N5PA Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the N5PA Observatory clear sky chart from 2005-11-06 to 2026-02-01.

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	11% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	127044
	Night	12% 6% 2 6% 4 4 4 4 6% 7% 44%	124909
Transparency	Day	39% 5% 11% 20% 18% 7%	130795
	Night	38% 5% 11% 19% 19% 9%	129232
Seeing	Day	15% 8% 21% 24% 21% 10%	16357
	Night	15% 7% 22% 29% 22% 5%	25956

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	16% 6% 5% 6% 2 3 3 4 4 5% 46%	4257
	11th to 20th	Day	11% 6% 3 6% 3 3 4 3 4 5% 52%	4420
	21st to end	Day	22% 10% 3 7% 4 3 2 2 4 5% 38%	5082
February	1st to 10th	Day	17% 9% 2 7% 5% 4 5% 3 5% 5% 39%	2000
	11th to 20th	Day	19% 7% 2 5% 4 4 3 3 4 6% 42%	1948
	21st to end	Day	16% 9% 3 7% 5% 4 3 3 4 6% 40%	1650
March	1st to 10th	Day	19% 9% 3 7% 5% 4 4 4 5% 6% 35%	4480
	11th to 20th	Day	13% 5% 2 6% 4 4 4 4 5% 7% 45%	4928
	21st to end	Day	16% 7% 3 8% 5% 5% 4 3 4 5% 40%	5872
April	1st to 10th	Day	12% 7% 2 6% 5% 4 5% 5% 6% 7% 42%	2400
	11th to 20th	Day	14% 6% 2 6% 5% 4 4 4 5% 6% 43%	2374
	21st to end	Day	8% 5% 2 5% 4 5% 4 5% 6% 8% 48%	2400
May	1st to 10th	Day	15% 7% 2 7% 5% 5% 5% 4 6% 8% 35%	5405
	11th to 20th	Day	10% 5% 2 7% 4 5% 5% 4 7% 9% 41%	5404
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 4 7% 10% 43%	6433
June	1st to 10th	Day	9% 6% 2 6% 5% 6% 6% 6% 8% 11% 35%	2600
	11th to 20th	Day	4 5% 2 6% 6% 7% 7% 6% 8% 9% 40%	2710
	21st to end	Day	5% 5% 3 6% 7% 8% 9% 6% 9% 10% 31%	2800
July	1st to 10th	Day	5% 5% 2 8% 7% 8% 8% 7% 10% 12% 30%	6052
	11th to 20th	Day	5% 4 2 7% 6% 6% 8% 7% 10% 12% 33%	5679
	21st to end	Day	6% 6% 3 9% 7% 7% 8% 6% 9% 13% 26%	5922
August	1st to 10th	Day	2 3 2 5% 4 4 4 4 7% 9% 56%	3905
	11th to 20th	Day	5% 4 2 6% 5% 6% 6% 5% 7% 10% 45%	3849
	21st to end	Day	7% 5% 2 8% 5% 6% 6% 5% 7% 9% 40%	4312
September	1st to 10th	Day	9% 7% 2 7% 6% 6% 6% 4 7% 8% 39%	2400
	11th to 20th	Day	11% 7% 2 5% 4 5% 5% 5% 6% 7% 42%	2285
	21st to end	Day	9% 4 2 5% 4 4 3 3 6% 7% 53%	2200
October	1st to 10th	Day	6% 5% 2 5% 3 4 4 4 5% 7% 56%	2200
	11th to 20th	Day	9% 5% 2 4 4 3 3 3 5% 5% 57%	2005
	21st to end	Day	11% 4 2 6% 3 3 3 2 4 6% 56%	2200
November	1st to 10th	Day	11% 6% 2 5% 3 4 3 3 4 5% 54%	1976
	11th to 20th	Day	12% 5% 2 4 4 3 3 4 4 5% 54%	1890
	21st to end	Day	13% 6% 2 5% 3 5% 4 3 5% 6% 47%	1890
December	1st to 10th	Day	16% 8% 2 6% 4 4 3 3 4 6% 44%	3020
	11th to 20th	Day	10% 9% 3 7% 5% 4 4 3 4 5% 45%	3463
	21st to end	Day	17% 7% 2 5% 4 3 3 3 4 6% 45%	4633
January	1st to 10th	Night	18% 7% 4 6% 3 3 3 2 3 4 48%	5878
	11th to 20th	Night	16% 6% 4 5% 3 3 3 3 3 5% 48%	5726
	21st to end	Night	24% 9% 2 5% 3 3 3 2 4 4 40%	6116
February	1st to 10th	Night	16% 8% 2 6% 4 4 4 4 6% 6% 41%	2401
	11th to 20th	Night	20% 9% 4 6% 4 2 3 2 4 6% 41%	2338
	21st to end	Night	18% 8% 3 6% 5% 3 4 3 4 5% 41%	1980
