Kah-Nee-Ta Resort
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kah-Nee-Ta Resort clear sky chart from 2005-11-06 to 2024-11-05.

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% 7% 2 6% 4 4 4 4 5% 6% 49%	105392
	Night	9% 8% 3 7% 5% 4 4 4 5% 7% 44%	102343
Transparency	Day	33% 7% 12% 21% 17% 9%	105135
	Night	36% 9% 15% 21% 13% 6%	102189
Seeing	Day	11% 12% 23% 27% 20% 7%	14600
	Night	12% 6% 20% 39% 21% 2	23610

By Month

Percentage Cloud Cover SW (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	13% 15% 5% 13% 8% 7% 7% 5% 7% 7% 11%	2539
	11th to 20th	Day	21% 17% 5% 11% 6% 6% 5% 3 5% 6% 15%	2540
	21st to end	Day	14% 15% 4 10% 8% 7% 7% 4 6% 8% 17%	2952
February	1st to 10th	Day	13% 13% 4 7% 6% 6% 6% 6% 6% 7% 26%	1710
	11th to 20th	Day	10% 10% 4 8% 6% 6% 5% 5% 9% 6% 30%	1665
	21st to end	Day	8% 13% 4 11% 7% 5% 6% 4 8% 7% 28%	1570
March	1st to 10th	Day	7% 10% 3 9% 6% 5% 6% 6% 8% 9% 30%	3155
	11th to 20th	Day	7% 9% 3 6% 5% 4 4 3 5% 7% 46%	3490
	21st to end	Day	8% 12% 4 11% 7% 6% 6% 5% 7% 8% 25%	4005
April	1st to 10th	Day	10% 12% 3 8% 7% 5% 6% 5% 6% 7% 30%	2280
	11th to 20th	Day	10% 10% 3 7% 7% 5% 5% 4 6% 6% 38%	2249
	21st to end	Day	7% 7% 2 7% 5% 5% 5% 4 6% 8% 43%	2375
May	1st to 10th	Day	12% 7% 2 6% 5% 3 4 3 5% 6% 47%	4420
	11th to 20th	Day	4 3 1 4 3 3 3 2 5% 7% 63%	4377
	21st to end	Day	9% 6% 2 6% 4 5% 4 4 6% 8% 45%	4813
June	1st to 10th	Day	10% 6% 2 6% 5% 5% 4 4 6% 8% 44%	2660
	11th to 20th	Day	7% 4 2 5% 4 4 4 3 6% 7% 53%	2660
	21st to end	Day	3 3 1 3 2 3 3 3 4 6% 68%	2660
July	1st to 10th	Day	1 1 1 1 1 2 1 3 3 86%	4420
	11th to 20th	Day	2 1 1 2 1 1 2 2 2 4 83%	4420
	21st to end	Day	2 1 1 2 1 1 2 2 3 4 82%	4790
August	1st to 10th	Day	2 3 1 3 2 2 2 2 4 5% 75%	4257
	11th to 20th	Day	1 1 1 3 3 3 3 3 4 6% 71%	4009
	21st to end	Day	3 3 1 3 2 2 3 2 3 5% 72%	4180
September	1st to 10th	Day	2 2 1 2 1 2 3 2 4 5% 76%	2280
	11th to 20th	Day	4 3 2 5% 4 4 4 4 5% 6% 59%	2280
	21st to end	Day	8% 5% 2 5% 3 3 3 3 5% 7% 57%	2037
October	1st to 10th	Day	5% 4 2 4 3 3 4 3 5% 7% 60%	3180
	11th to 20th	Day	6% 5% 2 6% 5% 5% 5% 4 7% 10% 45%	3161
	21st to end	Day	11% 9% 3 8% 6% 6% 6% 4 6% 6% 34%	3264
November	1st to 10th	Day	13% 12% 4 8% 6% 6% 6% 3 7% 8% 27%	1710
	11th to 20th	Day	13% 13% 4 11% 7% 6% 6% 5% 7% 7% 21%	1522
