Dolen
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dolen clear sky chart from 2005-11-06 to 2024-11-08.

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	13% 6% 2 6% 5% 5% 5% 4 6% 8% 39%	101066
	Night	14% 7% 2 5% 4 4 4 3 5% 7% 45%	98117
Transparency	Day	40% 7% 11% 18% 17% 7%	104740
	Night	37% 6% 12% 19% 18% 9%	102570
Seeing	Day	14% 9% 22% 26% 21% 8%	14922
	Night	16% 8% 23% 32% 19% 2	24735

By Month

Percentage Cloud Cover SE (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	20% 10% 2 5% 3 3 3 3 4 5% 42%	2847
	11th to 20th	Day	18% 7% 2 4 3 2 2 2 4 4 52%	2850
	21st to end	Day	24% 7% 3 6% 3 3 3 2 5% 8% 35%	3135
February	1st to 10th	Day	22% 9% 4 6% 5% 3 4 2 4 5% 37%	1737
	11th to 20th	Day	21% 8% 3 7% 4 3 4 3 4 4 39%	1896
	21st to end	Day	22% 7% 3 7% 4 3 4 3 4 4 39%	1727
March	1st to 10th	Day	19% 9% 4 9% 5% 5% 4 4 5% 6% 30%	3436
	11th to 20th	Day	20% 8% 3 8% 5% 4 5% 4 6% 7% 30%	3480
	21st to end	Day	17% 8% 2 7% 4 5% 4 3 4 6% 39%	3814
April	1st to 10th	Day	15% 8% 3 8% 5% 5% 4 4 5% 6% 38%	2090
	11th to 20th	Day	17% 7% 2 6% 5% 4 4 4 6% 6% 38%	2254
	21st to end	Day	11% 7% 3 6% 5% 4 5% 3 6% 7% 43%	2280
May	1st to 10th	Day	18% 8% 3 8% 7% 5% 5% 4 5% 7% 29%	3787
	11th to 20th	Day	13% 6% 2 6% 4 5% 4 4 6% 7% 42%	4082
	21st to end	Day	9% 6% 3 8% 6% 6% 6% 5% 7% 11% 34%	4477
June	1st to 10th	Day	7% 5% 2 6% 7% 7% 6% 6% 8% 10% 36%	2470
	11th to 20th	Day	5% 4 2 5% 6% 6% 7% 6% 8% 12% 37%	2470
	21st to end	Day	6% 6% 3 9% 8% 7% 8% 7% 9% 9% 30%	2470
July	1st to 10th	Day	9% 4 2 7% 7% 6% 8% 7% 8% 11% 33%	4120
	11th to 20th	Day	7% 7% 3 8% 7% 7% 7% 6% 8% 11% 28%	4120
	21st to end	Day	16% 9% 3 7% 5% 5% 5% 5% 8% 10% 26%	4465
August	1st to 10th	Day	2 2 1 3 3 4 4 4 6% 10% 60%	4104
	11th to 20th	Day	3 3 1 4 4 4 5% 5% 8% 14% 48%	3833
	21st to end	Day	9% 4 2 7% 6% 6% 6% 6% 7% 9% 37%	4180
September	1st to 10th	Day	8% 5% 2 8% 6% 6% 6% 6% 7% 9% 37%	2132
	11th to 20th	Day	15% 6% 2 6% 6% 6% 5% 4 5% 6% 38%	2090
	21st to end	Day	8% 4 2 6% 5% 5% 5% 4 5% 7% 49%	2090
October	1st to 10th	Day	7% 4 2 5% 5% 5% 4 2 4 6% 57%	1939
	11th to 20th	Day	10% 4 2 5% 4 4 4 4 4 7% 53%	1900
	21st to end	Day	14% 5% 1 5% 3 3 3 3 4 6% 52%	2090
November	1st to 10th	Day	11% 5% 2 5% 4 6% 5% 3 4 5% 47%	1928
	11th to 20th	Day	11% 7% 2 7% 4 4 4 3 4 5% 48%	1900
