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 2026-07-31.

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	6% 6% 2 6% 4 4 4 3 5% 7% 52%	147439
	Night	7% 8% 3 7% 4 4 4 3 5% 7% 47%	142885
Transparency	Day	33% 6% 11% 24% 18% 8%	142179
	Night	37% 6% 13% 24% 14% 5%	139148
Seeing	Day	12% 15% 28% 26% 14% 4	16656
	Night	12% 12% 26% 31% 17% 2	25637

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	15% 16% 7% 14% 6% 6% 5% 4 5% 6% 16%	4722
	11th to 20th	Day	11% 10% 4 8% 5% 4 5% 3 6% 8% 37%	4740
	21st to end	Day	12% 12% 5% 12% 6% 5% 5% 4 5% 6% 28%	5305
February	1st to 10th	Day	11% 14% 4 11% 6% 4 5% 4 5% 6% 29%	1890
	11th to 20th	Day	12% 12% 4 7% 4 6% 6% 5% 6% 8% 32%	1860
	21st to end	Day	9% 9% 3 10% 7% 5% 5% 5% 5% 7% 35%	1730
March	1st to 10th	Day	7% 7% 3 9% 6% 5% 6% 6% 9% 10% 34%	4618
	11th to 20th	Day	7% 9% 3 8% 6% 5% 5% 4 5% 6% 42%	5037
	21st to end	Day	6% 9% 4 10% 7% 7% 7% 5% 7% 9% 29%	5935
April	1st to 10th	Day	6% 7% 3 7% 6% 5% 6% 5% 6% 10% 39%	2520
	11th to 20th	Day	6% 7% 3 7% 4 4 5% 5% 8% 7% 44%	2489
	21st to end	Day	4 5% 2 5% 4 4 4 5% 7% 9% 51%	2664
May	1st to 10th	Day	7% 4 1 4 3 3 4 3 5% 6% 60%	8195
	11th to 20th	Day	3 3 2 5% 3 4 4 3 5% 8% 61%	8160
	21st to end	Day	4 4 1 4 3 4 4 4 6% 8% 58%	8992
June	1st to 10th	Day	7% 5% 1 4 4 4 5% 3 7% 8% 53%	2940
	11th to 20th	Day	4 3 1 4 4 4 4 3 6% 7% 61%	2940
	21st to end	Day	2 2 1 4 3 2 3 3 4 6% 69%	2940
July	1st to 10th	Day	1 1 1 2 1 1 1 2 2 4 83%	6459
	11th to 20th	Day	1 1 1 1 1 1 2 2 2 3 85%	6460
	21st to end	Day	2 1 1 2 1 2 2 2 3 4 80%	7021
August	1st to 10th	Day	3 3 1 3 2 2 3 2 4 6% 72%	6168
	11th to 20th	Day	2 1 2 2 2 3 3 4 6% 74%	5756
	21st to end	Day	4 3 2 5% 3 3 3 3 4 6% 65%	5984
September	1st to 10th	Day	2 1 1 3 2 2 3 2 4 6% 75%	2400
	11th to 20th	Day	3 4 2 4 3 4 4 4 5% 6% 62%	2400
	21st to end	Day	6% 4 2 5% 3 4 3 3 4 6% 59%	2154
October	1st to 10th	Day	5% 3 1 4 3 3 3 3 5% 7% 63%	3280
	11th to 20th	Day	4 4 2 6% 4 5% 6% 5% 8% 9% 47%	3261
	21st to end	Day	8% 7% 2 9% 6% 5% 5% 5% 6% 7% 40%	3297
November	1st to 10th	Day	9% 12% 3 8% 7% 5% 5% 5% 7% 9% 29%	1854
	11th to 20th	Day	9% 14% 5% 11% 7% 8% 6% 5% 7% 6% 23%	1688
	21st to end	Day	10% 12% 4 11% 7% 6% 5% 5% 6% 6% 29%	1680
December	1st to 10th	Day	8% 11% 5% 17% 8% 6% 5% 3 5% 5% 29%	2700
	11th to 20th	Day	14% 18% 7% 15% 7% 6% 5% 4 5% 5% 14%	3108
	21st to end	Day	12% 17% 6% 13% 6% 6% 6% 4 6% 6% 18%	4092
January	1st to 10th	Night	15% 19% 7% 15% 6% 6% 5% 3 5% 5% 15%	8172
	11th to 20th	Night	11% 9% 3 7% 4 4 3 3 6% 7% 43%	8220
	21st to end	Night	10% 13% 5% 11% 6% 5% 4 3 4 5% 34%	8880
February	1st to 10th	Night	10% 13% 5% 10% 7% 5% 5% 4 6% 6% 30%	2730
	11th to 20th	Night	10% 10% 4 8% 5% 4 5% 4 6% 7% 37%	2646
	21st to end	Night	8% 12% 3 8% 5% 5% 5% 4 6% 9% 35%	2076
March	1st to 10th	Night	5% 6% 3 7% 5% 5% 6% 6% 8% 11% 38%	5496
