Klondike
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Klondike clear sky chart from 2005-11-06 to 2025-03-27.

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% 3 6% 4 4 4 3 5% 6% 51%	112984
	Night	8% 8% 3 7% 4 4 4 3 5% 6% 46%	115093
Transparency	Day	34% 6% 12% 23% 17% 8%	112727
	Night	38% 7% 14% 23% 13% 5%	114939
Seeing	Day	12% 16% 28% 26% 14% 4	14891
	Night	12% 12% 25% 31% 17% 2	24084

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	18% 18% 8% 14% 6% 6% 4 3 4 5% 14%	3639
	11th to 20th	Day	14% 13% 5% 7% 4 4 4 3 5% 7% 35%	3640
	21st to end	Day	14% 13% 5% 10% 5% 5% 5% 4 5% 5% 29%	4094
February	1st to 10th	Day	11% 14% 4 11% 6% 4 5% 4 5% 6% 29%	1800
	11th to 20th	Day	12% 12% 4 7% 4 6% 5% 5% 6% 8% 32%	1769
	21st to end	Day	8% 9% 3 10% 7% 5% 6% 5% 5% 7% 34%	1650
March	1st to 10th	Day	7% 8% 3 9% 6% 5% 6% 6% 9% 10% 33%	3238
	11th to 20th	Day	5% 7% 2 6% 5% 5% 4 4 5% 7% 50%	3553
	21st to end	Day	6% 9% 4 9% 6% 6% 6% 6% 8% 8% 32%	4125
April	1st to 10th	Day	6% 7% 3 7% 6% 5% 5% 5% 6% 10% 39%	2280
	11th to 20th	Day	6% 8% 3 7% 5% 5% 5% 5% 8% 7% 42%	2249
	21st to end	Day	4 5% 2 5% 4 4 5% 5% 8% 9% 49%	2410
May	1st to 10th	Day	9% 5% 1 4 3 3 4 3 5% 6% 56%	4420
	11th to 20th	Day	4 3 1 3 2 3 3 2 4 7% 66%	4377
	21st to end	Day	6% 6% 1 5% 4 5% 5% 4 6% 8% 51%	4813
June	1st to 10th	Day	7% 5% 2 5% 4 4 5% 4 7% 8% 50%	2660
	11th to 20th	Day	4 3 1 4 4 5% 4 3 6% 7% 59%	2660
	21st to end	Day	2 2 1 3 3 2 3 3 4 6% 70%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 2 4 85%	4420
	11th to 20th	Day	1 1 1 1 1 1 2 2 2 3 84%	4420
	21st to end	Day	1 1 1 1 1 2 2 2 3 4 82%	4790
August	1st to 10th	Day	3 2 1 3 2 2 3 2 3 5% 75%	4371
	11th to 20th	Day	2 2 1 3 2 2 3 2 4 6% 74%	3999
	21st to end	Day	3 2 1 4 3 3 3 2 4 5% 70%	4180
September	1st to 10th	Day	2 1 1 3 2 2 2 2 3 6% 77%	2280
	11th to 20th	Day	3 3 2 4 3 4 4 4 5% 7% 61%	2280
	21st to end	Day	6% 4 2 5% 3 4 3 4 4 6% 58%	2047
October	1st to 10th	Day	5% 3 1 3 3 3 3 3 5% 7% 63%	3180
	11th to 20th	Day	4 4 2 6% 4 5% 6% 5% 8% 9% 47%	3161
	21st to end	Day	8% 7% 2 9% 6% 6% 5% 5% 6% 7% 40%	3195
November	1st to 10th	Day	9% 12% 3 8% 6% 6% 5% 5% 8% 9% 30%	1764
	11th to 20th	Day	10% 14% 5% 11% 7% 8% 6% 5% 7% 6% 23%	1608
	21st to end	Day	10% 12% 4 11% 7% 6% 5% 5% 6% 6% 29%	1600
December	1st to 10th	Day	7% 11% 5% 17% 7% 6% 5% 3 5% 5% 29%	2620
	11th to 20th	Day	14% 18% 7% 15% 7% 6% 5% 4 5% 5% 14%	3028
	21st to end	Day	12% 17% 6% 13% 6% 6% 6% 4 6% 6% 18%	4004
January	1st to 10th	Night	17% 20% 7% 17% 6% 5% 4 3 4 4 13%	6306
	11th to 20th	Night	14% 11% 4 7% 3 3 3 3 5% 7% 38%	6320
	21st to end	Night	13% 15% 5% 10% 5% 4 4 3 4 4 35%	6864
February	1st to 10th	Night	10% 12% 5% 10% 6% 5% 5% 4 6% 6% 31%	2600
	11th to 20th	Night	9% 10% 4 8% 5% 4 5% 4 6% 7% 37%	2517
	21st to end	Night	8% 13% 3 8% 5% 5% 5% 4 6% 8% 35%	1980