March	1st to 10th	Night	19% 10% 3 7% 4 3 3 3 5% 6% 37%	5373
	11th to 20th	Night	12% 6% 2 6% 4 3 4 4 5% 6% 47%	5072
	21st to end	Night	15% 6% 3 6% 4 4 3 3 5% 6% 45%	5054
April	1st to 10th	Night	14% 7% 3 5% 4 4 4 3 5% 6% 45%	2000
	11th to 20th	Night	12% 5% 2 5% 5% 4 4 3 5% 7% 48%	1975
	21st to end	Night	8% 5% 2 5% 4 4 4 3 6% 7% 55%	2000
May	1st to 10th	Night	14% 6% 3 7% 4 5% 4 3 6% 8% 39%	4490
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 4 6% 9% 41%	4471
	21st to end	Night	7% 5% 2 7% 5% 5% 6% 5% 7% 12% 39%	4421
June	1st to 10th	Night	8% 6% 3 8% 5% 5% 5% 5% 6% 10% 40%	1800
	11th to 20th	Night	4 4 1 6% 6% 5% 6% 5% 8% 11% 44%	1680
	21st to end	Night	6% 5% 3 7% 4 6% 4 5% 9% 12% 40%	1600
July	1st to 10th	Night	4 6% 2 8% 6% 6% 7% 5% 9% 12% 34%	3892
	11th to 20th	Night	6% 5% 2 7% 6% 6% 8% 6% 10% 12% 32%	4270
	21st to end	Night	5% 6% 3 9% 7% 7% 8% 6% 9% 12% 28%	4929
August	1st to 10th	Night	2 3 1 3 3 4 5% 4 7% 12% 55%	3244
	11th to 20th	Night	5% 3 2 6% 5% 4 6% 5% 10% 12% 43%	3200
	21st to end	Night	5% 5% 2 8% 6% 6% 5% 5% 7% 9% 42%	3586
September	1st to 10th	Night	9% 6% 2 6% 5% 5% 7% 5% 7% 8% 39%	2000
	11th to 20th	Night	9% 6% 2 7% 5% 4 4 4 6% 8% 44%	2092
	21st to end	Night	8% 5% 2 6% 4 3 4 4 5% 7% 53%	2200
October	1st to 10th	Night	8% 5% 2 5% 4 3 4 4 5% 6% 55%	2200
	11th to 20th	Night	8% 4 2 4 4 4 3 3 4 5% 60%	2390
	21st to end	Night	13% 5% 3 4 3 2 3 3 3 4 57%	2640
November	1st to 10th	Night	10% 5% 2 5% 3 3 3 2 4 5% 59%	2539
	11th to 20th	Night	13% 6% 2 4 2 3 2 3 4 5% 57%	2730
	21st to end	Night	13% 6% 2 5% 4 4 4 4 5% 6% 48%	2730
December	1st to 10th	Night	18% 7% 2 5% 3 4 4 3 5% 5% 45%	4380
	11th to 20th	Night	14% 9% 2 6% 4 3 4 4 4 5% 45%	4952
	21st to end	Night	19% 8% 2 6% 3 3 2 2 4 5% 47%	6560

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	42% 3 3 24% 25% 4	4258
	11th to 20th	Day	35% 3 3 18% 33% 7%	4420
	21st to end	Day	51% 2 5% 12% 17% 13%	5082
February	1st to 10th	Day	47% 3 6% 15% 19% 10%	2000
	11th to 20th	Day	43% 4 5% 17% 23% 8%	1958
	21st to end	Day	46% 3 6% 17% 16% 11%	1650
March	1st to 10th	Day	50% 3 7% 14% 19% 7%	4480
	11th to 20th	Day	38% 3 6% 17% 19% 18%	4928
	21st to end	Day	47% 4 8% 14% 19% 8%	5874
April	1st to 10th	Day	41% 5% 8% 18% 19% 9%	2400
	11th to 20th	Day	41% 4 6% 17% 22% 9%	2374
	21st to end	Day	33% 5% 10% 24% 23% 5%	2400
May	1st to 10th	Day	45% 4 11% 24% 13% 2	5440
	11th to 20th	Day	39% 5% 16% 22% 17% 2	5408
	21st to end	Day	35% 5% 15% 29% 14% 2	6447
June	1st to 10th	Day	40% 7% 15% 24% 12% 2	2600
	11th to 20th	Day	35% 8% 18% 22% 14% 3	2710
	21st to end	Day	42% 9% 17% 20% 10% 1	2800
July	1st to 10th	Day	42% 10% 23% 19% 6% 1	5988
	11th to 20th	Day	38% 10% 31% 19% 2	5610
	21st to end	Day	45% 11% 19% 22% 3 1	5752
August	1st to 10th	Day	23% 6% 14% 29% 25% 2	3893
	11th to 20th	Day	33% 7% 17% 27% 14% 1	3885