	21st to end	Day	11% 12% 2 10% 7% 5% 5% 5% 6% 8% 29%	1520
December	1st to 10th	Day	11% 10% 5% 10% 8% 6% 6% 4 6% 5% 29%	1520
	11th to 20th	Day	12% 13% 6% 12% 8% 6% 6% 5% 9% 8% 14%	1928
	21st to end	Day	13% 17% 6% 12% 8% 7% 6% 5% 6% 6% 14%	2794
January	1st to 10th	Night	14% 16% 7% 15% 8% 6% 5% 4 5% 7% 12%	4406
	11th to 20th	Night	21% 17% 5% 10% 6% 5% 5% 4 6% 6% 15%	4420
	21st to end	Night	15% 14% 5% 12% 7% 6% 6% 5% 6% 7% 16%	4707
February	1st to 10th	Night	11% 13% 4 9% 6% 5% 5% 4 6% 8% 28%	2470
	11th to 20th	Night	10% 12% 3 8% 6% 5% 5% 4 6% 7% 35%	2402
	21st to end	Night	11% 14% 3 8% 7% 6% 6% 4 6% 7% 28%	1884
March	1st to 10th	Night	7% 10% 4 9% 6% 6% 6% 5% 6% 8% 33%	3717
	11th to 20th	Night	6% 8% 2 6% 4 4 5% 3 4 7% 50%	3490
	21st to end	Night	8% 10% 4 10% 7% 6% 7% 5% 8% 9% 25%	3648
April	1st to 10th	Night	10% 9% 3 9% 5% 4 4 4 7% 8% 37%	1900
	11th to 20th	Night	8% 9% 3 8% 5% 4 5% 4 6% 7% 41%	1879
	21st to end	Night	9% 8% 3 6% 4 5% 5% 4 6% 8% 44%	1801
May	1st to 10th	Night	13% 7% 2 6% 3 3 4 3 5% 6% 49%	2540
	11th to 20th	Night	4 3 1 3 3 3 3 3 4 6% 67%	2516
	21st to end	Night	8% 5% 2 4 3 4 4 4 5% 7% 54%	2762
June	1st to 10th	Night	11% 6% 2 6% 4 4 4 4 5% 7% 48%	1520
	11th to 20th	Night	6% 5% 2 5% 4 3 3 3 5% 7% 58%	1520
	21st to end	Night	4 4 1 3 2 3 2 3 4 5% 69%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 1 2 3 88%	2540
	11th to 20th	Night	1 1 1 2 2 1 2 2 2 4 82%	2540
	21st to end	Night	2 2 1 2 1 1 1 1 2 4 83%	2761
August	1st to 10th	Night	2 2 1 3 2 2 2 3 4 5% 74%	2674
	11th to 20th	Night	1 1 1 2 2 2 4 2 4 6% 74%	2830
	21st to end	Night	2 2 1 2 2 2 2 2 4 5% 76%	3498
September	1st to 10th	Night	2 1 1 2 1 1 2 2 3 5% 79%	1900
	11th to 20th	Night	5% 2 1 4 3 3 4 3 5% 6% 64%	1900
	21st to end	Night	6% 4 1 4 3 3 4 3 5% 7% 61%	2140
October	1st to 10th	Night	5% 4 2 4 2 2 3 3 3 5% 67%	3800
	11th to 20th	Night	7% 6% 2 6% 4 5% 5% 3 6% 8% 48%	3777
	21st to end	Night	9% 7% 2 8% 5% 6% 6% 5% 7% 8% 38%	4299
November	1st to 10th	Night	13% 10% 4 8% 6% 6% 5% 4 5% 8% 31%	2469
	11th to 20th	Night	13% 12% 4 9% 5% 6% 6% 4 7% 7% 27%	2655
	21st to end	Night	9% 9% 3 7% 6% 5% 6% 5% 6% 9% 34%	2660
December	1st to 10th	Night	13% 12% 4 10% 8% 6% 5% 4 5% 7% 26%	2660
	11th to 20th	Night	12% 15% 5% 13% 8% 6% 6% 4 7% 7% 15%	3276
	21st to end	Night	12% 13% 5% 16% 8% 7% 7% 6% 5% 5% 16%	4862