March	1st to 10th	Night	5% 7% 3 7% 5% 6% 6% 6% 8% 11% 36%	3856
	11th to 20th	Night	6% 5% 2 6% 4 4 4 4 5% 6% 55%	3643
	21st to end	Night	6% 6% 3 8% 6% 6% 7% 5% 8% 11% 34%	3665
April	1st to 10th	Night	7% 7% 2 7% 5% 5% 5% 4 7% 9% 41%	1900
	11th to 20th	Night	6% 6% 2 6% 6% 4 4 4 6% 7% 48%	1879
	21st to end	Night	6% 5% 3 6% 4 5% 4 4 8% 8% 49%	1767
May	1st to 10th	Night	8% 6% 2 5% 3 3 3 3 5% 5% 57%	2540
	11th to 20th	Night	4 2 1 3 2 2 3 3 5% 6% 68%	2516
	21st to end	Night	4 4 1 5% 3 3 4 4 6% 8% 57%	2762
June	1st to 10th	Night	8% 4 2 6% 4 3 4 4 8% 8% 50%	1520
	11th to 20th	Night	5% 4 2 4 3 2 4 3 4 7% 62%	1520
	21st to end	Night	3 3 1 4 3 4 3 2 5% 4 69%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 2 3 87%	2540
	11th to 20th	Night	1 1 1 1 1 2 2 2 2 3 83%	2540
	21st to end	Night	1 1 1 1 1 1 1 3 4 85%	2761
August	1st to 10th	Night	2 3 1 3 2 2 3 2 4 6% 71%	2555
	11th to 20th	Night	2 2 1 2 2 2 3 3 4 5% 75%	2839
	21st to end	Night	2 2 1 4 2 2 3 2 4 5% 74%	3498
September	1st to 10th	Night	1 1 1 3 2 1 2 2 4 6% 77%	1900
	11th to 20th	Night	3 3 1 4 3 4 4 3 5% 6% 64%	1900
	21st to end	Night	5% 4 1 4 3 3 4 3 5% 7% 62%	2130
October	1st to 10th	Night	3 3 1 4 3 3 3 3 5% 7% 65%	3800
	11th to 20th	Night	5% 4 2 5% 4 5% 5% 4 7% 9% 49%	3777
	21st to end	Night	7% 6% 2 6% 4 5% 6% 5% 7% 8% 43%	4365
November	1st to 10th	Night	12% 9% 2 7% 5% 5% 5% 4 7% 8% 36%	2535
	11th to 20th	Night	13% 13% 4 8% 6% 5% 6% 5% 6% 6% 29%	2790
	21st to end	Night	9% 11% 3 10% 6% 5% 6% 4 5% 7% 33%	2800
December	1st to 10th	Night	7% 9% 4 12% 5% 5% 6% 4 6% 6% 36%	4560
	11th to 20th	Night	18% 18% 6% 13% 7% 6% 5% 4 5% 6% 13%	5176
	21st to end	Night	17% 14% 6% 9% 5% 4 5% 3 5% 7% 25%	6952

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	72% 9% 9% 8% 3	3639
	11th to 20th	Day	48% 7% 18% 22% 6%	3640
	21st to end	Day	53% 6% 11% 20% 9%	4094
February	1st to 10th	Day	54% 9% 16% 16% 4	1800
	11th to 20th	Day	50% 9% 15% 19% 7%	1778
	21st to end	Day	48% 10% 16% 15% 11%	1650
March	1st to 10th	Day	40% 8% 11% 26% 14%	3238
	11th to 20th	Day	35% 7% 13% 35% 10%	3553
	21st to end	Day	46% 12% 13% 21% 7%	4125
April	1st to 10th	Day	41% 10% 15% 22% 12%	2280
	11th to 20th	Day	40% 7% 15% 21% 14% 2	2252
	21st to end	Day	32% 9% 14% 28% 16% 2	2410
May	1st to 10th	Day	30% 7% 9% 29% 24% 1	4420
	11th to 20th	Day	21% 4 9% 32% 30% 5%	4380
	21st to end	Day	31% 11% 19% 28% 10% 1	4814
June	1st to 10th	Day	32% 8% 12% 28% 17% 3	2660
	11th to 20th	Day	26% 5% 12% 36% 18% 3	2660
	21st to end	Day	17% 4 10% 34% 25% 10%	2660
July	1st to 10th	Day	7% 2 5% 15% 26% 45%	4351
	11th to 20th	Day	8% 2 4 10% 23% 51%	4345
	21st to end	Day	9% 2 6% 17% 37% 28%	4639
August	1st to 10th	Day	14% 2 6% 16% 35% 27%	4355
	11th to 20th	Day	14% 3 9% 36% 28% 10%	4038
	21st to end	Day	19% 3 10% 26% 32% 10%	4179
September	1st to 10th	Day	12% 3 8% 31% 30% 16%	2280
