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 2025-02-25.

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% 4 4 5% 7% 36%	108845
	Night	12% 10% 4 9% 5% 4 4 4 5% 6% 36%	110031
Transparency	Day	45% 6% 12% 24% 12% 1	112376
	Night	46% 6% 11% 23% 13% 1	114640
Seeing	Day	17% 12% 31% 24% 12% 3	16309
	Night	17% 11% 32% 29% 10% 1	26368

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	6% 12% 6% 18% 9% 6% 4 3 4 5% 27%	3617
	11th to 20th	Day	7% 11% 7% 11% 5% 5% 7% 7% 9% 7% 23%	3620
	21st to end	Day	10% 14% 7% 11% 4 4 3 3 4 6% 33%	4240
February	1st to 10th	Day	9% 13% 5% 10% 6% 5% 6% 5% 6% 5% 31%	1800
	11th to 20th	Day	9% 12% 4 8% 6% 5% 5% 4 6% 6% 35%	1794
	21st to end	Day	11% 12% 4 9% 7% 5% 5% 3 5% 7% 31%	1610
March	1st to 10th	Day	14% 10% 3 5% 4 3 3 3 3 5% 48%	3120
	11th to 20th	Day	10% 7% 4 11% 4 4 4 4 4 8% 41%	3475
	21st to end	Day	21% 14% 4 9% 4 4 4 4 4 6% 27%	4032
April	1st to 10th	Day	17% 12% 4 8% 5% 5% 4 3 4 6% 31%	2280
	11th to 20th	Day	20% 11% 3 9% 4 4 4 4 4 5% 33%	2254
	21st to end	Day	20% 12% 2 8% 4 4 4 4 5% 6% 31%	2317
May	1st to 10th	Day	17% 7% 2 6% 5% 5% 4 4 6% 6% 38%	4399
	11th to 20th	Day	14% 7% 2 6% 5% 4 5% 4 6% 8% 41%	4399
	21st to end	Day	16% 7% 3 7% 5% 4 5% 4 6% 6% 37%	4824
June	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 7% 9% 43%	2660
	11th to 20th	Day	13% 6% 2 7% 5% 5% 4 3 6% 8% 39%	2660
	21st to end	Day	12% 7% 3 6% 5% 5% 5% 4 7% 8% 38%	2660
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 5% 8% 10% 37%	4440
	11th to 20th	Day	5% 3 1 5% 4 4 6% 5% 7% 12% 49%	4440
	21st to end	Day	8% 7% 3 7% 6% 6% 4 4 7% 7% 43%	4813
August	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 5% 6% 8% 39%	4282
	11th to 20th	Day	13% 6% 2 6% 3 5% 5% 4 5% 8% 45%	3955
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 3 6% 9% 42%	4180
September	1st to 10th	Day	13% 6% 3 5% 3 4 4 4 6% 8% 44%	2280
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 5% 8% 45%	2271
	21st to end	Day	12% 7% 3 7% 4 3 3 4 6% 7% 42%	2043
October	1st to 10th	Day	14% 7% 2 6% 4 5% 4 3 5% 6% 44%	1900
	11th to 20th	Day	16% 12% 2 7% 4 4 4 5% 5% 8% 35%	1900
	21st to end	Day	17% 12% 3 8% 4 3 4 2 4 6% 38%	1952
November	1st to 10th	Day	13% 10% 3 7% 4 5% 5% 3 4 7% 40%	1762
	11th to 20th	Day	14% 13% 5% 9% 6% 4 4 3 5% 8% 29%	1666
	21st to end	Day	12% 12% 3 8% 6% 4 4 3 4 5% 39%	1600
December	1st to 10th	Day	7% 8% 4 13% 7% 8% 6% 5% 6% 6% 29%	2610
	11th to 20th	Day	13% 16% 5% 10% 7% 5% 5% 4 4 6% 26%	3008
	21st to end	Day	19% 21% 8% 13% 6% 4 4 3 4 4 15%	3982
January	1st to 10th	Night	7% 11% 6% 15% 8% 4 4 3 4 5% 32%	6348
	11th to 20th	Night	8% 12% 6% 15% 7% 6% 8% 6% 8% 5% 19%	6360
	21st to end	Night	10% 16% 7% 11% 5% 5% 4 3 5% 5% 28%	6722
February	1st to 10th	Night	8% 13% 5% 12% 6% 5% 6% 3 5% 5% 32%	2600
	11th to 20th	Night	9% 9% 4 9% 5% 5% 5% 4 5% 7% 38%	2492
