Upper Kananaskis Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Upper Kananaskis Lake clear sky chart from 2005-11-06 to 2025-07-21.

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	5% 11% 4 11% 7% 6% 6% 5% 6% 8% 31%	124030
	Night	3 9% 4 11% 8% 7% 7% 5% 7% 9% 31%	123791
Transparency	Day	24% 45% 11% 12% 7% 1	123784
	Night	23% 45% 13% 12% 7% 1	123680
Seeing	Day	18% 22% 31% 20% 8% 2	16176
	Night	11% 21% 35% 23% 9% 1	25203

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	3 4 16% 13% 10% 10% 6% 8% 8% 22%	3179
	11th to 20th	Day	4 5% 14% 8% 8% 7% 5% 6% 9% 33%	3414
	21st to end	Day	9% 3 10% 7% 6% 6% 6% 8% 8% 36%	4004
February	1st to 10th	Day	10% 6% 14% 9% 12% 9% 6% 9% 7% 19%	1600
	11th to 20th	Day	1 8% 7% 18% 10% 8% 6% 5% 7% 10% 20%	1725
	21st to end	Day	1 8% 5% 18% 13% 9% 8% 6% 6% 7% 18%	1650
March	1st to 10th	Day	8% 5% 18% 11% 6% 5% 5% 6% 7% 28%	4518
	11th to 20th	Day	1 9% 9% 17% 8% 7% 7% 4 5% 6% 27%	4858
	21st to end	Day	1 19% 10% 19% 9% 7% 6% 4 5% 5% 14%	5695
April	1st to 10th	Day	4 16% 9% 19% 9% 5% 6% 4 5% 5% 17%	2405
	11th to 20th	Day	3 18% 8% 16% 8% 6% 5% 4 6% 7% 19%	2570
	21st to end	Day	6% 21% 7% 13% 7% 5% 5% 4 6% 6% 21%	2600
May	1st to 10th	Day	9% 20% 4 7% 4 4 4 4 4 6% 34%	6183
	11th to 20th	Day	8% 19% 6% 12% 7% 6% 6% 5% 6% 8% 18%	6642
	21st to end	Day	8% 18% 4 9% 6% 4 5% 4 6% 7% 30%	7405
June	1st to 10th	Day	15% 14% 4 8% 6% 5% 4 4 7% 7% 27%	3000
	11th to 20th	Day	18% 14% 4 10% 6% 5% 6% 5% 6% 6% 21%	3000
	21st to end	Day	10% 8% 3 11% 7% 6% 6% 5% 6% 7% 31%	3000
July	1st to 10th	Day	6% 5% 2 8% 4 5% 6% 4 6% 7% 45%	4890
	11th to 20th	Day	6% 4 2 6% 4 5% 5% 5% 6% 8% 50%	4890
	21st to end	Day	3 4 1 6% 5% 5% 5% 4 6% 8% 52%	4865
August	1st to 10th	Day	10% 6% 3 9% 6% 5% 6% 4 6% 7% 38%	4401
	11th to 20th	Day	8% 6% 2 8% 5% 6% 6% 4 8% 9% 39%	4123
	21st to end	Day	8% 7% 2 7% 4 5% 5% 5% 6% 9% 43%	4521
September	1st to 10th	Day	10% 9% 3 8% 5% 4 4 4 5% 7% 42%	2305
	11th to 20th	Day	10% 11% 4 7% 6% 5% 5% 4 5% 9% 34%	2112
	21st to end	Day	6% 11% 3 8% 7% 6% 6% 5% 5% 8% 36%	2090
October	1st to 10th	Day	6% 10% 3 8% 6% 5% 5% 3 6% 8% 41%	3414
	11th to 20th	Day	2 8% 3 8% 6% 5% 8% 7% 9% 11% 33%	2842
	21st to end	Day	2 9% 4 10% 6% 6% 7% 6% 8% 8% 32%	3101
November	1st to 10th	Day	2 14% 6% 16% 8% 7% 9% 5% 6% 8% 19%	1710
	11th to 20th	Day	1 8% 4 12% 9% 8% 8% 7% 8% 11% 24%	1488
	21st to end	Day	11% 4 12% 8% 7% 7% 5% 8% 10% 28%	1400
December	1st to 10th	Day	5% 3 12% 7% 6% 6% 6% 9% 10% 33%	2290
	11th to 20th	Day	1 6% 5% 12% 9% 7% 10% 9% 10% 10% 22%	2642
	21st to end	Day	7% 4 12% 8% 9% 8% 6% 8% 9% 29%	3498
January	1st to 10th	Night	6% 6% 21% 13% 11% 10% 5% 6% 6% 15%	6766
	11th to 20th	Night	4 3 11% 9% 8% 8% 6% 10% 10% 30%	6529
	21st to end	Night	1 10% 4 11% 9% 7% 7% 5% 7% 9% 31%	6952
February	1st to 10th	Night	1 7% 5% 13% 13% 10% 10% 6% 8% 7% 19%	2800