	21st to end	Day	18% 7% 2 7% 4 4 3 3 4 5% 43%	1867
December	1st to 10th	Day	16% 9% 3 5% 5% 4 3 4 5% 6% 40%	1710
	11th to 20th	Day	15% 8% 2 6% 5% 5% 4 4 5% 6% 40%	2161
	21st to end	Day	18% 7% 2 6% 4 4 4 3 4 5% 44%	3135
January	1st to 10th	Night	17% 8% 2 6% 3 3 3 3 4 6% 45%	4108
	11th to 20th	Night	20% 6% 2 5% 3 2 2 2 3 4 51%	4120
	21st to end	Night	24% 9% 3 5% 3 3 3 2 4 6% 37%	4532
February	1st to 10th	Night	19% 9% 3 6% 3 3 3 3 5% 6% 40%	2458
	11th to 20th	Night	22% 8% 3 6% 3 3 3 2 4 5% 41%	2168
	21st to end	Night	21% 9% 2 6% 4 3 4 3 4 4 39%	1727
March	1st to 10th	Night	25% 11% 3 6% 5% 4 3 3 4 6% 30%	3419
	11th to 20th	Night	23% 10% 4 8% 4 4 4 3 4 6% 30%	3480
	21st to end	Night	15% 7% 2 7% 5% 4 4 4 4 5% 42%	3817
April	1st to 10th	Night	15% 7% 3 8% 4 4 4 5% 5% 7% 39%	2090
	11th to 20th	Night	17% 6% 2 5% 4 4 4 3 5% 7% 42%	1875
	21st to end	Night	15% 6% 2 6% 4 4 4 3 5% 6% 45%	1900
May	1st to 10th	Night	24% 10% 3 7% 4 4 4 4 5% 8% 28%	3104
	11th to 20th	Night	15% 8% 3 6% 4 4 4 3 5% 6% 43%	2823
	21st to end	Night	12% 7% 3 7% 5% 5% 4 5% 7% 10% 36%	3090
June	1st to 10th	Night	6% 4 2 5% 3 4 5% 4 6% 11% 51%	1710
	11th to 20th	Night	4 3 1 4 3 4 4 4 7% 13% 54%	1710
	21st to end	Night	6% 5% 2 5% 5% 4 5% 5% 7% 11% 46%	1710
July	1st to 10th	Night	7% 5% 2 4 5% 4 4 5% 9% 14% 42%	2850
	11th to 20th	Night	4 5% 2 7% 4 5% 5% 5% 7% 12% 43%	2850
	21st to end	Night	12% 7% 3 8% 5% 4 5% 5% 6% 9% 37%	3098
August	1st to 10th	Night	1 1 1 2 2 3 3 3 5% 11% 67%	2836
	11th to 20th	Night	2 2 1 2 2 2 3 4 7% 13% 61%	2999
	21st to end	Night	7% 3 2 5% 4 5% 6% 5% 8% 11% 45%	3476
September	1st to 10th	Night	6% 4 2 6% 5% 5% 5% 3 7% 10% 47%	2042
	11th to 20th	Night	11% 6% 2 7% 4 4 5% 4 6% 8% 42%	2090
	21st to end	Night	7% 4 2 4 4 3 4 3 6% 8% 54%	2090
October	1st to 10th	Night	5% 3 2 4 3 3 4 4 5% 7% 60%	2220
	11th to 20th	Night	10% 4 1 4 3 2 3 3 4 7% 60%	2280
	21st to end	Night	13% 5% 2 4 3 3 2 2 3 4 58%	2508
November	1st to 10th	Night	12% 5% 1 5% 4 4 3 3 4 6% 52%	2311
	11th to 20th	Night	11% 6% 2 5% 4 4 4 3 5% 6% 50%	2280
	21st to end	Night	17% 6% 2 5% 4 4 4 3 5% 5% 45%	2308
December	1st to 10th	Night	18% 8% 2 5% 4 3 4 3 5% 6% 41%	2470
	11th to 20th	Night	18% 8% 3 6% 4 3 4 2 4 5% 43%	3036
	21st to end	Night	17% 8% 2 5% 3 3 3 3 4 5% 45%	4532