	11th to 20th	Night	6% 6% 3 8% 5% 5% 5% 5% 6% 6% 45%	5167
	21st to end	Night	6% 6% 3 9% 7% 6% 8% 6% 8% 10% 31%	5281
April	1st to 10th	Night	7% 7% 2 7% 5% 5% 5% 4 7% 9% 42%	2100
	11th to 20th	Night	6% 6% 2 6% 5% 4 4 4 6% 7% 49%	2079
	21st to end	Night	6% 5% 3 5% 4 4 4 4 7% 8% 51%	1952
May	1st to 10th	Night	5% 3 2 5% 3 3 3 3 4 6% 63%	4723
	11th to 20th	Night	3 3 1 4 3 3 4 3 5% 7% 62%	4700
	21st to end	Night	5% 3 1 4 3 3 4 3 5% 9% 60%	5181
June	1st to 10th	Night	8% 4 2 6% 4 3 3 4 7% 8% 52%	1680
	11th to 20th	Night	5% 4 1 4 3 3 4 4 4 7% 63%	1680
	21st to end	Night	3 3 1 4 2 4 3 2 4 5% 68%	1680
July	1st to 10th	Night	1 1 2 2 2 2 2 3 4 81%	3720
	11th to 20th	Night	1 1 1 1 1 1 2 2 2 3 85%	3720
	21st to end	Night	1 1 1 2 1 1 1 1 3 6% 81%	4050
August	1st to 10th	Night	2 2 1 3 2 3 3 3 5% 7% 68%	3622
	11th to 20th	Night	2 2 1 2 3 3 3 2 4 5% 74%	4093
	21st to end	Night	3 3 1 5% 2 3 3 3 4 6% 67%	5015
September	1st to 10th	Night	1 2 1 3 2 2 2 2 4 6% 75%	2000
	11th to 20th	Night	3 3 1 4 3 4 4 3 5% 6% 65%	2000
	21st to end	Night	5% 4 1 4 3 3 4 3 5% 7% 63%	2243
October	1st to 10th	Night	3 3 1 4 3 3 3 3 5% 7% 65%	3920
	11th to 20th	Night	5% 4 2 5% 4 5% 5% 4 7% 9% 50%	3897
	21st to end	Night	7% 5% 2 5% 4 5% 6% 5% 7% 8% 43%	4505
November	1st to 10th	Night	12% 9% 2 7% 5% 5% 5% 4 7% 9% 35%	2665
	11th to 20th	Night	12% 13% 4 8% 6% 5% 6% 5% 5% 6% 29%	2930
	21st to end	Night	10% 11% 3 10% 6% 5% 5% 4 5% 7% 33%	2940
December	1st to 10th	Night	7% 9% 4 12% 5% 5% 6% 4 6% 6% 36%	4700
	11th to 20th	Night	18% 18% 6% 12% 7% 6% 5% 4 5% 6% 13%	5316
	21st to end	Night	17% 14% 6% 9% 5% 4 5% 3 5% 7% 25%	7106

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	68% 9% 10% 10% 3	4723
	11th to 20th	Day	44% 6% 15% 26% 8% 1	4740
	21st to end	Day	54% 6% 12% 20% 8%	5305
February	1st to 10th	Day	54% 9% 16% 16% 4	1890
	11th to 20th	Day	50% 9% 15% 19% 7%	1869
	21st to end	Day	48% 10% 15% 15% 12% 1	1730
March	1st to 10th	Day	41% 7% 11% 24% 16%	4618
	11th to 20th	Day	43% 6% 11% 30% 10%	5037
	21st to end	Day	48% 11% 14% 21% 6%	5935
April	1st to 10th	Day	40% 10% 15% 23% 11%	2520
	11th to 20th	Day	38% 7% 15% 22% 15% 2	2492
	21st to end	Day	30% 8% 14% 29% 16% 3	2664
May	1st to 10th	Day	26% 4 6% 29% 31% 4	8195
	11th to 20th	Day	23% 4 16% 32% 22% 3	8163
	21st to end	Day	25% 7% 17% 34% 16% 2	8994
June	1st to 10th	Day	30% 7% 12% 28% 18% 4	2940
	11th to 20th	Day	25% 5% 12% 35% 20% 4	2940
	21st to end	Day	18% 4 11% 34% 24% 9%	2940
July	1st to 10th	Day	9% 2 5% 18% 34% 32%	6391
	11th to 20th	Day	8% 2 4 12% 31% 44%	6385
	21st to end	Day	11% 1 7% 28% 34% 20%	6822
August	1st to 10th	Day	14% 2 6% 17% 34% 26%	4494
	11th to 20th	Day	14% 3 9% 36% 28% 11%	4167
	21st to end	Day	19% 3 10% 26% 32% 10%	4311
September	1st to 10th	Day	13% 4 9% 30% 29% 16%	2400
	11th to 20th	Day	23% 6% 10% 29% 24% 8%	2400