	11th to 20th	Night	7% 5% 18% 9% 8% 7% 6% 8% 10% 21%	2561
	21st to end	Night	7% 5% 14% 12% 9% 9% 6% 8% 8% 23%	1980
March	1st to 10th	Night	7% 6% 16% 10% 8% 6% 5% 7% 9% 25%	5376
	11th to 20th	Night	1 8% 7% 13% 7% 6% 7% 6% 8% 8% 29%	5140
	21st to end	Night	1 14% 9% 17% 8% 7% 7% 6% 7% 8% 17%	5280
April	1st to 10th	Night	3 14% 7% 13% 8% 6% 6% 5% 7% 10% 23%	1995
	11th to 20th	Night	2 13% 6% 15% 6% 5% 5% 5% 8% 8% 27%	1781
	21st to end	Night	3 16% 5% 12% 7% 6% 5% 4 6% 6% 31%	1800
May	1st to 10th	Night	6% 16% 6% 8% 4 4 3 3 4 5% 40%	3780
	11th to 20th	Night	5% 13% 6% 11% 6% 5% 6% 4 7% 8% 28%	3236
	21st to end	Night	9% 16% 4 8% 5% 4 4 4 5% 7% 35%	3470
June	1st to 10th	Night	13% 14% 3 7% 5% 5% 6% 4 6% 7% 31%	1400
	11th to 20th	Night	15% 15% 3 8% 5% 5% 4 4 5% 8% 28%	1400
	21st to end	Night	9% 6% 2 7% 6% 6% 6% 5% 7% 7% 38%	1400
July	1st to 10th	Night	5% 6% 2 8% 5% 5% 4 4 5% 6% 50%	2290
	11th to 20th	Night	4 4 1 4 3 4 4 3 7% 8% 57%	2290
	21st to end	Night	2 4 1 4 3 3 4 4 5% 7% 64%	2685
August	1st to 10th	Night	6% 9% 3 7% 5% 5% 5% 5% 7% 8% 41%	2529
	11th to 20th	Night	5% 5% 1 5% 4 5% 4 4 8% 9% 49%	2710
	21st to end	Night	7% 6% 1 5% 4 4 4 4 7% 9% 49%	3146
September	1st to 10th	Night	6% 7% 3 6% 4 4 5% 4 5% 8% 48%	1871
	11th to 20th	Night	9% 11% 3 7% 5% 4 4 4 6% 7% 41%	2067
	21st to end	Night	6% 10% 2 7% 5% 5% 4 4 8% 8% 40%	2090
October	1st to 10th	Night	4 9% 3 8% 5% 5% 5% 5% 6% 9% 40%	3550
	11th to 20th	Night	2 7% 3 7% 5% 6% 7% 4 7% 10% 41%	4085
	21st to end	Night	2 9% 5% 11% 6% 6% 7% 7% 7% 10% 29%	4457
November	1st to 10th	Night	2 13% 7% 14% 9% 9% 7% 5% 7% 10% 18%	2567
	11th to 20th	Night	1 8% 4 12% 10% 10% 9% 7% 9% 9% 21%	2910
	21st to end	Night	1 10% 4 14% 10% 7% 8% 5% 9% 9% 22%	3000
December	1st to 10th	Night	6% 3 9% 8% 7% 8% 6% 9% 11% 33%	4890
	11th to 20th	Night	4 5% 15% 10% 11% 11% 8% 10% 10% 16%	5550
	21st to end	Night	8% 5% 13% 10% 9% 8% 6% 9% 9% 22%	7458

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	31% 35% 15% 10% 7% 1	3179
	11th to 20th	Day	30% 31% 12% 11% 12% 3	3437
	21st to end	Day	19% 39% 18% 15% 10%	4004
February	1st to 10th	Day	18% 67% 7% 3 4 1	1600
	11th to 20th	Day	18% 65% 8% 5% 3 1	1734
	21st to end	Day	19% 65% 7% 4 4 1	1650
March	1st to 10th	Day	27% 34% 15% 8% 15% 1	4518
	11th to 20th	Day	27% 36% 17% 13% 5%	4859
	21st to end	Day	43% 36% 9% 5% 5%	5695
April	1st to 10th	Day	22% 66% 7% 4 1	2405
	11th to 20th	Day	20% 65% 8% 5% 2	2570
	21st to end	Day	23% 63% 6% 5% 2	2600
May	1st to 10th	Day	32% 31% 9% 18% 10%	6183
	11th to 20th	Day	39% 38% 11% 11% 1	6646
	21st to end	Day	24% 36% 20% 16% 4	7406
June	1st to 10th	Day	14% 64% 9% 9% 3	3000
	11th to 20th	Day	20% 63% 5% 8% 4	3000
	21st to end	Day	21% 64% 5% 6% 4 1	3000
July	1st to 10th	Day	19% 38% 6% 12% 22% 3	4816
	11th to 20th	Day	16% 38% 8% 20% 16% 2	4809
	21st to end	Day	15% 38% 7% 15% 21% 4	4711
