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 2024-02-15.

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	8% 7% 3 6% 5% 3 5% 5% 5% 7% 47%	78246
	Night	9% 9% 4 7% 5% 3 5% 4 5% 7% 42%	80852
Transparency	Day	37% 7% 12% 22% 16% 6%	77949
	Night	42% 8% 14% 21% 12% 4	80670
Seeing	Day	12% 16% 28% 26% 14% 4	13472
	Night	12% 12% 25% 31% 17% 2	22680

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	16% 19% 7% 10% 6% 4 5% 5% 5% 6% 17%	2539
	11th to 20th	Day	20% 18% 7% 8% 6% 3 5% 4 5% 8% 17%	2540
	21st to end	Day	20% 17% 7% 11% 8% 4 5% 5% 5% 5% 13%	2856
February	1st to 10th	Day	12% 13% 5% 10% 7% 3 6% 5% 5% 7% 30%	1710
	11th to 20th	Day	12% 10% 3 6% 5% 4 6% 6% 5% 8% 33%	1625
	21st to end	Day	8% 8% 4 9% 8% 4 6% 6% 5% 7% 34%	1480
March	1st to 10th	Day	10% 9% 3 8% 7% 4 6% 7% 8% 9% 29%	1800
	11th to 20th	Day	7% 9% 4 8% 8% 5% 7% 6% 6% 9% 30%	1948
	21st to end	Day	8% 9% 4 8% 7% 5% 7% 7% 7% 9% 30%	2305
April	1st to 10th	Day	7% 7% 4 6% 7% 4 6% 6% 6% 10% 38%	2160
	11th to 20th	Day	6% 7% 3 7% 5% 3 6% 6% 8% 7% 42%	2129
	21st to end	Day	5% 5% 2 4 4 3 5% 5% 7% 10% 50%	2282
May	1st to 10th	Day	4 4 2 4 4 3 5% 4 6% 8% 55%	2520
	11th to 20th	Day	7% 5% 3 5% 5% 4 5% 5% 6% 10% 44%	2477
	21st to end	Day	8% 6% 2 4 4 3 5% 5% 5% 8% 51%	2723
June	1st to 10th	Day	8% 4 2 4 4 3 5% 4 6% 8% 51%	2520
	11th to 20th	Day	5% 2 1 3 5% 3 5% 4 6% 7% 59%	2520
	21st to end	Day	3 2 1 3 3 2 3 4 4 6% 70%	2520
July	1st to 10th	Day	1 1 1 2 2 1 2 3 3 5% 78%	2520
	11th to 20th	Day	2 1 1 2 2 1 3 3 3 5% 78%	2520
	21st to end	Day	1 1 1 1 1 2 2 3 3 85%	2741
August	1st to 10th	Day	2 2 1 2 2 1 2 3 3 5% 77%	2491
	11th to 20th	Day	2 1 2 2 1 2 3 3 5% 79%	2284
	21st to end	Day	2 2 1 2 2 2 2 4 4 5% 74%	2376
September	1st to 10th	Day	2 1 1 3 2 1 2 2 3 6% 77%	2160
	11th to 20th	Day	3 3 2 3 4 3 4 4 5% 7% 62%	2160
	21st to end	Day	6% 5% 2 4 4 3 4 5% 4 6% 57%	1940
October	1st to 10th	Day	8% 4 3 4 4 3 5% 3 5% 7% 54%	1800
	11th to 20th	Day	6% 5% 2 5% 6% 3 5% 5% 7% 9% 47%	1800
	21st to end	Day	10% 7% 2 7% 6% 4 5% 6% 5% 6% 41%	1836
November	1st to 10th	Day	10% 10% 4 8% 6% 4 5% 6% 7% 9% 30%	1674
	11th to 20th	Day	9% 13% 5% 9% 8% 5% 8% 6% 6% 6% 23%	1528
	21st to end	Day	11% 11% 4 10% 7% 4 6% 6% 6% 6% 29%	1520
December	1st to 10th	Day	10% 15% 7% 8% 6% 3 6% 5% 5% 6% 29%	1520
	11th to 20th	Day	12% 17% 9% 14% 9% 4 6% 5% 5% 5% 15%	1928
	21st to end	Day	13% 18% 7% 12% 9% 5% 6% 4 4 5% 16%	2794
January	1st to 10th	Night	14% 18% 6% 11% 8% 5% 6% 5% 5% 6% 18%	4406
	11th to 20th	Night	21% 15% 6% 9% 5% 3 4 4 5% 8% 20%	4420
	21st to end	Night	17% 17% 7% 11% 7% 3 5% 5% 5% 5% 17%	4800
February	1st to 10th	Night	10% 12% 5% 9% 7% 3 5% 5% 6% 6% 31%	2470
	11th to 20th	Night	9% 8% 4 7% 6% 3 6% 5% 6% 7% 39%	2315
	21st to end	Night	8% 11% 4 8% 6% 3 5% 5% 7% 9% 34%	1776
March	1st to 10th	Night	9% 8% 5% 8% 6% 4 5% 7% 6% 9% 33%	2160