	11th to 20th	Day	23% 6% 11% 28% 24% 8%	2280
	21st to end	Day	28% 5% 13% 29% 20% 5%	2047
October	1st to 10th	Day	23% 5% 10% 34% 25% 4	3180
	11th to 20th	Day	32% 7% 18% 25% 17% 1	3161
	21st to end	Day	42% 6% 14% 27% 10% 1	3195
November	1st to 10th	Day	48% 8% 17% 20% 6% 1	1764
	11th to 20th	Day	58% 9% 15% 15% 3	1608
	21st to end	Day	52% 8% 18% 15% 7% 1	1600
December	1st to 10th	Day	51% 11% 12% 21% 4	2620
	11th to 20th	Day	70% 8% 11% 9% 1	3028
	21st to end	Day	63% 9% 14% 12% 2	4004
January	1st to 10th	Night	74% 9% 8% 7% 2	6306
	11th to 20th	Night	46% 6% 18% 25% 5%	6320
	21st to end	Night	52% 7% 11% 20% 10%	6864
February	1st to 10th	Night	52% 9% 19% 16% 4	2600
	11th to 20th	Night	45% 8% 17% 21% 8% 1	2519
	21st to end	Night	47% 9% 16% 17% 9% 1	1980
March	1st to 10th	Night	38% 7% 12% 29% 13% 1	3856
	11th to 20th	Night	29% 7% 17% 35% 13%	3643
	21st to end	Night	40% 15% 18% 23% 4	3665
April	1st to 10th	Night	39% 9% 18% 24% 9% 1	1900
	11th to 20th	Night	36% 7% 16% 25% 12% 3	1879
	21st to end	Night	32% 10% 16% 27% 12% 3	1767
May	1st to 10th	Night	30% 5% 11% 30% 23% 1	2540
	11th to 20th	Night	18% 7% 11% 38% 24% 3	2516
	21st to end	Night	23% 11% 31% 27% 7% 1	2762
June	1st to 10th	Night	32% 9% 13% 31% 12% 4	1520
	11th to 20th	Night	23% 6% 14% 37% 18% 1	1520
	21st to end	Night	19% 5% 9% 36% 23% 8%	1520
July	1st to 10th	Night	7% 1 6% 15% 34% 37%	2500
	11th to 20th	Night	9% 3 6% 13% 24% 46%	2492
	21st to end	Night	7% 1 6% 19% 37% 30%	2674
August	1st to 10th	Night	15% 2 6% 16% 35% 26%	2547
	11th to 20th	Night	13% 3 9% 40% 27% 9%	2866
	21st to end	Night	15% 3 11% 29% 30% 12%	3498
September	1st to 10th	Night	11% 3 11% 30% 29% 17%	1900
	11th to 20th	Night	21% 5% 11% 30% 20% 13%	1900
	21st to end	Night	22% 5% 13% 30% 23% 7%	2130
October	1st to 10th	Night	21% 4 10% 34% 29% 2	3800
	11th to 20th	Night	30% 7% 19% 26% 16% 2	3777
	21st to end	Night	36% 6% 14% 31% 12% 1	4365
November	1st to 10th	Night	45% 7% 14% 24% 9%	2535
	11th to 20th	Night	54% 9% 13% 20% 4	2790
	21st to end	Night	49% 8% 18% 19% 6%	2800
December	1st to 10th	Night	44% 10% 15% 27% 4	4560
	11th to 20th	Night	70% 7% 13% 8% 2	5176
	21st to end	Night	58% 8% 16% 14% 4	6952

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% 16% 22% 23% 10% 4	200
	11th to 20th	Day	27% 10% 23% 24% 15% 2	200
	21st to end	Day	18% 12% 24% 28% 17% 2	258
February	1st to 10th	Day	22% 17% 26% 26% 9% 1	400
	11th to 20th	Day	22% 19% 24% 23% 11% 1	402
	21st to end	Day	17% 19% 28% 26% 7% 2	414
March	1st to 10th	Day	17% 16% 29% 26% 10% 1	500
	11th to 20th	Day	15% 20% 25% 24% 13% 3	500
	21st to end	Day	18% 19% 32% 22% 9% 1	531
April	1st to 10th	Day	19% 22% 31% 17% 9% 3	460
	11th to 20th	Day	14% 24% 32% 18% 9% 3	452
	21st to end	Day	11% 26% 32% 20% 9% 2	460
May	1st to 10th	Day	14% 17% 31% 25% 11% 3	463