	21st to end	Day	39% 8% 16% 17% 16% 3	4311
September	1st to 10th	Day	41% 7% 16% 16% 14% 6%	2400
	11th to 20th	Day	39% 7% 11% 18% 17% 7%	2285
	21st to end	Day	30% 6% 10% 24% 19% 10%	2200
October	1st to 10th	Day	24% 3 6% 14% 25% 28%	3590
	11th to 20th	Day	19% 3 4 15% 29% 31%	3245
	21st to end	Day	23% 3 3 15% 36% 20%	3538
November	1st to 10th	Day	32% 3 7% 18% 27% 13%	1976
	11th to 20th	Day	33% 3 7% 16% 28% 15%	1890
	21st to end	Day	38% 3 7% 18% 22% 11%	1890
December	1st to 10th	Day	42% 2 7% 18% 25% 6%	3020
	11th to 20th	Day	42% 3 9% 16% 22% 10%	3460
	21st to end	Day	42% 3 4 23% 25% 3	4633
January	1st to 10th	Night	42% 2 4 20% 26% 6%	5878
	11th to 20th	Night	40% 3 4 17% 27% 10%	5726
	21st to end	Night	50% 2 3 13% 22% 9%	6116
February	1st to 10th	Night	43% 3 7% 17% 21% 10%	2401
	11th to 20th	Night	46% 3 5% 14% 21% 11%	2339
	21st to end	Night	46% 3 8% 16% 14% 13%	1980
March	1st to 10th	Night	48% 3 7% 14% 20% 8%	5373
	11th to 20th	Night	38% 3 7% 17% 20% 16%	5072
	21st to end	Night	41% 3 11% 19% 17% 9%	5054
April	1st to 10th	Night	40% 5% 9% 16% 18% 11%	2000
	11th to 20th	Night	37% 4 9% 19% 22% 9%	1975
	21st to end	Night	29% 4 10% 23% 27% 7%	2000
May	1st to 10th	Night	43% 5% 13% 20% 16% 3	4520
	11th to 20th	Night	40% 5% 17% 24% 14% 1	4472
	21st to end	Night	35% 6% 18% 25% 14% 2	4429
June	1st to 10th	Night	37% 8% 15% 25% 12% 3	1800
	11th to 20th	Night	31% 8% 20% 27% 13% 3	1680
	21st to end	Night	34% 8% 19% 26% 10% 3	1600
July	1st to 10th	Night	40% 10% 25% 18% 6% 1	3849
	11th to 20th	Night	40% 12% 31% 14% 2 1	4219
	21st to end	Night	45% 13% 16% 23% 3 1	4785
August	1st to 10th	Night	20% 8% 20% 29% 23% 1	3232
	11th to 20th	Night	29% 10% 20% 27% 12% 1	3230
	21st to end	Night	38% 9% 16% 20% 14% 4	3586
September	1st to 10th	Night	40% 8% 17% 15% 14% 6%	2000
	11th to 20th	Night	36% 6% 15% 19% 16% 8%	2092
	21st to end	Night	30% 5% 10% 25% 20% 10%	2200
October	1st to 10th	Night	27% 4 7% 11% 24% 27%	3590
	11th to 20th	Night	19% 3 4 19% 22% 34%	3889
	21st to end	Night	22% 2 3 14% 36% 23%	4252
November	1st to 10th	Night	30% 2 7% 19% 27% 15%	2539
	11th to 20th	Night	31% 3 6% 17% 28% 15%	2730
	21st to end	Night	36% 4 6% 21% 19% 13%	2730
December	1st to 10th	Night	41% 2 6% 18% 25% 7%	4380
	11th to 20th	Night	41% 3 7% 17% 25% 7%	4954
	21st to end	Night	42% 2 5% 19% 28% 4	6560

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	27% 21% 33% 15% 3 1	330
	11th to 20th	Day	22% 21% 33% 17% 7% 1	330
	21st to end	Day	28% 21% 32% 17% 2	363
February	1st to 10th	Day	26% 19% 32% 15% 7%	300
	11th to 20th	Day	34% 18% 29% 15% 4	300
	21st to end	Day	22% 21% 43% 12% 2	249
March	1st to 10th	Day	25% 18% 37% 16% 4	300
	11th to 20th	Day	26% 19% 33% 18% 3 1	300
	21st to end	Day	22% 15% 33% 23% 7%	507
April	1st to 10th	Day	16% 17% 33% 21% 11% 1	500
	11th to 20th	Day	21% 15% 29% 21% 11% 2	492
	21st to end	Day	14% 10% 27% 28% 18% 3	500