	11th to 20th	Night	8% 7% 3 7% 7% 4 6% 6% 7% 9% 37%	2009
	21st to end	Night	7% 7% 4 8% 7% 4 7% 6% 6% 9% 34%	2050
April	1st to 10th	Night	8% 7% 3 6% 6% 4 5% 5% 7% 9% 41%	1800
	11th to 20th	Night	7% 6% 3 6% 6% 3 5% 4 6% 7% 48%	1779
	21st to end	Night	6% 5% 3 4 5% 3 5% 5% 7% 8% 48%	1675
May	1st to 10th	Night	4 3 1 4 5% 3 4 5% 6% 6% 57%	1440
	11th to 20th	Night	7% 4 2 4 5% 3 5% 5% 6% 9% 50%	1416
	21st to end	Night	5% 5% 2 5% 5% 3 5% 5% 7% 9% 49%	1552
June	1st to 10th	Night	8% 3 2 4 6% 2 4 4 7% 9% 51%	1440
	11th to 20th	Night	5% 4 2 4 3 2 3 4 4 7% 62%	1440
	21st to end	Night	3 3 1 3 3 3 3 3 4 4 70%	1440
July	1st to 10th	Night	2 2 1 2 2 1 3 2 3 5% 77%	1440
	11th to 20th	Night	1 1 1 1 2 1 3 3 3 4 80%	1440
	21st to end	Night	1 1 2 2 1 1 2 3 4 84%	1576
August	1st to 10th	Night	2 2 1 2 2 1 2 3 3 6% 75%	1444
	11th to 20th	Night	3 2 1 1 2 2 2 3 3 4 77%	1615
	21st to end	Night	1 2 1 2 3 1 2 3 4 6% 75%	1980
September	1st to 10th	Night	1 1 1 2 2 1 2 3 3 6% 79%	1800
	11th to 20th	Night	3 3 1 3 3 2 4 4 5% 6% 65%	1800
	21st to end	Night	5% 4 1 3 4 2 4 4 5% 7% 61%	2017
October	1st to 10th	Night	6% 5% 2 5% 5% 2 4 4 5% 6% 56%	2160
	11th to 20th	Night	6% 5% 2 5% 5% 4 4 4 6% 7% 51%	2160
	21st to end	Night	9% 7% 3 5% 5% 3 5% 4 5% 7% 47%	2519
November	1st to 10th	Night	12% 8% 3 6% 6% 4 4 6% 7% 8% 36%	2405
	11th to 20th	Night	13% 12% 4 7% 7% 4 6% 6% 6% 6% 29%	2650
	21st to end	Night	9% 10% 5% 9% 7% 4 6% 5% 5% 7% 34%	2660
December	1st to 10th	Night	12% 13% 7% 10% 6% 4 6% 5% 5% 5% 27%	2660
	11th to 20th	Night	15% 17% 7% 12% 8% 4 6% 5% 5% 6% 16%	3276
	21st to end	Night	14% 15% 8% 9% 7% 4 5% 4 4 7% 23%	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	66% 11% 10% 11% 2	2539
	11th to 20th	Day	65% 8% 15% 10% 2	2540
	21st to end	Day	69% 8% 12% 8% 2	2856
February	1st to 10th	Day	54% 9% 17% 16% 4	1710
	11th to 20th	Day	49% 9% 15% 20% 7%	1634
	21st to end	Day	49% 10% 15% 16% 10%	1480
March	1st to 10th	Day	49% 9% 14% 19% 9% 1	1800
	11th to 20th	Day	51% 7% 12% 24% 5%	1948
	21st to end	Day	50% 10% 15% 19% 6%	2305
April	1st to 10th	Day	42% 10% 14% 22% 12%	2160
	11th to 20th	Day	41% 7% 15% 20% 14% 3	2132
	21st to end	Day	31% 8% 14% 28% 16% 2	2282
May	1st to 10th	Day	29% 7% 12% 31% 19% 2	2520
	11th to 20th	Day	36% 6% 13% 26% 16% 3	2480
	21st to end	Day	33% 8% 15% 28% 15% 1	2724
June	1st to 10th	Day	32% 8% 13% 29% 16% 3	2520
	11th to 20th	Day	26% 6% 13% 36% 17% 2	2520
	21st to end	Day	17% 4 11% 34% 25% 10%	2520
July	1st to 10th	Day	11% 4 8% 25% 31% 20%	2451
	11th to 20th	Day	12% 4 7% 17% 33% 27%	2445
	21st to end	Day	8% 2 4 16% 42% 28%	2589
August	1st to 10th	Day	12% 3 8% 25% 34% 18%	2474
	11th to 20th	Day	11% 3 7% 26% 36% 18%	2284
	21st to end	Day	14% 4 7% 32% 34% 9%	2376
September	1st to 10th	Day	12% 3 8% 30% 29% 16%	2160
