Dievseta
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dievseta clear sky chart from 2005-11-06 to 2026-07-01.

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	12% 9% 3 8% 5% 5% 5% 4 6% 7% 37%	138432
	Night	12% 10% 4 9% 5% 4 5% 4 5% 6% 36%	134252
Transparency	Day	44% 5% 12% 25% 13% 1	141918
	Night	46% 5% 12% 23% 13% 1	138842
Seeing	Day	18% 13% 31% 24% 12% 3	18240
	Night	17% 11% 32% 29% 10% 1	28122

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	8% 13% 6% 16% 8% 6% 5% 4 4 5% 25%	4691
	11th to 20th	Day	5% 11% 7% 12% 5% 5% 6% 8% 9% 7% 23%	4710
	21st to end	Day	8% 11% 6% 10% 5% 5% 6% 3 5% 6% 35%	5496
February	1st to 10th	Day	8% 13% 5% 10% 6% 5% 6% 5% 6% 5% 31%	1890
	11th to 20th	Day	9% 11% 4 8% 6% 5% 5% 4 6% 6% 35%	1886
	21st to end	Day	11% 13% 4 9% 7% 5% 4 3 6% 7% 32%	1730
March	1st to 10th	Day	14% 9% 2 4 3 3 3 3 4 6% 48%	4580
	11th to 20th	Day	11% 7% 3 9% 4 4 4 4 5% 8% 42%	5085
	21st to end	Day	22% 12% 3 9% 4 4 4 4 4 5% 29%	5906
April	1st to 10th	Day	17% 13% 4 8% 5% 5% 4 3 4 6% 31%	2520
	11th to 20th	Day	19% 11% 3 9% 4 4 4 4 4 5% 31%	2494
	21st to end	Day	20% 12% 2 8% 4 4 4 4 5% 6% 31%	2562
May	1st to 10th	Day	12% 6% 2 6% 4 5% 5% 4 6% 7% 43%	8212
	11th to 20th	Day	13% 7% 2 7% 5% 4 4 4 5% 7% 41%	8222
	21st to end	Day	15% 7% 3 7% 5% 4 5% 4 5% 7% 39%	9047
June	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 6% 9% 42%	2940
	11th to 20th	Day	14% 6% 3 7% 5% 5% 4 3 6% 8% 38%	2940
	21st to end	Day	13% 7% 3 6% 5% 5% 5% 4 7% 8% 37%	2940
July	1st to 10th	Day	9% 5% 2 7% 4 4 5% 5% 7% 11% 41%	6361
	11th to 20th	Day	7% 4 2 5% 4 4 5% 5% 7% 10% 47%	6360
	21st to end	Day	9% 7% 3 7% 5% 5% 4 4 6% 7% 42%	6924
August	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 5% 6% 8% 39%	4418
	11th to 20th	Day	13% 6% 2 6% 3 5% 5% 4 5% 8% 44%	4082
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 3 6% 9% 42%	4312
September	1st to 10th	Day	12% 6% 3 6% 3 4 5% 4 6% 8% 44%	2400
	11th to 20th	Day	11% 5% 2 6% 4 5% 5% 4 5% 8% 45%	2390
	21st to end	Day	12% 7% 3 7% 4 3 4 4 6% 7% 42%	2150
October	1st to 10th	Day	13% 7% 2 6% 4 5% 4 3 5% 6% 46%	2000
	11th to 20th	Day	16% 12% 2 7% 4 4 4 4 5% 8% 35%	2000
	21st to end	Day	17% 11% 3 8% 4 4 4 2 4 6% 38%	2055
November	1st to 10th	Day	13% 10% 3 7% 4 5% 5% 3 4 7% 41%	1852
	11th to 20th	Day	14% 13% 5% 9% 6% 4 4 3 5% 8% 30%	1749
	21st to end	Day	12% 12% 3 9% 6% 4 4 3 4 5% 37%	1680
December	1st to 10th	Day	7% 9% 4 13% 7% 8% 6% 5% 6% 6% 29%	2690
	11th to 20th	Day	13% 16% 5% 10% 7% 5% 5% 3 5% 6% 27%	3088
	21st to end	Day	19% 21% 8% 13% 6% 4 4 3 4 4 15%	4070
January	1st to 10th	Night	10% 12% 6% 14% 8% 5% 4 3 4 5% 31%	8232
	11th to 20th	Night	7% 13% 6% 16% 8% 6% 9% 6% 7% 4 19%	8280
	21st to end	Night	8% 13% 6% 10% 6% 6% 5% 4 6% 6% 30%	8702
February	1st to 10th	Night	8% 13% 5% 12% 6% 5% 6% 4 5% 5% 31%	2730
	11th to 20th	Night	9% 9% 4 8% 5% 5% 5% 4 5% 7% 38%	2620