August	1st to 10th	Day	24% 42% 6% 16% 10% 1	4384
	11th to 20th	Day	25% 42% 12% 17% 4	4164
	21st to end	Day	19% 40% 13% 20% 7%	4520
September	1st to 10th	Day	17% 63% 6% 9% 4 1	2305
	11th to 20th	Day	20% 63% 6% 6% 4	2112
	21st to end	Day	20% 63% 7% 6% 4 1	2090
October	1st to 10th	Day	19% 42% 14% 19% 6%	3414
	11th to 20th	Day	18% 43% 17% 12% 10%	2842
	21st to end	Day	19% 42% 13% 20% 6%	3101
November	1st to 10th	Day	23% 63% 6% 5% 2	1710
	11th to 20th	Day	15% 65% 10% 6% 4 1	1488
	21st to end	Day	17% 63% 9% 6% 4 2	1400
December	1st to 10th	Day	21% 45% 21% 10% 3	2290
	11th to 20th	Day	26% 41% 19% 11% 3	2644
	21st to end	Day	24% 35% 14% 15% 10% 3	3498
January	1st to 10th	Night	37% 37% 14% 8% 4 1	6766
	11th to 20th	Night	26% 33% 14% 11% 10% 7%	6568
	21st to end	Night	23% 40% 15% 12% 9%	6952
February	1st to 10th	Night	19% 65% 6% 4 5% 1	2800
	11th to 20th	Night	16% 66% 9% 4 4 1	2562
	21st to end	Night	17% 64% 6% 6% 6% 1	1980
March	1st to 10th	Night	27% 36% 16% 9% 9% 2	5376
	11th to 20th	Night	23% 34% 17% 18% 8% 1	5140
	21st to end	Night	38% 37% 13% 7% 5%	5280
April	1st to 10th	Night	16% 67% 9% 6% 3	1995
	11th to 20th	Night	14% 65% 10% 8% 3	1781
	21st to end	Night	21% 64% 4 7% 4	1800
May	1st to 10th	Night	29% 31% 9% 20% 10%	3777
	11th to 20th	Night	35% 34% 10% 19% 2	3236
	21st to end	Night	22% 38% 18% 16% 6%	3470
June	1st to 10th	Night	13% 65% 7% 12% 4	1400
	11th to 20th	Night	17% 65% 6% 6% 6%	1400
	21st to end	Night	17% 63% 6% 8% 6% 1	1400
July	1st to 10th	Night	19% 39% 7% 12% 18% 4	2255
	11th to 20th	Night	12% 38% 9% 23% 16% 2	2248
	21st to end	Night	11% 37% 8% 17% 20% 7%	2600
August	1st to 10th	Night	24% 42% 9% 19% 5% 1	2521
	11th to 20th	Night	19% 41% 18% 16% 5%	2735
	21st to end	Night	18% 40% 21% 17% 4	3146
September	1st to 10th	Night	15% 63% 7% 10% 3 1	1871
	11th to 20th	Night	18% 63% 5% 9% 5%	2067
	21st to end	Night	17% 63% 8% 9% 3	2090
October	1st to 10th	Night	20% 43% 12% 16% 10%	3550
	11th to 20th	Night	15% 43% 14% 21% 7%	4085
	21st to end	Night	17% 44% 14% 20% 5%	4457
November	1st to 10th	Night	22% 63% 8% 4 4	2567
	11th to 20th	Night	16% 65% 11% 5% 3 1	2910
	21st to end	Night	17% 62% 9% 6% 4 2	3000
December	1st to 10th	Night	16% 48% 24% 9% 3	4890
	11th to 20th	Night	30% 45% 15% 6% 4	5547
	21st to end	Night	28% 36% 15% 10% 7% 3	7458

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	15% 22% 33% 21% 7% 4	200
	11th to 20th	Day	14% 24% 40% 19% 4 1	200
	21st to end	Day	13% 35% 35% 11% 4 2	220
February	1st to 10th	Day	21% 28% 32% 14% 7%	200
	11th to 20th	Day	12% 20% 42% 18% 7%	295
	21st to end	Day	21% 23% 32% 18% 5%	414
March	1st to 10th	Day	17% 30% 30% 16% 5% 2	500
	11th to 20th	Day	12% 30% 35% 16% 6% 2	500
	21st to end	Day	18% 30% 29% 17% 5% 2	550
April	1st to 10th	Day	17% 25% 38% 14% 5%	500
	11th to 20th	Day	17% 26% 33% 15% 7% 1	492
	21st to end	Day	21% 23% 29% 18% 7% 2	500