	11th to 20th	Day	23% 6% 10% 27% 25% 9%	2160
	21st to end	Day	29% 5% 13% 28% 20% 6%	1940
October	1st to 10th	Day	32% 6% 13% 27% 19% 3	1800
	11th to 20th	Day	33% 8% 16% 26% 15% 2	1800
	21st to end	Day	42% 9% 15% 24% 10% 1	1836
November	1st to 10th	Day	48% 8% 16% 20% 6% 1	1674
	11th to 20th	Day	58% 9% 15% 15% 3	1528
	21st to end	Day	52% 8% 17% 15% 7% 1	1520
December	1st to 10th	Day	56% 9% 13% 16% 5%	1520
	11th to 20th	Day	67% 11% 12% 9% 2	1928
	21st to end	Day	67% 9% 11% 10% 2	2794
January	1st to 10th	Night	66% 12% 10% 9% 3	4406
	11th to 20th	Night	63% 8% 14% 12% 3	4420
	21st to end	Night	67% 10% 12% 9% 2	4800
February	1st to 10th	Night	51% 9% 19% 17% 4	2470
	11th to 20th	Night	44% 9% 17% 22% 9%	2317
	21st to end	Night	48% 9% 16% 17% 9% 1	1776
March	1st to 10th	Night	47% 8% 16% 21% 8% 1	2160
	11th to 20th	Night	43% 8% 16% 24% 7% 1	2009
	21st to end	Night	45% 11% 17% 21% 6%	2050
April	1st to 10th	Night	40% 9% 17% 24% 10% 1	1800
	11th to 20th	Night	37% 7% 16% 26% 12% 3	1779
	21st to end	Night	33% 10% 15% 26% 12% 3	1675
May	1st to 10th	Night	27% 6% 16% 33% 16% 2	1440
	11th to 20th	Night	31% 8% 17% 27% 15% 3	1416
	21st to end	Night	31% 9% 21% 25% 13% 1	1552
June	1st to 10th	Night	31% 9% 13% 32% 12% 3	1440
	11th to 20th	Night	24% 6% 15% 37% 17% 1	1440
	21st to end	Night	19% 5% 10% 36% 23% 8%	1440
July	1st to 10th	Night	12% 2 12% 25% 31% 19%	1400
	11th to 20th	Night	10% 5% 9% 20% 29% 27%	1392
	21st to end	Night	7% 2 4 17% 40% 29%	1488
August	1st to 10th	Night	13% 3 7% 26% 35% 17%	1436
	11th to 20th	Night	13% 3 7% 25% 36% 16%	1615
	21st to end	Night	13% 3 8% 29% 37% 11%	1980
September	1st to 10th	Night	10% 3 11% 30% 29% 17%	1800
	11th to 20th	Night	20% 5% 11% 30% 21% 14%	1800
	21st to end	Night	23% 5% 13% 29% 23% 8%	2017
October	1st to 10th	Night	30% 5% 10% 27% 24% 3	2160
	11th to 20th	Night	32% 7% 14% 28% 16% 3	2160
	21st to end	Night	37% 7% 14% 24% 17% 1	2519
November	1st to 10th	Night	45% 8% 13% 25% 9%	2405
	11th to 20th	Night	54% 9% 13% 20% 4	2650
	21st to end	Night	48% 8% 18% 19% 7%	2660
December	1st to 10th	Night	58% 10% 14% 15% 4	2660
	11th to 20th	Night	66% 9% 14% 9% 2	3276
	21st to end	Night	61% 8% 14% 12% 5%	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% 17% 21% 22% 11% 4	180
	11th to 20th	Day	28% 11% 22% 25% 13% 2	180
	21st to end	Day	19% 14% 24% 28% 15%	234
February	1st to 10th	Day	22% 17% 26% 26% 9% 1	370
	11th to 20th	Day	23% 19% 24% 21% 12% 1	354
	21st to end	Day	18% 18% 29% 26% 7% 2	346
March	1st to 10th	Day	18% 17% 29% 25% 10% 2	420
	11th to 20th	Day	17% 19% 25% 25% 14% 1	420
	21st to end	Day	18% 19% 31% 22% 9%	462
April	1st to 10th	Day	20% 21% 30% 18% 9% 3	420
	11th to 20th	Day	14% 25% 32% 17% 9% 3	412
	21st to end	Day	11% 26% 32% 21% 9% 2	420
May	1st to 10th	Day	12% 18% 31% 26% 11% 3	423
	11th to 20th	Day	16% 14% 28% 24% 15% 4	448
