7% 13% 10% 5% 8% 6% 6% 6% 15%	2417
	11th to 20th	Day	7% 14% 4 8% 10% 6% 8% 8% 8% 11% 16%	2516
	21st to end	Day	8% 15% 6% 13% 12% 6% 7% 6% 6% 6% 15%	2794
February	1st to 10th	Day	9% 13% 5% 10% 9% 6% 7% 6% 6% 6% 24%	1554
	11th to 20th	Day	4 11% 6% 9% 9% 5% 8% 5% 6% 7% 28%	1665
	21st to end	Day	6% 11% 6% 10% 9% 5% 7% 8% 7% 7% 24%	1553
March	1st to 10th	Day	4 9% 6% 10% 8% 5% 8% 7% 7% 9% 26%	1900
	11th to 20th	Day	5% 7% 3 9% 9% 6% 7% 7% 7% 7% 33%	1981
	21st to end	Day	6% 10% 5% 10% 9% 4 8% 7% 7% 8% 26%	2483
April	1st to 10th	Day	8% 10% 5% 8% 8% 5% 5% 7% 7% 9% 27%	2185
	11th to 20th	Day	7% 10% 4 9% 7% 5% 7% 6% 7% 9% 31%	2154
	21st to end	Day	7% 9% 4 8% 7% 5% 6% 6% 7% 9% 33%	2461
May	1st to 10th	Day	7% 8% 3 7% 6% 5% 6% 7% 6% 8% 37%	2520
	11th to 20th	Day	8% 6% 3 6% 7% 4 5% 6% 7% 9% 39%	2477
	21st to end	Day	11% 7% 3 7% 7% 4 6% 6% 7% 9% 33%	2745
June	1st to 10th	Day	13% 7% 3 8% 7% 5% 6% 5% 6% 7% 33%	2714
	11th to 20th	Day	14% 7% 3 7% 7% 4 7% 6% 6% 8% 30%	2880
	21st to end	Day	7% 5% 3 5% 5% 4 6% 6% 6% 9% 44%	2880
July	1st to 10th	Day	5% 4 2 4 4 4 5% 5% 7% 8% 52%	2753
	11th to 20th	Day	3 3 2 4 4 3 4 5% 6% 7% 58%	2543
	21st to end	Day	3 1 1 2 3 2 4 5% 5% 7% 68%	2741
August	1st to 10th	Day	3 2 1 4 4 3 4 5% 6% 9% 59%	2507
	11th to 20th	Day	4 3 1 3 4 3 4 4 6% 9% 59%	2471
	21st to end	Day	6% 4 2 5% 5% 4 6% 5% 7% 9% 48%	2404
September	1st to 10th	Day	5% 4 2 5% 5% 3 4 5% 5% 7% 55%	2160
	11th to 20th	Day	7% 4 3 6% 6% 3 6% 5% 6% 7% 47%	2138
	21st to end	Day	9% 7% 3 5% 5% 3 5% 5% 6% 8% 44%	1967
October	1st to 10th	Day	8% 8% 3 7% 7% 4 5% 5% 6% 6% 42%	1800
	11th to 20th	Day	10% 6% 4 6% 5% 4 6% 7% 7% 8% 37%	1743
	21st to end	Day	10% 11% 4 9% 7% 4 5% 5% 6% 9% 30%	1782
November	1st to 10th	Day	12% 12% 5% 9% 7% 4 8% 5% 7% 7% 24%	1589
	11th to 20th	Day	7% 11% 5% 10% 11% 5% 8% 6% 7% 7% 22%	1520
	21st to end	Day	9% 10% 6% 9% 11% 5% 7% 8% 7% 8% 20%	1396
December	1st to 10th	Day	6% 10% 5% 12% 11% 6% 9% 7% 7% 6% 20%	1330
	11th to 20th	Day	8% 10% 6% 13% 11% 6% 7% 7% 7% 7% 17%	1682
	21st to end	Day	7% 12% 6% 11% 12% 7% 8% 7% 6% 8% 16%	2345
January	1st to 10th	Night	11% 22% 6% 11% 8% 5% 7% 6% 6% 5% 12%	4503
	11th to 20th	Night	8% 13% 6% 12% 9% 5% 8% 8% 5% 8% 17%	4382
	21st to end	Night	9% 16% 8% 13% 11% 6% 6% 5% 5% 6% 15%	4862
February	1st to 10th	Night	11% 14% 6% 12% 8% 4 5% 6% 7% 8% 21%	2622
	11th to 20th	Night	7% 13% 5% 8% 8% 4 5% 4 5% 7% 33%	2402
	21st to end	Night	7% 12% 8% 10% 8% 4 7% 4 6% 8% 26%	1900
March	1st to 10th	Night	6% 12% 4 8% 7% 5% 7% 6% 7% 8% 29%	2280
	11th to 20th	Night	5% 8% 4 8% 7% 4 5% 6% 6% 8% 38%	2196
	21st to end	Night	7% 10% 5% 8% 7% 5% 6% 7% 6% 8% 32%	2114
April	1st to 10th	Night	6% 8% 3 6% 7% 4 6% 6% 8% 8% 37%	1820
	11th to 20th	Night	6% 9% 3 7% 8% 4 8% 6% 7% 7% 35%	1757
	21st to end	Night	8% 8% 4 7% 7% 5% 7% 6% 6% 7% 35%	1496
May	1st to 10th	Night	6% 8% 4 7% 7% 3 4 5% 6% 9% 41%	1440
	11th to 20th	Night	6% 6% 3 8% 5% 4 5% 7% 7% 11% 38%	1416