	21st to end	Night	13% 10% 3 9% 7% 4 4 4 6% 6% 33%	2076
March	1st to 10th	Night	12% 7% 3 7% 4 4 4 3 5% 6% 44%	5493
	11th to 20th	Night	9% 9% 3 8% 5% 5% 5% 4 5% 7% 39%	5138
	21st to end	Night	22% 12% 4 10% 4 4 3 3 4 6% 29%	5265
April	1st to 10th	Night	18% 11% 3 7% 5% 4 4 3 5% 6% 34%	2100
	11th to 20th	Night	19% 10% 3 8% 3 3 3 3 5% 5% 37%	2075
	21st to end	Night	16% 10% 3 7% 4 4 4 3 4 8% 36%	2054
May	1st to 10th	Night	11% 7% 2 7% 5% 4 5% 4 5% 8% 43%	4671
	11th to 20th	Night	12% 6% 2 6% 5% 4 5% 3 5% 6% 46%	4670
	21st to end	Night	14% 9% 3 8% 5% 4 5% 4 5% 7% 36%	5139
June	1st to 10th	Night	11% 4 3 6% 4 5% 4 4 6% 7% 47%	1680
	11th to 20th	Night	11% 6% 3 8% 4 3 5% 4 6% 8% 42%	1680
	21st to end	Night	9% 5% 2 6% 5% 4 4 4 7% 9% 46%	1680
July	1st to 10th	Night	11% 6% 3 7% 3 4 5% 3 6% 9% 44%	3618
	11th to 20th	Night	8% 5% 2 5% 4 4 4 3 5% 7% 54%	3617
	21st to end	Night	5% 5% 3 6% 4 5% 5% 5% 7% 8% 48%	3947
August	1st to 10th	Night	9% 6% 2 7% 4 5% 4 4 6% 7% 46%	2725
	11th to 20th	Night	10% 6% 2 6% 4 4 4 4 5% 7% 48%	2972
	21st to end	Night	10% 6% 2 6% 4 4 4 3 6% 7% 49%	3586
September	1st to 10th	Night	9% 5% 3 7% 3 3 4 3 5% 6% 51%	2000
	11th to 20th	Night	11% 6% 2 5% 3 3 4 3 5% 8% 50%	2000
	21st to end	Night	12% 7% 2 5% 4 3 4 3 5% 5% 51%	2235
October	1st to 10th	Night	12% 6% 2 5% 3 3 4 3 5% 6% 50%	2400
	11th to 20th	Night	16% 8% 3 6% 4 3 4 4 5% 7% 40%	2400
	21st to end	Night	17% 10% 3 7% 5% 4 4 4 5% 6% 36%	2785
November	1st to 10th	Night	14% 9% 3 6% 4 4 3 3 5% 6% 41%	2666
	11th to 20th	Night	12% 13% 4 10% 6% 4 5% 3 4 6% 33%	2867
	21st to end	Night	14% 12% 4 10% 5% 4 3 3 4 5% 35%	2940
December	1st to 10th	Night	8% 9% 3 10% 8% 6% 6% 4 6% 8% 31%	4720
	11th to 20th	Night	12% 17% 8% 14% 6% 5% 4 3 4 5% 23%	5339
	21st to end	Night	21% 17% 7% 12% 5% 4 4 3 4 5% 19%	7150

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	62% 3 12% 15% 7%	4692
	11th to 20th	Day	54% 7% 9% 17% 13% 1	4710
	21st to end	Day	49% 5% 11% 23% 12%	5496
February	1st to 10th	Day	53% 6% 13% 17% 10% 1	1890
	11th to 20th	Day	47% 6% 12% 26% 8% 1	1895
	21st to end	Day	51% 6% 10% 21% 10% 2	1730
March	1st to 10th	Day	39% 3 12% 27% 15% 4	4580
	11th to 20th	Day	40% 5% 14% 28% 12% 2	5085
	21st to end	Day	57% 5% 9% 15% 12% 1	5908
April	1st to 10th	Day	54% 6% 10% 19% 11% 1	2520
	11th to 20th	Day	53% 5% 9% 20% 10% 2	2494
	21st to end	Day	52% 6% 12% 19% 10% 1	2562
May	1st to 10th	Day	38% 5% 9% 30% 17% 2	8250
	11th to 20th	Day	41% 6% 9% 27% 16% 1	8226
	21st to end	Day	44% 5% 9% 26% 14% 3	9061
June	1st to 10th	Day	36% 8% 13% 27% 14% 2	2940
	11th to 20th	Day	42% 7% 14% 24% 14% 1	2940
	21st to end	Day	41% 7% 15% 23% 11% 2	2940
July	1st to 10th	Day	36% 5% 18% 33% 7% 1	6292
	11th to 20th	Day	30% 5% 16% 32% 16% 1	6285
	21st to end	Day	39% 5% 14% 24% 17% 1	6728
August	1st to 10th	Day	40% 6% 14% 26% 13% 1	4403