	21st to end	Day	27% 5% 12% 29% 20% 6%	2154
October	1st to 10th	Day	23% 5% 10% 34% 24% 4	3280
	11th to 20th	Day	32% 7% 18% 25% 17% 1	3261
	21st to end	Day	41% 6% 14% 27% 10% 1	3297
November	1st to 10th	Day	49% 8% 17% 20% 6% 1	1854
	11th to 20th	Day	58% 9% 15% 15% 2	1688
	21st to end	Day	52% 8% 19% 15% 6%	1680
December	1st to 10th	Day	52% 11% 13% 21% 4	2700
	11th to 20th	Day	69% 8% 11% 9% 2	3108
	21st to end	Day	63% 9% 14% 12% 2	4092
January	1st to 10th	Night	70% 8% 9% 10% 2	8172
	11th to 20th	Night	40% 6% 14% 31% 9% 1	8220
	21st to end	Night	52% 6% 12% 20% 10%	8880
February	1st to 10th	Night	52% 9% 19% 16% 4	2730
	11th to 20th	Night	45% 8% 17% 21% 8% 1	2648
	21st to end	Night	47% 9% 16% 18% 10% 1	2076
March	1st to 10th	Night	36% 7% 14% 27% 16%	5496
	11th to 20th	Night	38% 6% 16% 29% 11%	5167
	21st to end	Night	43% 13% 18% 22% 3	5281
April	1st to 10th	Night	37% 9% 18% 26% 9% 1	2100
	11th to 20th	Night	35% 7% 17% 26% 13% 3	2079
	21st to end	Night	30% 9% 15% 28% 14% 3	1952
May	1st to 10th	Night	24% 3 7% 31% 31% 3	4721
	11th to 20th	Night	22% 6% 17% 35% 19% 2	4700
	21st to end	Night	22% 7% 24% 31% 16% 1	5182
June	1st to 10th	Night	30% 8% 13% 31% 14% 4	1680
	11th to 20th	Night	23% 6% 13% 35% 20% 2	1680
	21st to end	Night	19% 4 10% 35% 23% 8%	1680
July	1st to 10th	Night	10% 2 6% 22% 32% 28%	3680
	11th to 20th	Night	8% 3 5% 12% 35% 38%	3672
	21st to end	Night	8% 1 6% 31% 33% 20%	3937
August	1st to 10th	Night	15% 2 6% 17% 34% 25%	2628
	11th to 20th	Night	13% 3 9% 40% 26% 10%	2957
	21st to end	Night	15% 3 11% 28% 30% 12%	3608
September	1st to 10th	Night	12% 3 11% 29% 28% 16%	2000
	11th to 20th	Night	20% 5% 11% 31% 21% 12%	2000
	21st to end	Night	22% 5% 12% 31% 23% 7%	2243
October	1st to 10th	Night	21% 4 11% 34% 28% 2	3920
	11th to 20th	Night	31% 6% 18% 26% 16% 2	3897
	21st to end	Night	35% 6% 14% 31% 12% 1	4505
November	1st to 10th	Night	46% 8% 14% 24% 8%	2665
	11th to 20th	Night	54% 9% 13% 19% 4	2930
	21st to end	Night	49% 8% 18% 19% 6%	2940
December	1st to 10th	Night	44% 10% 15% 27% 4	4700
	11th to 20th	Night	70% 7% 13% 8% 2	5316
	21st to end	Night	58% 8% 17% 14% 4	7106

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	25% 15% 23% 23% 10% 3	220
	11th to 20th	Day	24% 9% 24% 25% 16% 2	220
	21st to end	Day	18% 11% 23% 30% 16% 1	282
February	1st to 10th	Day	20% 17% 27% 26% 9% 1	430
	11th to 20th	Day	21% 18% 25% 24% 12% 1	433
	21st to end	Day	18% 19% 29% 24% 7% 2	446
March	1st to 10th	Day	17% 18% 28% 26% 9% 1	540
	11th to 20th	Day	17% 20% 26% 23% 12% 3	540
	21st to end	Day	17% 19% 32% 22% 9% 1	594
April	1st to 10th	Day	16% 20% 31% 19% 11% 3	540
	11th to 20th	Day	14% 24% 30% 20% 10% 2	532
	21st to end	Day	10% 24% 33% 21% 9% 3	540
May	1st to 10th	Day	13% 15% 31% 26% 12% 3	543
	11th to 20th	Day	17% 16% 29% 22% 14% 3	568