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	57% 15% 16% 10% 2	2539
	11th to 20th	Day	66% 8% 14% 8% 3 1	2540
	21st to end	Day	59% 14% 13% 11% 4	2952
February	1st to 10th	Day	53% 10% 16% 17% 4	1710
	11th to 20th	Day	46% 12% 15% 19% 6% 1	1674
	21st to end	Day	48% 12% 17% 16% 7%	1570
March	1st to 10th	Day	40% 10% 15% 25% 11%	3155
	11th to 20th	Day	35% 8% 16% 31% 11%	3490
	21st to end	Day	48% 14% 15% 17% 5%	4005
April	1st to 10th	Day	47% 10% 16% 18% 9% 1	2280
	11th to 20th	Day	43% 8% 16% 18% 12% 3	2252
	21st to end	Day	35% 9% 16% 26% 12% 2	2375
May	1st to 10th	Day	32% 10% 13% 25% 20% 1	4420
	11th to 20th	Day	21% 5% 11% 31% 28% 4	4380
	21st to end	Day	33% 10% 20% 26% 10% 1	4814
June	1st to 10th	Day	36% 7% 13% 26% 15% 3	2660
	11th to 20th	Day	29% 6% 14% 32% 15% 3	2660
	21st to end	Day	17% 4 13% 32% 24% 10%	2660
July	1st to 10th	Day	7% 2 5% 13% 24% 49%	4351
	11th to 20th	Day	8% 1 6% 9% 22% 54%	4345
	21st to end	Day	9% 2 6% 18% 35% 31%	4639
August	1st to 10th	Day	14% 3 6% 16% 37% 26%	4241
	11th to 20th	Day	15% 3 9% 33% 29% 11%	4048
	21st to end	Day	17% 3 8% 28% 30% 14%	4179
September	1st to 10th	Day	12% 3 8% 27% 32% 18%	2280
	11th to 20th	Day	24% 6% 12% 26% 22% 10%	2280
	21st to end	Day	27% 6% 13% 25% 22% 7%	2037
October	1st to 10th	Day	24% 6% 9% 25% 28% 8%	3180
	11th to 20th	Day	33% 8% 18% 24% 16% 1	3161
	21st to end	Day	45% 7% 12% 23% 11% 2	3264
November	1st to 10th	Day	52% 9% 14% 18% 7% 1	1710
	11th to 20th	Day	57% 11% 15% 14% 4	1522
	21st to end	Day	50% 9% 17% 16% 7%	1520
December	1st to 10th	Day	53% 10% 12% 18% 7%	1520
	11th to 20th	Day	58% 12% 17% 11% 2	1928
	21st to end	Day	62% 10% 16% 11% 2	2794
January	1st to 10th	Night	63% 13% 13% 9% 2	4406
	11th to 20th	Night	62% 13% 13% 7% 4 1	4420
	21st to end	Night	60% 15% 11% 11% 3	4707
February	1st to 10th	Night	51% 10% 19% 16% 5%	2470
	11th to 20th	Night	44% 11% 19% 20% 6% 1	2404
	21st to end	Night	49% 11% 15% 17% 7% 1	1884
March	1st to 10th	Night	39% 11% 16% 25% 8% 1	3717
	11th to 20th	Night	29% 7% 21% 34% 8%	3490
	21st to end	Night	44% 16% 22% 14% 4	3648
April	1st to 10th	Night	42% 9% 21% 20% 7% 1	1900
	11th to 20th	Night	39% 9% 18% 20% 11% 3	1879
	21st to end	Night	36% 11% 17% 23% 10% 3	1801
May	1st to 10th	Night	31% 10% 13% 29% 16%	2540
	11th to 20th	Night	18% 6% 13% 40% 21% 2	2516
	21st to end	Night	25% 12% 33% 23% 7%	2762
June	1st to 10th	Night	35% 10% 13% 28% 12% 1	1520
	11th to 20th	Night	25% 7% 17% 36% 12% 3	1520
	21st to end	Night	18% 4 12% 33% 24% 8%	1520
July	1st to 10th	Night	6% 2 7% 15% 27% 44%	2500
	11th to 20th	Night	9% 2 6% 15% 19% 49%	2492
	21st to end	Night	8% 2 5% 21% 37% 28%	2674
August	1st to 10th	Night	13% 2 6% 17% 37% 24%	2666
	11th to 20th	Night	12% 3 11% 39% 27% 8%	2857
	21st to end	Night	12% 3 13% 30% 30% 12%	3498
September	1st to 10th	Night	9% 3 10% 29% 32% 16%	1900
	11th to 20th	Night	20% 7% 13% 28% 22% 11%	1900
	21st to end	Night	22% 5% 12% 28% 24% 8%	2140
October	1st to 10th	Night	20% 4 11% 30% 30% 3	3800
	11th to 20th	Night	30% 8% 20% 24% 15% 1	3777
	21st to end	Night	40% 8% 14% 27% 11% 1	4299
November	1st to 10th	Night	47% 10% 13% 20% 8% 1	2469
	11th to 20th	Night	52% 10% 16% 18% 4	2655
	21st to end	Night	43% 10% 18% 21% 7% 1	2660
December	1st to 10th	Night	55% 10% 15% 15% 4	2660
	11th to 20th	Night	60% 11% 15% 12% 2	3276
	21st to end	Night	57% 16% 13% 10% 4	4862