May	1st to 10th	Day	19% 21% 28% 20% 9% 2	503
	11th to 20th	Day	19% 13% 25% 24% 16% 3	685
	21st to end	Day	23% 14% 22% 23% 14% 3	789
June	1st to 10th	Day	20% 18% 28% 24% 9% 1	730
	11th to 20th	Day	23% 20% 28% 21% 7% 1	730
	21st to end	Day	16% 14% 30% 26% 12% 3	730
July	1st to 10th	Day	13% 15% 28% 26% 15% 2	721
	11th to 20th	Day	14% 18% 29% 25% 11% 2	718
	21st to end	Day	8% 17% 35% 26% 11% 3	580
August	1st to 10th	Day	15% 16% 36% 21% 10% 2	487
	11th to 20th	Day	14% 19% 33% 25% 8% 1	477
	21st to end	Day	17% 21% 33% 19% 8% 1	539
September	1st to 10th	Day	19% 26% 29% 16% 8% 2	490
	11th to 20th	Day	22% 18% 34% 19% 5% 1	490
	21st to end	Day	25% 28% 28% 15% 3 1	490
October	1st to 10th	Day	21% 24% 28% 19% 6% 1	453
	11th to 20th	Day	21% 27% 28% 18% 6% 1	300
	21st to end	Day	20% 30% 30% 14% 5% 1	330
November	1st to 10th	Day	17% 32% 35% 9% 6% 1	300
	11th to 20th	Day	23% 28% 35% 11% 3 1	243
	21st to end	Day	20% 27% 27% 13% 11% 4	200
December	1st to 10th	Day	13% 34% 30% 16% 6% 2	200
	11th to 20th	Day	11% 32% 40% 16% 2 1	200
	21st to end	Day	13% 23% 41% 13% 8% 1	220
January	1st to 10th	Night	11% 30% 40% 15% 3	1000
	11th to 20th	Night	8% 30% 42% 16% 3 1	905
	21st to end	Night	8% 32% 39% 17% 4	880
February	1st to 10th	Night	10% 26% 35% 20% 8% 2	800
	11th to 20th	Night	8% 23% 40% 23% 6% 1	784
	21st to end	Night	10% 18% 39% 23% 9% 1	660
March	1st to 10th	Night	7% 23% 40% 22% 7% 1	800
	11th to 20th	Night	9% 23% 40% 21% 7% 1	800
	21st to end	Night	8% 18% 38% 24% 9% 2	880
April	1st to 10th	Night	9% 20% 34% 27% 9% 1	795
	11th to 20th	Night	9% 20% 36% 28% 7% 1	593
	21st to end	Night	12% 18% 34% 25% 10% 1	600
May	1st to 10th	Night	12% 13% 31% 30% 13% 1	462
	11th to 20th	Night	12% 10% 23% 32% 19% 3	394
	21st to end	Night	20% 11% 25% 26% 15% 2	433
June	1st to 10th	Night	18% 14% 27% 28% 11% 2	400
	11th to 20th	Night	21% 13% 30% 24% 12% 1	400
	21st to end	Night	13% 10% 27% 31% 19% 1	400
July	1st to 10th	Night	8% 7% 25% 40% 19% 1	390
	11th to 20th	Night	11% 11% 26% 34% 16% 2	388
	21st to end	Night	7% 8% 23% 41% 20% 1	416
August	1st to 10th	Night	9% 8% 17% 41% 23% 1	378
	11th to 20th	Night	10% 9% 20% 38% 20% 2	499
	21st to end	Night	14% 13% 25% 32% 15% 1	627
September	1st to 10th	Night	12% 13% 27% 30% 14% 4	731
	11th to 20th	Night	13% 15% 27% 26% 13% 6%	760
	21st to end	Night	18% 20% 30% 20% 9% 3	760
October	1st to 10th	Night	16% 16% 32% 26% 9% 2	760
	11th to 20th	Night	12% 22% 32% 27% 6% 1	760
	21st to end	Night	14% 22% 38% 20% 5% 1	836
November	1st to 10th	Night	12% 30% 39% 14% 5%	812
	11th to 20th	Night	14% 32% 39% 13% 3 1	1000
	21st to end	Night	11% 26% 41% 15% 5% 1	1000
December	1st to 10th	Night	10% 28% 37% 18% 6% 1	1000
	11th to 20th	Night	8% 30% 41% 17% 4	1000
	21st to end	Night	7% 27% 43% 16% 6% 1	1100

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