	21st to end	Day	12% 14% 31% 27% 13% 4	485
June	1st to 10th	Day	11% 22% 23% 25% 14% 4	450
	11th to 20th	Day	12% 24% 31% 22% 9% 2	450
	21st to end	Day	6% 14% 31% 30% 15% 4	450
July	1st to 10th	Day	2 10% 41% 31% 14% 1	446
	11th to 20th	Day	4 14% 36% 29% 16% 2	444
	21st to end	Day	2 9% 30% 31% 20% 7%	487
August	1st to 10th	Day	5% 9% 29% 24% 23% 10%	447
	11th to 20th	Day	3 6% 25% 31% 25% 10%	437
	21st to end	Day	5% 12% 30% 27% 20% 6%	495
September	1st to 10th	Day	4 10% 27% 33% 20% 7%	450
	11th to 20th	Day	7% 11% 30% 29% 19% 4	450
	21st to end	Day	8% 16% 26% 27% 20% 4	450
October	1st to 10th	Day	11% 16% 26% 22% 20% 5%	450
	11th to 20th	Day	11% 16% 23% 26% 18% 6%	450
	21st to end	Day	16% 19% 26% 20% 15% 5%	351
November	1st to 10th	Day	19% 17% 27% 26% 11% 1	270
	11th to 20th	Day	17% 16% 30% 20% 13% 4	183
	21st to end	Day	20% 10% 28% 27% 13% 2	180
December	1st to 10th	Day	20% 18% 16% 28% 10% 8%	180
	11th to 20th	Day	17% 14% 28% 31% 10% 1	180
	21st to end	Day	15% 21% 23% 30% 10% 1	198
January	1st to 10th	Night	24% 13% 22% 27% 12% 1	760
	11th to 20th	Night	22% 10% 19% 29% 17% 3	760
	21st to end	Night	21% 9% 17% 32% 19% 2	836
February	1st to 10th	Night	18% 15% 18% 33% 14% 2	760
	11th to 20th	Night	14% 16% 20% 34% 15% 1	722
	21st to end	Night	18% 14% 23% 34% 9% 2	592
March	1st to 10th	Night	13% 12% 24% 35% 15% 1	720
	11th to 20th	Night	11% 11% 24% 36% 17% 1	720
	21st to end	Night	13% 17% 29% 27% 13% 1	792
April	1st to 10th	Night	13% 15% 29% 28% 13% 2	720
	11th to 20th	Night	11% 20% 27% 25% 14% 3	711
	21st to end	Night	10% 18% 36% 23% 13% 1	595
May	1st to 10th	Night	8% 14% 30% 30% 15% 2	360
	11th to 20th	Night	10% 9% 29% 31% 18% 3	354
	21st to end	Night	8% 11% 32% 31% 15% 3	389
June	1st to 10th	Night	11% 15% 36% 24% 14% 1	360
	11th to 20th	Night	9% 21% 37% 25% 8% 1	360
	21st to end	Night	5% 15% 34% 28% 17% 1	360
July	1st to 10th	Night	3 11% 38% 31% 16% 1	350
	11th to 20th	Night	1 10% 44% 30% 11% 2	348
	21st to end	Night	1 9% 33% 34% 22% 2	394
August	1st to 10th	Night	3 7% 33% 33% 19% 4	370
	11th to 20th	Night	4 5% 22% 31% 29% 9%	547
	21st to end	Night	3 11% 30% 30% 23% 4	792
September	1st to 10th	Night	2 8% 27% 32% 28% 3	720
	11th to 20th	Night	4 7% 25% 30% 29% 6%	720
	21st to end	Night	8% 10% 20% 32% 28% 4	720
October	1st to 10th	Night	8% 8% 22% 38% 23% 2	720
	11th to 20th	Night	8% 11% 21% 31% 24% 4	720
	21st to end	Night	13% 10% 23% 32% 17% 4	792
November	1st to 10th	Night	17% 10% 21% 38% 15% 1	740
	11th to 20th	Night	21% 14% 20% 29% 13% 3	760
	21st to end	Night	13% 11% 21% 34% 18% 3	760
December	1st to 10th	Night	18% 10% 22% 30% 18% 3	760
	11th to 20th	Night	21% 9% 21% 35% 13% 2	760
	21st to end	Night	22% 12% 22% 33% 11% 1	836

Page generated at 2024-02-12 03:35:37. Version ac07

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