	21st to end	Night	14% 11% 3 9% 7% 4 4 4 6% 6% 33%	1939
March	1st to 10th	Night	11% 8% 2 6% 4 4 5% 4 5% 7% 43%	3733
	11th to 20th	Night	10% 9% 2 8% 5% 6% 5% 4 5% 6% 40%	3513
	21st to end	Night	24% 11% 4 11% 4 4 3 2 3 5% 29%	3599
April	1st to 10th	Night	18% 11% 3 7% 5% 4 4 3 5% 6% 34%	1900
	11th to 20th	Night	19% 10% 3 8% 3 3 3 3 5% 5% 37%	1875
	21st to end	Night	16% 10% 3 7% 4 4 4 3 4 8% 36%	1859
May	1st to 10th	Night	15% 9% 3 7% 5% 5% 5% 4 5% 8% 34%	2506
	11th to 20th	Night	11% 5% 2 6% 4 4 4 4 6% 6% 48%	2506
	21st to end	Night	11% 9% 3 7% 4 4 4 4 5% 8% 42%	2743
June	1st to 10th	Night	10% 4 3 6% 4 5% 4 4 7% 7% 48%	1520
	11th to 20th	Night	12% 6% 3 8% 4 3 5% 3 6% 8% 43%	1520
	21st to end	Night	9% 5% 2 6% 5% 4 4 4 7% 9% 47%	1520
July	1st to 10th	Night	12% 5% 3 6% 3 4 4 3 5% 9% 45%	2530
	11th to 20th	Night	4 3 2 5% 4 5% 5% 4 5% 7% 56%	2530
	21st to end	Night	5% 5% 2 6% 4 6% 5% 5% 7% 7% 49%	2750
August	1st to 10th	Night	10% 6% 2 7% 4 5% 4 4 6% 7% 46%	2641
	11th to 20th	Night	10% 6% 2 6% 4 4 4 4 5% 7% 49%	2879
	21st to end	Night	10% 6% 2 6% 4 4 4 3 6% 7% 49%	3476
September	1st to 10th	Night	9% 5% 3 7% 3 3 4 3 5% 6% 51%	1900
	11th to 20th	Night	11% 5% 1 5% 3 3 4 3 5% 8% 52%	1900
	21st to end	Night	13% 7% 2 5% 4 3 4 3 5% 5% 50%	2123
October	1st to 10th	Night	13% 6% 3 5% 3 3 4 3 5% 6% 50%	2280
	11th to 20th	Night	15% 8% 3 6% 4 4 4 4 5% 8% 40%	2280
	21st to end	Night	17% 10% 3 7% 5% 4 4 4 5% 6% 35%	2646
November	1st to 10th	Night	14% 9% 3 6% 4 4 3 3 5% 6% 41%	2536
	11th to 20th	Night	12% 13% 4 11% 6% 4 5% 3 4 6% 32%	2730
	21st to end	Night	14% 12% 4 10% 5% 4 3 3 4 5% 35%	2800
December	1st to 10th	Night	8% 9% 3 10% 8% 6% 6% 4 6% 8% 32%	4580
	11th to 20th	Night	12% 17% 8% 15% 6% 4 4 3 4 5% 23%	5199
	21st to end	Night	21% 17% 7% 12% 5% 4 4 3 4 5% 18%	6996

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	61% 4 11% 17% 7%	3618
	11th to 20th	Day	54% 7% 9% 15% 14% 1	3620
	21st to end	Day	53% 5% 14% 18% 11%	4240
February	1st to 10th	Day	53% 6% 13% 17% 10% 1	1800
	11th to 20th	Day	47% 6% 12% 25% 8% 1	1803
	21st to end	Day	51% 6% 10% 20% 10% 2	1610
March	1st to 10th	Day	40% 4 10% 25% 18% 2	3120
	11th to 20th	Day	40% 6% 11% 31% 11% 1	3475
	21st to end	Day	58% 6% 9% 18% 8% 1	4032
April	1st to 10th	Day	53% 6% 10% 19% 11% 1	2280
	11th to 20th	Day	52% 5% 9% 21% 11% 2	2254
	21st to end	Day	52% 6% 12% 18% 10% 1	2317
May	1st to 10th	Day	43% 7% 11% 24% 14%	4440
	11th to 20th	Day	38% 8% 11% 31% 11% 1	4403
	21st to end	Day	45% 8% 10% 21% 15% 2	4837
June	1st to 10th	Day	35% 8% 14% 26% 15% 2	2660
	11th to 20th	Day	40% 7% 14% 24% 15% 1	2660
	21st to end	Day	40% 8% 15% 24% 12% 2	2660
July	1st to 10th	Day	41% 6% 18% 25% 8% 1	4371
	11th to 20th	Day	27% 6% 17% 31% 18% 1	4365
	21st to end	Day	38% 6% 14% 23% 18% 1	4662
August	1st to 10th	Day	40% 6% 14% 26% 13% 1	4267
	11th to 20th	Day	38% 5% 11% 33% 13%	3994