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	45% 4 5% 16% 22% 9%	2848
	11th to 20th	Day	37% 4 4 19% 28% 8%	2850
	21st to end	Day	49% 3 4 17% 17% 10%	3135
February	1st to 10th	Day	50% 4 5% 13% 17% 10%	1737
	11th to 20th	Day	50% 4 6% 14% 16% 11%	1906
	21st to end	Day	48% 5% 8% 13% 16% 10%	1727
March	1st to 10th	Day	54% 5% 9% 12% 15% 5%	3436
	11th to 20th	Day	51% 6% 9% 15% 13% 6%	3480
	21st to end	Day	45% 5% 7% 16% 22% 4	3814
April	1st to 10th	Day	47% 6% 7% 15% 17% 8%	2090
	11th to 20th	Day	45% 5% 8% 15% 16% 10%	2254
	21st to end	Day	40% 6% 9% 18% 22% 6%	2280
May	1st to 10th	Day	53% 7% 9% 17% 10% 4	3822
	11th to 20th	Day	40% 6% 9% 18% 23% 3	4086
	21st to end	Day	41% 9% 12% 27% 10% 1	4489
June	1st to 10th	Day	40% 10% 15% 20% 14% 1	2470
	11th to 20th	Day	36% 10% 16% 21% 14% 2	2470
	21st to end	Day	45% 12% 16% 20% 8%	2470
July	1st to 10th	Day	41% 11% 25% 19% 3	4056
	11th to 20th	Day	46% 11% 17% 19% 7%	4051
	21st to end	Day	50% 11% 17% 17% 4 1	4325
August	1st to 10th	Day	18% 8% 14% 35% 24%	4090
	11th to 20th	Day	24% 9% 30% 29% 6% 1	3871
	21st to end	Day	41% 11% 16% 17% 15% 1	4179
September	1st to 10th	Day	42% 10% 12% 16% 14% 6%	2132
	11th to 20th	Day	45% 8% 14% 14% 15% 5%	2090
	21st to end	Day	34% 7% 12% 19% 17% 11%	2090
October	1st to 10th	Day	20% 4 6% 13% 18% 39%	3225
	11th to 20th	Day	20% 4 4 17% 34% 20%	3140
	21st to end	Day	27% 5% 5% 13% 39% 13%	3428
November	1st to 10th	Day	38% 5% 9% 17% 19% 11%	1928
	11th to 20th	Day	38% 5% 7% 15% 23% 12%	1900
	21st to end	Day	45% 4 6% 17% 18% 11%	1867
December	1st to 10th	Day	45% 6% 7% 17% 18% 7%	1710
	11th to 20th	Day	44% 4 7% 14% 20% 10%	2159
	21st to end	Day	42% 5% 5% 15% 24% 10%	3135
January	1st to 10th	Night	41% 4 6% 19% 20% 10%	4108
	11th to 20th	Night	39% 3 5% 18% 27% 9%	4120
	21st to end	Night	50% 3 4 17% 17% 10%	4532
February	1st to 10th	Night	46% 4 6% 14% 16% 13%	2458
	11th to 20th	Night	46% 4 7% 13% 19% 11%	2168
	21st to end	Night	49% 4 6% 13% 16% 13%	1727
March	1st to 10th	Night	56% 4 7% 14% 13% 6%	3419
	11th to 20th	Night	55% 6% 8% 13% 13% 5%	3480
	21st to end	Night	42% 6% 9% 14% 22% 6%	3817
April	1st to 10th	Night	43% 6% 9% 16% 15% 10%	2090
	11th to 20th	Night	43% 5% 8% 16% 15% 12%	1875
	21st to end	Night	39% 6% 7% 20% 21% 6%	1900
May	1st to 10th	Night	56% 5% 10% 14% 10% 4	3134
	11th to 20th	Night	41% 7% 10% 17% 22% 3	2824
	21st to end	Night	39% 9% 18% 25% 8% 1	3099
June	1st to 10th	Night	25% 9% 19% 31% 16%	1710
	11th to 20th	Night	21% 10% 19% 30% 17% 3	1710
	21st to end	Night	30% 11% 20% 28% 10% 1	1710
July	1st to 10th	Night	31% 10% 34% 22% 3	2805
	11th to 20th	Night	30% 11% 27% 24% 8%	2796
	21st to end	Night	41% 12% 21% 22% 4	2999
August	1st to 10th	Night	11% 6% 20% 42% 21%	2826
	11th to 20th	Night	15% 7% 36% 35% 7%	3027
	21st to end	Night	30% 14% 20% 23% 11% 2	3476
September	1st to 10th	Night	30% 10% 21% 21% 12% 6%	2042
	11th to 20th	Night	38% 8% 16% 17% 15% 6%	2090
	21st to end	Night	28% 6% 13% 22% 19% 12%	2090
October	1st to 10th	Night	17% 4 7% 18% 16% 38%	3701
	11th to 20th	Night	16% 3 4 23% 32% 22%	3779
	21st to end	Night	24% 4 4 13% 40% 15%	4120
November	1st to 10th	Night	32% 4 12% 19% 22% 11%	2311
	11th to 20th	Night	35% 5% 9% 17% 22% 11%	2280
	21st to end	Night	41% 4 8% 17% 19% 11%	2308
December	1st to 10th	Night	43% 5% 7% 19% 15% 10%	2470
	11th to 20th	Night	44% 4 7% 11% 20% 14%	3037
	21st to end	Night	42% 4 7% 13% 27% 8%	4532