	11th to 20th	Day	38% 5% 11% 33% 13%	4121
	21st to end	Day	37% 5% 15% 31% 12% 1	4311
September	1st to 10th	Day	37% 6% 13% 28% 15%	2400
	11th to 20th	Day	36% 7% 15% 31% 10% 1	2390
	21st to end	Day	39% 5% 12% 30% 13% 1	2150
October	1st to 10th	Day	26% 3 7% 41% 22% 1	3260
	11th to 20th	Day	40% 5% 11% 25% 17% 2	3240
	21st to end	Day	43% 3 12% 30% 11%	3293
November	1st to 10th	Day	43% 6% 13% 22% 15% 2	1852
	11th to 20th	Day	54% 5% 12% 20% 9% 1	1749
	21st to end	Day	49% 5% 16% 22% 8% 1	1680
December	1st to 10th	Day	54% 7% 14% 18% 7% 1	2690
	11th to 20th	Day	58% 5% 10% 17% 8% 1	3085
	21st to end	Day	74% 4 7% 11% 5%	4070
January	1st to 10th	Night	57% 4 12% 20% 7%	8233
	11th to 20th	Night	63% 5% 8% 11% 12%	8280
	21st to end	Night	52% 5% 11% 18% 13%	8702
February	1st to 10th	Night	55% 5% 11% 20% 9% 1	2730
	11th to 20th	Night	46% 6% 11% 27% 9% 1	2621
	21st to end	Night	49% 5% 13% 21% 10% 2	2076
March	1st to 10th	Night	41% 5% 13% 25% 11% 6%	5493
	11th to 20th	Night	42% 5% 14% 25% 12% 3	5138
	21st to end	Night	58% 4 9% 17% 11% 1	5265
April	1st to 10th	Night	51% 5% 9% 18% 15% 2	2100
	11th to 20th	Night	48% 5% 9% 21% 15% 3	2075
	21st to end	Night	46% 6% 11% 20% 15% 2	2054
May	1st to 10th	Night	38% 6% 10% 23% 22% 2	4695
	11th to 20th	Night	38% 5% 12% 21% 21% 3	4671
	21st to end	Night	46% 5% 9% 23% 14% 2	5149
June	1st to 10th	Night	34% 7% 14% 26% 17% 2	1680
	11th to 20th	Night	38% 7% 12% 23% 18% 2	1680
	21st to end	Night	33% 7% 14% 29% 13% 3	1680
July	1st to 10th	Night	37% 4 16% 30% 11% 2	3580
	11th to 20th	Night	30% 3 14% 36% 15% 1	3572
	21st to end	Night	33% 5% 17% 27% 17% 2	3832
August	1st to 10th	Night	35% 5% 13% 28% 17% 2	2716
	11th to 20th	Night	35% 5% 15% 29% 16% 1	2999
	21st to end	Night	34% 4 16% 28% 16% 2	3586
September	1st to 10th	Night	32% 6% 11% 30% 20% 1	2000
	11th to 20th	Night	31% 6% 15% 31% 15% 1	2000
	21st to end	Night	35% 5% 10% 31% 19% 1	2235
October	1st to 10th	Night	26% 4 7% 35% 26% 3	3920
	11th to 20th	Night	31% 5% 11% 30% 22% 1	3899
	21st to end	Night	46% 4 9% 25% 14% 1	4497
November	1st to 10th	Night	43% 5% 12% 25% 13% 2	2666
	11th to 20th	Night	52% 6% 13% 18% 9% 2	2867
	21st to end	Night	52% 4 13% 23% 7% 1	2940
December	1st to 10th	Night	50% 7% 17% 22% 5%	4720
	11th to 20th	Night	64% 5% 9% 14% 7% 1	5341
	21st to end	Night	68% 5% 7% 13% 6%	7150

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	18% 15% 35% 22% 8% 2	330
	11th to 20th	Day	22% 17% 41% 17% 3 1	330
	21st to end	Day	20% 20% 35% 20% 4	363
February	1st to 10th	Day	18% 19% 43% 15% 4 2	330
	11th to 20th	Day	18% 24% 36% 18% 4 1	330
	21st to end	Day	21% 19% 44% 15% 1	273
March	1st to 10th	Day	20% 22% 36% 17% 5%	330
	11th to 20th	Day	25% 15% 36% 16% 5% 2	330
	21st to end	Day	26% 17% 32% 16% 8% 1	505
April	1st to 10th	Day	28% 17% 34% 17% 4	540
	11th to 20th	Day	29% 17% 29% 16% 9% 1	532
	21st to end	Day	24% 18% 29% 21% 7% 1	551