	21st to end	Day	38% 5% 15% 30% 12% 1	4179
September	1st to 10th	Day	37% 6% 12% 28% 16%	2280
	11th to 20th	Day	36% 7% 14% 31% 10% 1	2271
	21st to end	Day	39% 6% 12% 29% 13% 1	2043
October	1st to 10th	Day	26% 4 7% 41% 22%	3160
	11th to 20th	Day	39% 5% 11% 26% 17% 2	3140
	21st to end	Day	43% 3 12% 30% 11%	3190
November	1st to 10th	Day	43% 6% 13% 21% 15% 2	1762
	11th to 20th	Day	55% 5% 13% 18% 9% 1	1666
	21st to end	Day	48% 5% 16% 22% 8% 1	1600
December	1st to 10th	Day	53% 7% 15% 19% 6% 1	2610
	11th to 20th	Day	59% 5% 10% 17% 8% 1	3005
	21st to end	Day	74% 4 7% 11% 5%	3982
January	1st to 10th	Night	55% 5% 10% 21% 9% 1	6348
	11th to 20th	Night	61% 6% 9% 11% 13%	6360
	21st to end	Night	55% 6% 11% 16% 11%	6722
February	1st to 10th	Night	55% 5% 11% 19% 9% 1	2600
	11th to 20th	Night	46% 6% 11% 26% 9% 1	2493
	21st to end	Night	50% 5% 13% 20% 10% 2	1939
March	1st to 10th	Night	39% 7% 11% 29% 10% 4	3733
	11th to 20th	Night	40% 6% 10% 27% 14% 2	3513
	21st to end	Night	58% 6% 7% 20% 8% 1	3599
April	1st to 10th	Night	51% 5% 9% 19% 15% 2	1900
	11th to 20th	Night	47% 6% 8% 21% 15% 3	1875
	21st to end	Night	46% 7% 12% 20% 15% 2	1859
May	1st to 10th	Night	45% 8% 14% 15% 17% 1	2530
	11th to 20th	Night	34% 8% 11% 25% 20% 3	2507
	21st to end	Night	38% 7% 12% 24% 18% 1	2751
June	1st to 10th	Night	33% 7% 15% 26% 16% 2	1520
	11th to 20th	Night	37% 8% 11% 24% 18% 2	1520
	21st to end	Night	32% 8% 13% 30% 13% 3	1520
July	1st to 10th	Night	38% 4 18% 26% 12% 2	2490
	11th to 20th	Night	26% 4 15% 36% 17% 1	2482
	21st to end	Night	32% 6% 16% 25% 19% 2	2662
August	1st to 10th	Night	36% 5% 12% 28% 17% 2	2632
	11th to 20th	Night	34% 5% 14% 29% 16% 1	2906
	21st to end	Night	35% 4 16% 27% 16% 2	3476
September	1st to 10th	Night	32% 6% 11% 29% 21% 1	1900
	11th to 20th	Night	30% 6% 15% 32% 16% 1	1900
	21st to end	Night	35% 5% 10% 31% 18% 1	2123
October	1st to 10th	Night	26% 4 7% 35% 26% 3	3800
	11th to 20th	Night	31% 5% 11% 31% 22% 1	3779
	21st to end	Night	46% 5% 10% 25% 14% 1	4358
November	1st to 10th	Night	43% 5% 12% 24% 14% 2	2536
	11th to 20th	Night	53% 6% 13% 18% 10% 1	2730
	21st to end	Night	52% 5% 14% 22% 7% 1	2800
December	1st to 10th	Night	49% 7% 18% 22% 4	4580
	11th to 20th	Night	64% 5% 9% 14% 7% 1	5201
	21st to end	Night	69% 5% 7% 13% 6%	6996

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% 33% 23% 9% 2	300
	11th to 20th	Day	22% 16% 40% 18% 3 1	300
	21st to end	Day	21% 19% 36% 20% 4	330
February	1st to 10th	Day	18% 20% 42% 15% 4 1	300
	11th to 20th	Day	17% 24% 36% 18% 4 1	300
	21st to end	Day	19% 19% 44% 16% 1	237
March	1st to 10th	Day	19% 22% 37% 17% 5%	270
	11th to 20th	Day	24% 16% 33% 19% 6% 3	270
	21st to end	Day	26% 17% 32% 16% 9% 1	425
April	1st to 10th	Day	27% 17% 33% 19% 4	460
	11th to 20th	Day	29% 16% 29% 17% 9% 1	452
	21st to end	Day	24% 18% 28% 21% 8% 2	469