	21st to end	Day	11% 14% 30% 27% 13% 4	617
June	1st to 10th	Day	12% 21% 23% 26% 14% 4	570
	11th to 20th	Day	12% 21% 33% 21% 10% 2	570
	21st to end	Day	6% 14% 31% 29% 16% 4	570
July	1st to 10th	Day	3 9% 40% 31% 14% 2	566
	11th to 20th	Day	3 13% 38% 27% 16% 3	564
	21st to end	Day	2 10% 30% 32% 19% 6%	616
August	1st to 10th	Day	6% 9% 28% 27% 22% 9%	527
	11th to 20th	Day	2 7% 27% 32% 23% 9%	517
	21st to end	Day	6% 11% 28% 28% 21% 7%	583
September	1st to 10th	Day	3 9% 25% 34% 22% 7%	530
	11th to 20th	Day	7% 10% 30% 31% 18% 4	530
	21st to end	Day	9% 14% 24% 27% 21% 5%	530
October	1st to 10th	Day	11% 15% 26% 24% 19% 6%	530
	11th to 20th	Day	12% 16% 23% 26% 17% 6%	530
	21st to end	Day	14% 18% 26% 23% 15% 4	423
November	1st to 10th	Day	18% 17% 26% 25% 12% 2	330
	11th to 20th	Day	17% 15% 32% 21% 12% 3	223
	21st to end	Day	19% 11% 28% 29% 12% 2	220
December	1st to 10th	Day	20% 19% 15% 28% 12% 7%	220
	11th to 20th	Day	19% 14% 27% 31% 9%	220
	21st to end	Day	15% 21% 23% 29% 11% 1	242
January	1st to 10th	Night	24% 13% 22% 27% 12% 1	840
	11th to 20th	Night	21% 9% 18% 31% 18% 3	840
	21st to end	Night	19% 8% 17% 33% 20% 2	924
February	1st to 10th	Night	18% 15% 18% 34% 14% 2	840
	11th to 20th	Night	15% 14% 21% 34% 14% 1	824
	21st to end	Night	18% 13% 25% 34% 9% 1	692
March	1st to 10th	Night	12% 13% 25% 35% 14% 1	840
	11th to 20th	Night	11% 12% 26% 34% 16% 1	840
	21st to end	Night	12% 16% 29% 29% 12% 1	924
April	1st to 10th	Night	12% 16% 28% 28% 14% 1	840
	11th to 20th	Night	10% 19% 29% 27% 12% 2	831
	21st to end	Night	9% 18% 36% 23% 13% 1	692
May	1st to 10th	Night	8% 15% 30% 30% 15% 2	420
	11th to 20th	Night	11% 10% 31% 29% 16% 3	414
	21st to end	Night	8% 10% 33% 31% 15% 3	455
June	1st to 10th	Night	10% 16% 35% 23% 14% 1	420
	11th to 20th	Night	8% 20% 39% 25% 8%	420
	21st to end	Night	5% 14% 35% 28% 17% 1	420
July	1st to 10th	Night	2 11% 39% 32% 15% 1	410
	11th to 20th	Night	1 12% 44% 31% 11% 2	408
	21st to end	Night	1 9% 34% 34% 20% 1	458
August	1st to 10th	Night	3 7% 35% 33% 18% 3	412
	11th to 20th	Night	4 5% 25% 31% 26% 8%	609
	21st to end	Night	3 11% 29% 31% 23% 4	880
September	1st to 10th	Night	2 8% 28% 32% 27% 3	800
	11th to 20th	Night	4 7% 28% 30% 26% 5%	800
	21st to end	Night	7% 10% 20% 31% 28% 4	800
October	1st to 10th	Night	7% 8% 23% 37% 23% 2	800
	11th to 20th	Night	9% 11% 22% 31% 23% 3	800
	21st to end	Night	12% 10% 24% 34% 16% 3	880
November	1st to 10th	Night	17% 10% 20% 38% 14% 1	820
	11th to 20th	Night	20% 13% 21% 30% 13% 2	840
	21st to end	Night	14% 10% 21% 35% 17% 3	840
December	1st to 10th	Night	17% 10% 21% 29% 18% 3	840
	11th to 20th	Night	21% 9% 22% 35% 12% 1	840
	21st to end	Night	22% 11% 23% 32% 10% 1	924

Page generated at 2026-07-28 00:25:22. Version ac07

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