May	1st to 10th	Day	21% 16% 29% 25% 7% 2	753
	11th to 20th	Day	20% 15% 28% 24% 11% 3	775
	21st to end	Day	19% 10% 28% 26% 13% 3	844
June	1st to 10th	Day	11% 9% 33% 27% 17% 3	780
	11th to 20th	Day	17% 9% 35% 26% 12% 1	780
	21st to end	Day	18% 7% 33% 26% 12% 4	780
July	1st to 10th	Day	8% 5% 22% 32% 23% 9%	722
	11th to 20th	Day	10% 7% 27% 32% 18% 7%	718
	21st to end	Day	8% 5% 26% 34% 20% 7%	794
August	1st to 10th	Day	9% 6% 24% 31% 22% 8%	726
	11th to 20th	Day	15% 6% 22% 27% 23% 7%	665
	21st to end	Day	13% 7% 24% 30% 20% 6%	583
September	1st to 10th	Day	16% 8% 25% 28% 16% 7%	530
	11th to 20th	Day	12% 6% 25% 33% 20% 4	530
	21st to end	Day	16% 12% 25% 28% 15% 4	480
October	1st to 10th	Day	15% 13% 35% 22% 13% 2	330
	11th to 20th	Day	24% 20% 33% 16% 6%	330
	21st to end	Day	25% 16% 35% 17% 6% 1	363
November	1st to 10th	Day	19% 17% 37% 21% 5% 2	330
	11th to 20th	Day	22% 20% 35% 20% 2 1	330
	21st to end	Day	22% 17% 42% 13% 6%	330
December	1st to 10th	Day	17% 20% 36% 22% 5%	330
	11th to 20th	Day	20% 20% 37% 16% 5% 1	330
	21st to end	Day	27% 18% 37% 15% 2	363
January	1st to 10th	Night	15% 15% 36% 26% 7% 1	1050
	11th to 20th	Night	18% 16% 35% 26% 4 1	1050
	21st to end	Night	18% 13% 36% 26% 7%	1155
February	1st to 10th	Night	16% 14% 38% 25% 6%	1050
	11th to 20th	Night	14% 16% 41% 23% 6%	986
	21st to end	Night	20% 16% 37% 23% 3	692
March	1st to 10th	Night	18% 14% 36% 25% 6%	840
	11th to 20th	Night	21% 13% 32% 26% 8%	652
	21st to end	Night	22% 12% 31% 25% 8% 1	693
April	1st to 10th	Night	25% 12% 36% 22% 5%	630
	11th to 20th	Night	25% 12% 31% 26% 5%	623
	21st to end	Night	21% 10% 33% 28% 7%	630
May	1st to 10th	Night	21% 9% 34% 31% 6%	630
	11th to 20th	Night	16% 10% 31% 33% 8% 1	621
	21st to end	Night	16% 5% 30% 35% 14%	683
June	1st to 10th	Night	11% 8% 31% 40% 10%	630
	11th to 20th	Night	13% 7% 32% 38% 10%	630
	21st to end	Night	11% 5% 25% 42% 16% 1	630
July	1st to 10th	Night	8% 3 18% 42% 27% 2	585
	11th to 20th	Night	10% 4 22% 38% 23% 3	582
	21st to end	Night	6% 3 18% 50% 21% 3	657
August	1st to 10th	Night	9% 2 20% 45% 24% 1	597
	11th to 20th	Night	12% 3 17% 39% 26% 4	594
	21st to end	Night	11% 5% 21% 40% 21% 2	660
September	1st to 10th	Night	13% 4 25% 36% 18% 4	600
	11th to 20th	Night	13% 4 26% 32% 22% 3	600
	21st to end	Night	15% 10% 25% 34% 15% 1	790
October	1st to 10th	Night	15% 9% 29% 31% 15% 1	800
	11th to 20th	Night	20% 13% 33% 27% 7%	800
	21st to end	Night	22% 10% 32% 28% 8%	880
November	1st to 10th	Night	19% 10% 36% 27% 7% 1	820
	11th to 20th	Night	18% 16% 39% 22% 5%	977
	21st to end	Night	20% 15% 37% 22% 6%	1050
December	1st to 10th	Night	18% 14% 39% 24% 5%	1050
	11th to 20th	Night	22% 15% 35% 22% 5% 1	1050
	21st to end	Night	27% 12% 33% 22% 5% 1	1155

Page generated at 2026-06-28 01:10:46. Version ac07

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