May	1st to 10th	Day	21% 16% 30% 24% 7% 1	653
	11th to 20th	Day	20% 14% 29% 24% 11% 3	675
	21st to end	Day	19% 11% 27% 25% 14% 3	734
June	1st to 10th	Day	11% 9% 33% 27% 17% 3	680
	11th to 20th	Day	15% 8% 35% 28% 13% 2	680
	21st to end	Day	16% 7% 32% 26% 13% 5%	680
July	1st to 10th	Day	8% 6% 23% 31% 23% 10%	671
	11th to 20th	Day	9% 6% 26% 32% 19% 7%	668
	21st to end	Day	8% 5% 26% 34% 20% 7%	739
August	1st to 10th	Day	9% 6% 24% 32% 22% 7%	676
	11th to 20th	Day	15% 5% 22% 26% 24% 8%	618
	21st to end	Day	13% 7% 24% 30% 20% 6%	539
September	1st to 10th	Day	17% 7% 25% 29% 17% 6%	490
	11th to 20th	Day	12% 6% 26% 31% 20% 4	490
	21st to end	Day	17% 13% 26% 27% 14% 2	443
October	1st to 10th	Day	16% 14% 33% 22% 14% 1	300
	11th to 20th	Day	23% 20% 34% 17% 6%	300
	21st to end	Day	25% 17% 35% 17% 5% 1	330
November	1st to 10th	Day	19% 14% 37% 22% 5% 2	300
	11th to 20th	Day	21% 20% 37% 19% 3 1	300
	21st to end	Day	21% 16% 43% 12% 7%	300
December	1st to 10th	Day	15% 21% 36% 22% 6%	300
	11th to 20th	Day	21% 20% 36% 17% 6% 1	300
	21st to end	Day	27% 18% 35% 16% 3	330
January	1st to 10th	Night	14% 16% 36% 26% 8% 1	1000
	11th to 20th	Night	18% 15% 35% 26% 4 1	1000
	21st to end	Night	19% 13% 36% 25% 7%	1100
February	1st to 10th	Night	17% 14% 38% 25% 6%	1000
	11th to 20th	Night	14% 16% 41% 23% 6%	938
	21st to end	Night	20% 16% 37% 23% 3	647
March	1st to 10th	Night	19% 13% 36% 26% 6%	760
	11th to 20th	Night	19% 13% 32% 28% 8%	590
	21st to end	Night	22% 12% 29% 26% 9% 2	627
April	1st to 10th	Night	25% 12% 37% 22% 5%	570
	11th to 20th	Night	25% 12% 32% 27% 5%	563
	21st to end	Night	21% 11% 33% 27% 8% 1	570
May	1st to 10th	Night	22% 9% 34% 30% 5%	570
	11th to 20th	Night	17% 9% 30% 35% 7% 1	561
	21st to end	Night	15% 5% 30% 34% 15%	617
June	1st to 10th	Night	10% 8% 32% 40% 10%	570
	11th to 20th	Night	13% 6% 30% 39% 11%	570
	21st to end	Night	11% 5% 25% 42% 16% 1	570
July	1st to 10th	Night	8% 3 19% 41% 27% 2	555
	11th to 20th	Night	9% 5% 23% 37% 24% 3	552
	21st to end	Night	6% 2 19% 49% 22% 3	624
August	1st to 10th	Night	8% 2 21% 45% 23% 1	567
	11th to 20th	Night	12% 3 17% 39% 27% 3	564
	21st to end	Night	11% 4 21% 40% 21% 2	627
September	1st to 10th	Night	13% 4 24% 38% 17% 4	570
	11th to 20th	Night	13% 4 27% 32% 21% 3	570
	21st to end	Night	15% 10% 27% 33% 14% 1	750
October	1st to 10th	Night	15% 9% 29% 30% 16% 1	760
	11th to 20th	Night	20% 13% 33% 27% 7%	760
	21st to end	Night	22% 11% 32% 28% 7%	836
November	1st to 10th	Night	19% 10% 36% 27% 7% 1	780
	11th to 20th	Night	18% 16% 39% 22% 5%	930
	21st to end	Night	21% 14% 37% 22% 6%	1000
December	1st to 10th	Night	18% 13% 39% 25% 5% 1	1000
	11th to 20th	Night	21% 14% 36% 22% 6% 1	1000
	21st to end	Night	27% 13% 33% 22% 5% 1	1100

Page generated at 2025-02-22 05:51:39. Version ac07

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