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% 37% 15% 5% 1	270
	11th to 20th	Day	28% 15% 31% 20% 4 1	270
	21st to end	Day	24% 21% 33% 18% 4	297
February	1st to 10th	Day	31% 20% 33% 13% 4	270
	11th to 20th	Day	29% 19% 33% 16% 2	270
	21st to end	Day	28% 25% 37% 8% 1	225
March	1st to 10th	Day	27% 20% 31% 17% 5%	270
	11th to 20th	Day	20% 32% 31% 14% 3	270
	21st to end	Day	23% 18% 41% 14% 4	297
April	1st to 10th	Day	23% 18% 37% 20% 2	270
	11th to 20th	Day	26% 17% 24% 21% 11%	452
	21st to end	Day	15% 16% 35% 23% 9% 2	460
May	1st to 10th	Day	19% 14% 32% 24% 10% 1	472
	11th to 20th	Day	12% 10% 29% 31% 16% 2	675
	21st to end	Day	9% 9% 30% 32% 16% 3	734
June	1st to 10th	Day	9% 3 18% 33% 29% 9%	680
	11th to 20th	Day	8% 2 20% 36% 26% 9%	680
	21st to end	Day	8% 1 16% 32% 30% 13%	680
July	1st to 10th	Day	7% 3 10% 28% 35% 17%	671
	11th to 20th	Day	6% 1 5% 29% 41% 18%	668
	21st to end	Day	8% 2 6% 29% 39% 17%	739
August	1st to 10th	Day	3 1 5% 27% 45% 19%	676
	11th to 20th	Day	5% 2 21% 48% 23%	547
	21st to end	Day	12% 2 6% 18% 35% 26%	539
September	1st to 10th	Day	8% 2 9% 26% 37% 17%	342
	11th to 20th	Day	12% 3 13% 29% 33% 10%	300
	21st to end	Day	11% 2 12% 34% 31% 10%	300
October	1st to 10th	Day	6% 5% 20% 43% 21% 5%	300
	11th to 20th	Day	9% 5% 24% 42% 14% 6%	300
	21st to end	Day	20% 9% 26% 25% 16% 4	330
November	1st to 10th	Day	16% 9% 26% 32% 15% 1	291
	11th to 20th	Day	15% 12% 32% 31% 8% 1	270
	21st to end	Day	23% 19% 30% 19% 8% 2	270
December	1st to 10th	Day	18% 12% 34% 24% 7% 4	270
	11th to 20th	Day	24% 16% 34% 22% 3 1	270
	21st to end	Day	22% 18% 34% 19% 5% 1	297
January	1st to 10th	Night	23% 13% 30% 28% 6%	950
	11th to 20th	Night	24% 13% 28% 28% 7% 1	950
	21st to end	Night	25% 11% 29% 30% 5%	1045
February	1st to 10th	Night	25% 17% 30% 25% 4	938
	11th to 20th	Night	29% 12% 30% 24% 5%	694
	21st to end	Night	25% 17% 34% 22% 1	471
March	1st to 10th	Night	27% 11% 33% 24% 5%	570
	11th to 20th	Night	19% 13% 35% 27% 5%	570
	21st to end	Night	19% 10% 39% 24% 8%	627
April	1st to 10th	Night	18% 11% 39% 25% 6%	570
	11th to 20th	Night	20% 12% 33% 27% 8%	563
	21st to end	Night	20% 12% 31% 30% 8%	570
May	1st to 10th	Night	18% 10% 34% 30% 7%	570
	11th to 20th	Night	15% 6% 29% 34% 15% 1	561
	21st to end	Night	7% 5% 29% 38% 19% 2	617
June	1st to 10th	Night	6% 3 15% 41% 32% 4	570
	11th to 20th	Night	5% 2 20% 45% 26% 3	570
	21st to end	Night	7% 3 12% 38% 35% 6%	570
July	1st to 10th	Night	5% 2 7% 42% 34% 10%	555
	11th to 20th	Night	4 1 6% 40% 42% 7%	552
	21st to end	Night	5% 5% 41% 43% 6%	624
August	1st to 10th	Night	1 5% 42% 47% 4	567
	11th to 20th	Night	5% 4 38% 45% 7%	564
	21st to end	Night	7% 1 5% 31% 47% 9%	627
September	1st to 10th	Night	8% 2 7% 29% 47% 8%	570
	11th to 20th	Night	13% 2 8% 28% 42% 7%	570
	21st to end	Night	8% 1 11% 35% 39% 6%	570
October	1st to 10th	Night	6% 3 14% 35% 38% 4	700
	11th to 20th	Night	11% 4 24% 38% 21% 1	760
	21st to end	Night	13% 8% 24% 33% 20% 2	836
November	1st to 10th	Night	13% 5% 25% 35% 21% 1	771
	11th to 20th	Night	14% 10% 24% 37% 14% 1	760
	21st to end	Night	20% 10% 28% 28% 13% 1	788
December	1st to 10th	Night	23% 10% 26% 28% 12% 1	950
	11th to 20th	Night	27% 11% 27% 29% 6%	950
	21st to end	Night	23% 12% 29% 28% 7%	1045

Page generated at 2024-11-05 07:15:53. Version ac07

Copyright © 2024 Attilla Danko.