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	26% 13% 23% 21% 13% 4	180
	11th to 20th	Day	23% 10% 21% 28% 14% 3	180
	21st to end	Day	18% 9% 20% 31% 19% 3	291
February	1st to 10th	Day	21% 14% 19% 28% 14% 4	370
	11th to 20th	Day	17% 16% 25% 24% 14% 2	365
	21st to end	Day	16% 16% 27% 26% 13% 2	382
March	1st to 10th	Day	18% 15% 25% 29% 11% 2	460
	11th to 20th	Day	15% 17% 21% 29% 14% 4	460
	21st to end	Day	17% 16% 27% 27% 12% 1	506
April	1st to 10th	Day	21% 18% 22% 23% 12% 5%	460
	11th to 20th	Day	16% 16% 30% 21% 12% 6%	452
	21st to end	Day	10% 22% 25% 24% 16% 4	460
May	1st to 10th	Day	12% 16% 24% 26% 15% 6%	463
	11th to 20th	Day	13% 13% 24% 26% 16% 8%	488
	21st to end	Day	13% 11% 20% 28% 21% 7%	529
June	1st to 10th	Day	10% 15% 23% 23% 19% 9%	490
	11th to 20th	Day	9% 18% 26% 28% 14% 4	490
	21st to end	Day	4 10% 21% 31% 25% 8%	490
July	1st to 10th	Day	2 8% 25% 33% 26% 6%	486
	11th to 20th	Day	1 9% 24% 28% 29% 10%	484
	21st to end	Day	2 5% 24% 30% 26% 15%	531
August	1st to 10th	Day	3 6% 19% 32% 24% 17%	487
	11th to 20th	Day	1 6% 18% 28% 27% 20%	477
	21st to end	Day	5% 7% 22% 27% 27% 13%	539
September	1st to 10th	Day	3 5% 21% 29% 28% 15%	490
	11th to 20th	Day	6% 7% 21% 26% 31% 9%	490
	21st to end	Day	10% 9% 19% 29% 25% 8%	490
October	1st to 10th	Day	10% 10% 22% 27% 23% 9%	490
	11th to 20th	Day	13% 10% 18% 26% 25% 8%	490
	21st to end	Day	16% 14% 23% 23% 18% 6%	430
November	1st to 10th	Day	17% 12% 24% 30% 14% 2	282
	11th to 20th	Day	13% 11% 24% 23% 24% 6%	180
	21st to end	Day	16% 11% 21% 31% 18% 3	180
December	1st to 10th	Day	10% 13% 23% 27% 19% 8%	180
	11th to 20th	Day	21% 9% 28% 31% 10% 1	180
	21st to end	Day	18% 15% 24% 26% 16% 2	198
January	1st to 10th	Night	19% 8% 25% 33% 13% 3	760
	11th to 20th	Night	18% 8% 21% 31% 20% 2	760
	21st to end	Night	17% 6% 17% 38% 19% 2	836
February	1st to 10th	Night	17% 7% 25% 34% 16% 1	760
	11th to 20th	Night	14% 7% 27% 35% 17% 1	744
	21st to end	Night	20% 9% 24% 35% 12%	628
March	1st to 10th	Night	15% 9% 25% 36% 14% 1	760
	11th to 20th	Night	11% 9% 19% 42% 18% 1	760
	21st to end	Night	10% 9% 29% 35% 17%	836
April	1st to 10th	Night	15% 8% 24% 32% 19% 1	760
	11th to 20th	Night	12% 8% 26% 35% 16% 3	751
	21st to end	Night	12% 7% 23% 36% 20% 1	661
May	1st to 10th	Night	8% 6% 23% 41% 20% 2	380
	11th to 20th	Night	7% 5% 17% 45% 25% 1	374
	21st to end	Night	5% 6% 18% 44% 27% 1	411
June	1st to 10th	Night	13% 4 15% 46% 21% 1	380
	11th to 20th	Night	7% 5% 24% 46% 17% 1	380
	21st to end	Night	8% 1 18% 46% 27% 1	380
July	1st to 10th	Night	2 1 13% 56% 27% 1	370
	11th to 20th	Night	1 15% 60% 22% 2	368
	21st to end	Night	1 1 11% 50% 34% 2	416
August	1st to 10th	Night	2 1 10% 45% 37% 5%	458
	11th to 20th	Night	2 1 7% 36% 46% 9%	569
	21st to end	Night	3 2 18% 43% 31% 4	836
September	1st to 10th	Night	2 2 15% 43% 34% 4	760
	11th to 20th	Night	5% 2 13% 41% 34% 6%	760
	21st to end	Night	7% 5% 13% 40% 31% 5%	760
October	1st to 10th	Night	9% 3 16% 42% 26% 4	760
	11th to 20th	Night	10% 4 19% 38% 26% 4	760
	21st to end	Night	14% 5% 22% 37% 17% 4	836
November	1st to 10th	Night	14% 7% 22% 41% 16% 1	760
	11th to 20th	Night	17% 11% 21% 35% 16% 1	760
	21st to end	Night	14% 7% 20% 39% 18% 2	760
December	1st to 10th	Night	17% 7% 19% 37% 18% 2	760
	11th to 20th	Night	17% 7% 22% 37% 16% 1	760
	21st to end	Night	18% 9% 28% 34% 11% 1	836

Page generated at 2024-11-02 23:11:08. Version ac07

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