May	1st to 10th	Day	16% 10% 25% 23% 22% 4	503
	11th to 20th	Day	11% 5% 27% 28% 19% 10%	527
	21st to end	Day	8% 4 19% 33% 24% 12%	573
June	1st to 10th	Day	12% 3 17% 31% 25% 11%	530
	11th to 20th	Day	6% 3 12% 32% 33% 15%	640
	21st to end	Day	7% 2 12% 29% 32% 18%	730
July	1st to 10th	Day	7% 2 8% 28% 35% 20%	721
	11th to 20th	Day	8% 2 5% 19% 38% 29%	627
	21st to end	Day	8% 1 7% 24% 36% 24%	576
August	1st to 10th	Day	5% 1 9% 23% 33% 28%	526
	11th to 20th	Day	10% 1 6% 17% 39% 27%	519
	21st to end	Day	15% 2 8% 22% 30% 25%	583
September	1st to 10th	Day	11% 1 11% 28% 34% 16%	530
	11th to 20th	Day	14% 4 10% 23% 33% 17%	530
	21st to end	Day	12% 4 13% 29% 30% 12%	530
October	1st to 10th	Day	8% 7% 21% 35% 23% 7%	530
	11th to 20th	Day	10% 6% 23% 31% 25% 4	335
	21st to end	Day	18% 10% 19% 30% 17% 5%	363
November	1st to 10th	Day	18% 8% 27% 32% 11% 4	330
	11th to 20th	Day	18% 11% 31% 26% 12% 1	330
	21st to end	Day	16% 18% 34% 18% 10% 3	330
December	1st to 10th	Day	24% 14% 35% 19% 7% 1	330
	11th to 20th	Day	23% 15% 36% 19% 6% 1	330
	21st to end	Day	27% 15% 29% 21% 7% 1	363
January	1st to 10th	Night	22% 14% 31% 28% 5%	988
	11th to 20th	Night	21% 14% 31% 26% 7%	915
	21st to end	Night	25% 14% 32% 25% 4	924
February	1st to 10th	Night	20% 12% 33% 30% 5%	801
	11th to 20th	Night	24% 16% 28% 26% 5%	783
	21st to end	Night	22% 18% 38% 19% 3	660
March	1st to 10th	Night	18% 17% 31% 28% 7%	800
	11th to 20th	Night	16% 12% 35% 29% 8%	640
	21st to end	Night	16% 11% 35% 27% 11%	660
April	1st to 10th	Night	18% 10% 31% 29% 11% 1	600
	11th to 20th	Night	15% 8% 34% 28% 13% 1	593
	21st to end	Night	9% 7% 29% 38% 16% 1	600
May	1st to 10th	Night	10% 5% 27% 38% 19% 2	600
	11th to 20th	Night	12% 4 20% 40% 20% 4	591
	21st to end	Night	7% 2 17% 34% 33% 6%	650
June	1st to 10th	Night	10% 3 12% 35% 35% 5%	600
	11th to 20th	Night	4 1 10% 31% 43% 11%	600
	21st to end	Night	7% 2 10% 26% 44% 12%	600
July	1st to 10th	Night	5% 1 5% 23% 50% 16%	585
	11th to 20th	Night	7% 1 5% 19% 47% 21%	582
	21st to end	Night	5% 5% 23% 49% 18%	657
August	1st to 10th	Night	4 4 21% 49% 22%	597
	11th to 20th	Night	9% 5% 20% 44% 22%	594
	21st to end	Night	10% 1 7% 19% 43% 19%	660
September	1st to 10th	Night	10% 2 9% 28% 40% 11%	600
	11th to 20th	Night	10% 2 10% 30% 40% 8%	692
	21st to end	Night	11% 3 14% 31% 36% 6%	800
October	1st to 10th	Night	10% 3 18% 31% 34% 4	800
	11th to 20th	Night	10% 5% 20% 34% 27% 3	800
	21st to end	Night	16% 6% 19% 33% 23% 2	880
November	1st to 10th	Night	13% 7% 19% 39% 19% 2	820
	11th to 20th	Night	16% 8% 25% 34% 15% 1	840
	21st to end	Night	15% 10% 27% 30% 16% 2	840
December	1st to 10th	Night	22% 11% 27% 29% 11%	840
	11th to 20th	Night	22% 8% 32% 28% 10%	840
	21st to end	Night	26% 12% 27% 28% 7%	924

Page generated at 2026-01-29 00:21:41. Version ac07

Copyright © 2026 Attilla Danko.