	21st to end	Night	11% 8% 4 6% 5% 3 5% 6% 6% 8% 39%	1526
June	1st to 10th	Night	9% 7% 3 7% 6% 4 5% 6% 6% 9% 37%	1242
	11th to 20th	Night	11% 5% 3 6% 7% 4 5% 7% 8% 9% 37%	1080
	21st to end	Night	3 4 2 6% 5% 4 7% 5% 6% 8% 50%	1080
July	1st to 10th	Night	3 3 2 5% 4 3 5% 4 6% 9% 56%	1203
	11th to 20th	Night	3 3 1 2 4 3 5% 4 8% 8% 60%	1412
	21st to end	Night	4 1 1 1 3 2 2 3 4 7% 73%	1576
August	1st to 10th	Night	3 2 1 3 3 3 3 4 5% 9% 64%	1432
	11th to 20th	Night	4 2 1 2 3 2 3 3 5% 7% 68%	1424
	21st to end	Night	4 3 1 4 4 3 5% 7% 6% 9% 54%	1952
September	1st to 10th	Night	4 4 1 4 5% 3 4 3 6% 7% 58%	1800
	11th to 20th	Night	8% 5% 2 5% 4 2 4 4 5% 7% 53%	1821
	21st to end	Night	8% 6% 2 6% 5% 3 4 6% 4 8% 47%	1990
October	1st to 10th	Night	9% 7% 3 5% 5% 3 5% 6% 6% 6% 45%	2160
	11th to 20th	Night	10% 8% 3 7% 6% 4 6% 5% 5% 7% 39%	2216
	21st to end	Night	10% 10% 4 8% 7% 4 5% 5% 5% 7% 35%	2574
November	1st to 10th	Night	13% 13% 4 8% 6% 4 5% 5% 6% 7% 28%	2490
	11th to 20th	Night	10% 10% 7% 10% 10% 5% 7% 7% 6% 6% 24%	2660
	21st to end	Night	9% 12% 7% 11% 9% 5% 7% 6% 7% 8% 19%	2764
December	1st to 10th	Night	8% 15% 6% 10% 8% 5% 8% 6% 6% 6% 21%	2850
	11th to 20th	Night	8% 17% 7% 14% 10% 5% 6% 6% 5% 7% 15%	3510
	21st to end	Night	8% 15% 6% 14% 13% 5% 7% 6% 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	52% 13% 17% 12% 5%	1900
	11th to 20th	Day	49% 12% 17% 18% 5%	1981
	21st to end	Day	55% 13% 17% 10% 5%	2483
April	1st to 10th	Day	55% 10% 16% 13% 5%	2185
	11th to 20th	Day	51% 10% 14% 15% 9% 1	2154
	21st to end	Day	48% 11% 15% 17% 8%	2461
May	1st to 10th	Day	43% 10% 16% 20% 10% 1	2520
	11th to 20th	Day	40% 11% 17% 22% 9%	2480
	21st to end	Day	48% 10% 16% 20% 7% 1	2746
June	1st to 10th	Day	50% 7% 15% 15% 9% 4	2714
	11th to 20th	Day	51% 10% 13% 17% 7% 1	2880
	21st to end	Day	36% 10% 17% 21% 13% 2	2880
July	1st to 10th	Day	29% 9% 13% 24% 18% 6%	2679
	11th to 20th	Day	26% 6% 15% 27% 21% 5%	2466
	21st to end	Day	16% 5% 13% 28% 30% 8%	2589
August	1st to 10th	Day	22% 8% 16% 27% 21% 7%	2490
	11th to 20th	Day	22% 8% 15% 30% 22% 4	2471
	21st to end	Day	31% 9% 15% 28% 15% 2	2404
September	1st to 10th	Day	28% 8% 17% 29% 16% 3	2160
	11th to 20th	Day	35% 9% 15% 22% 17% 3	2138
	21st to end	Day	39% 9% 20% 19% 11% 1	1967
October	1st to 10th	Day	42% 8% 18% 25% 7%	1800
	11th to 20th	Day	44% 12% 18% 21% 5%	1743
	21st to end	Day	51% 12% 17% 16% 4	1782
November	1st to 10th	Day	58% 12% 13% 13% 4	1589
	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	51% 11% 18% 12% 8%	2280
	11th to 20th	Night	43% 13% 17% 20% 7%	2197
	21st to end	Night	50% 12% 16% 17% 5%	2114
April	1st to 10th	Night	42% 11% 23% 17% 7%	1820
	11th to 20th	Night	46% 9% 17% 18% 9% 1	1757
	21st to end	Night	45% 11% 15% 20% 10%	1496
May	1st to 10th	Night	41% 8% 18% 21% 11% 1	1440
	11th to 20th	Night	37% 11% 19% 23% 10%	1416
	21st to end	Night	42% 10% 18% 22% 8%	1526
June	1st to 10th	Night	42% 10% 15% 20% 9% 4	1242
	11th to 20th	Night	40% 12% 16% 23% 9%	1080