	11th to 20th	Day	16% 15% 27% 23% 15% 4	488
	21st to end	Day	12% 15% 30% 27% 12% 3	529
June	1st to 10th	Day	12% 21% 24% 26% 14% 4	490
	11th to 20th	Day	13% 23% 31% 21% 9% 2	490
	21st to end	Day	6% 14% 31% 29% 15% 4	490
July	1st to 10th	Day	2 10% 41% 29% 15% 2	486
	11th to 20th	Day	4 12% 37% 29% 16% 2	484
	21st to end	Day	2 9% 30% 32% 19% 7%	531
August	1st to 10th	Day	5% 9% 29% 26% 22% 9%	487
	11th to 20th	Day	3 6% 25% 32% 24% 9%	477
	21st to end	Day	6% 11% 29% 27% 21% 7%	539
September	1st to 10th	Day	4 10% 26% 33% 21% 8%	490
	11th to 20th	Day	7% 11% 31% 29% 18% 4	490
	21st to end	Day	9% 15% 24% 27% 20% 4	490
October	1st to 10th	Day	11% 15% 26% 23% 20% 6%	490
	11th to 20th	Day	10% 16% 24% 27% 17% 7%	490
	21st to end	Day	15% 18% 27% 21% 14% 4	387
November	1st to 10th	Day	19% 17% 26% 25% 12% 1	300
	11th to 20th	Day	18% 16% 32% 19% 12% 3	203
	21st to end	Day	19% 10% 30% 27% 13% 2	200
December	1st to 10th	Day	19% 17% 15% 29% 13% 8%	200
	11th to 20th	Day	19% 14% 28% 31% 9% 1	200
	21st to end	Day	15% 21% 24% 29% 10%	220
January	1st to 10th	Night	25% 13% 22% 28% 12% 1	800
	11th to 20th	Night	22% 10% 19% 30% 17% 3	800
	21st to end	Night	20% 8% 18% 32% 20% 2	880
February	1st to 10th	Night	18% 15% 19% 33% 14% 2	800
	11th to 20th	Night	16% 15% 21% 33% 14% 1	784
	21st to end	Night	18% 14% 23% 35% 9% 1	660
March	1st to 10th	Night	12% 12% 25% 36% 14% 1	800
	11th to 20th	Night	11% 12% 25% 35% 16% 1	800
	21st to end	Night	12% 16% 29% 29% 12% 1	862
April	1st to 10th	Night	13% 17% 28% 28% 13% 2	760
	11th to 20th	Night	11% 20% 28% 25% 13% 2	751
	21st to end	Night	9% 18% 36% 24% 12% 1	627
May	1st to 10th	Night	9% 16% 30% 28% 15% 2	380
	11th to 20th	Night	10% 10% 30% 30% 18% 3	374
	21st to end	Night	8% 11% 33% 30% 15% 3	411
June	1st to 10th	Night	11% 16% 35% 23% 14% 1	380
	11th to 20th	Night	9% 20% 37% 25% 8% 1	380
	21st to end	Night	5% 15% 34% 29% 17% 1	380
July	1st to 10th	Night	2 11% 38% 32% 16% 1	370
	11th to 20th	Night	1 10% 44% 32% 11% 2	368
	21st to end	Night	1 9% 34% 34% 21% 1	416
August	1st to 10th	Night	3 7% 34% 34% 19% 4	391
	11th to 20th	Night	4 5% 24% 31% 27% 8%	578
	21st to end	Night	3 11% 30% 29% 23% 4	836
September	1st to 10th	Night	2 8% 27% 32% 28% 3	760
	11th to 20th	Night	4 7% 27% 29% 27% 5%	760
	21st to end	Night	7% 10% 20% 32% 27% 4	760
October	1st to 10th	Night	8% 8% 21% 38% 23% 2	760
	11th to 20th	Night	8% 11% 21% 32% 24% 3	760
	21st to end	Night	13% 10% 24% 33% 17% 3	836
November	1st to 10th	Night	17% 10% 20% 38% 15% 1	780
	11th to 20th	Night	21% 14% 21% 29% 13% 2	800
	21st to end	Night	13% 10% 21% 34% 18% 3	800
December	1st to 10th	Night	17% 10% 22% 30% 19% 3	800
	11th to 20th	Night	21% 9% 21% 35% 12% 2	800
	21st to end	Night	22% 12% 23% 32% 10% 1	880

Page generated at 2025-03-24 06:04:33. Version ac07

Copyright © 2025 Attilla Danko.