	21st to end	Night	31% 10% 20% 25% 11% 3	1080
July	1st to 10th	Night	24% 9% 15% 27% 19% 7%	1168
	11th to 20th	Night	22% 7% 16% 28% 23% 4	1366
	21st to end	Night	13% 4 13% 30% 30% 9%	1488
August	1st to 10th	Night	20% 6% 14% 28% 25% 7%	1424
	11th to 20th	Night	17% 6% 15% 33% 25% 4	1424
	21st to end	Night	25% 9% 16% 31% 17% 3	1952
September	1st to 10th	Night	26% 8% 16% 29% 18% 3	1800
	11th to 20th	Night	31% 8% 14% 23% 20% 3	1821
	21st to end	Night	35% 11% 17% 24% 11% 2	1990
October	1st to 10th	Night	39% 9% 17% 26% 9%	2160
	11th to 20th	Night	44% 9% 16% 22% 9%	2216
	21st to end	Night	48% 10% 16% 21% 5%	2574
November	1st to 10th	Night	56% 10% 15% 13% 6%	2490
	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% 17% 28% 22% 12% 2	429
	11th to 20th	Day	17% 18% 28% 18% 12% 7%	412
	21st to end	Day	15% 14% 31% 25% 11% 5%	420
May	1st to 10th	Day	10% 15% 31% 29% 11% 3	423
	11th to 20th	Day	13% 9% 23% 30% 17% 8%	448
	21st to end	Day	14% 9% 21% 29% 19% 7%	507
June	1st to 10th	Day	16% 9% 26% 29% 17% 2	644
	11th to 20th	Day	15% 11% 30% 27% 14% 3	810
	21st to end	Day	8% 8% 25% 30% 22% 7%	810
July	1st to 10th	Day	8% 8% 23% 35% 21% 5%	674
	11th to 20th	Day	6% 10% 26% 31% 22% 5%	465
	21st to end	Day	3 7% 22% 35% 25% 7%	487
August	1st to 10th	Day	4 7% 20% 33% 25% 10%	447
	11th to 20th	Day	4 7% 23% 36% 19% 11%	437
	21st to end	Day	8% 9% 26% 27% 19% 10%	495
September	1st to 10th	Day	10% 10% 24% 32% 18% 7%	450
	11th to 20th	Day	9% 10% 25% 29% 22% 6%	450
	21st to end	Day	18% 12% 24% 25% 15% 6%	450
October	1st to 10th	Day	15% 10% 27% 24% 16% 8%	450
	11th to 20th	Day	15% 13% 27% 23% 16% 6%	393
	21st to end	Day	19% 9% 29% 30% 11% 3	297
November	1st to 10th	Day	17% 11% 31% 28% 12% 2	230
	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% 7% 24% 34% 18% 4	836
April	1st to 10th	Night	11% 8% 20% 36% 21% 3	728
	11th to 20th	Night	11% 9% 23% 35% 19% 2	689
	21st to end	Night	13% 5% 27% 34% 17% 3	416
May	1st to 10th	Night	11% 4 19% 39% 24% 2	360
	11th to 20th	Night	10% 5% 11% 43% 27% 4	354
	21st to end	Night	15% 5% 14% 28% 33% 5%	389
June	1st to 10th	Night	12% 4 21% 42% 21% 2	360
	11th to 20th	Night	13% 3 19% 40% 22% 3	360
	21st to end	Night	6% 5% 15% 42% 26% 6%	360
July	1st to 10th	Night	4 4 13% 36% 39% 4	350
	11th to 20th	Night	5% 3 15% 39% 33% 4	348
	21st to end	Night	5% 2 10% 41% 38% 5%	394
August	1st to 10th	Night	5% 2 8% 33% 43% 9%	358
	11th to 20th	Night	5% 1 7% 38% 44% 4	356
	21st to end	Night	7% 4 13% 37% 34% 5%	764
September	1st to 10th	Night	8% 3 16% 37% 30% 5%	720
	11th to 20th	Night	11% 2 14% 31% 33% 9%	720
	21st to end	Night	14% 6% 15% 38% 22% 5%	720
October	1st to 10th	Night	13% 4 17% 35% 26% 4	720
	11th to 20th	Night	15% 7% 22% 33% 21% 3	720
	21st to end	Night	18% 7% 30% 29% 12% 4	792
November	1st to 10th	Night	22% 8% 27% 32% 10% 1	740
	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 2024-03-31 03:08:55. Version ac07

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