Waning Moon II Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waning Moon II Observatory clear sky chart from 2005-11-06 to 2024-11-10.

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 7% 5% 5% 5% 5% 7% 9% 39%	100801
	Night	11% 6% 2 5% 4 4 4 4 6% 8% 45%	98259
Transparency	Day	36% 9% 14% 18% 16% 6%	104563
	Night	34% 8% 14% 19% 18% 8%	102636
Seeing	Day	12% 6% 18% 27% 26% 12%	14615
	Night	12% 5% 18% 30% 26% 8%	24034

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% 2 6% 4 4 5% 4 6% 7% 42%	3156
	11th to 20th	Day	12% 6% 2 5% 3 3 3 3 4 5% 55%	3160
	21st to end	Day	24% 7% 3 6% 4 4 3 3 4 5% 37%	3476
February	1st to 10th	Day	17% 8% 3 8% 4 4 4 3 6% 4 40%	1900
	11th to 20th	Day	17% 7% 2 5% 3 3 3 3 5% 7% 44%	1848
	21st to end	Day	16% 7% 2 9% 5% 5% 3 4 4 7% 37%	1570
March	1st to 10th	Day	23% 10% 3 7% 4 4 4 4 6% 7% 29%	3205
	11th to 20th	Day	14% 7% 3 8% 4 4 6% 4 7% 8% 35%	3480
	21st to end	Day	11% 6% 3 6% 4 5% 6% 4 6% 7% 41%	4037
April	1st to 10th	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 7% 40%	2280
	11th to 20th	Day	14% 7% 3 6% 5% 4 4 4 7% 7% 40%	2254
	21st to end	Day	9% 5% 1 5% 5% 4 4 5% 6% 9% 46%	2280
May	1st to 10th	Day	10% 5% 2 7% 5% 6% 6% 5% 8% 9% 38%	3765
	11th to 20th	Day	13% 6% 2 6% 5% 4 5% 4 6% 8% 41%	3764
	21st to end	Day	5% 4 2 6% 5% 5% 5% 5% 8% 11% 45%	4129
June	1st to 10th	Day	9% 6% 2 7% 5% 7% 7% 6% 9% 10% 30%	2403
	11th to 20th	Day	4 5% 2 7% 6% 7% 8% 6% 9% 12% 33%	2459
	21st to end	Day	6% 7% 2 8% 7% 8% 7% 7% 10% 10% 27%	2470
July	1st to 10th	Day	6% 7% 3 9% 7% 8% 8% 7% 9% 13% 23%	4120
	11th to 20th	Day	6% 5% 2 8% 7% 7% 9% 7% 9% 13% 27%	3906
	21st to end	Day	6% 7% 3 8% 8% 8% 8% 7% 11% 13% 22%	4118
August	1st to 10th	Day	3 3 1 5% 4 5% 6% 5% 8% 11% 49%	3785
	11th to 20th	Day	6% 4 2 7% 6% 5% 7% 6% 9% 13% 36%	3729
	21st to end	Day	7% 6% 3 11% 7% 7% 7% 6% 7% 9% 31%	4180
September	1st to 10th	Day	10% 7% 2 9% 6% 6% 7% 6% 8% 8% 32%	2280
	11th to 20th	Day	10% 7% 3 7% 5% 6% 6% 5% 7% 9% 37%	2199
	21st to end	Day	7% 5% 2 6% 4 4 6% 4 6% 8% 47%	2090
October	1st to 10th	Day	6% 4 2 5% 4 4 4 4 6% 7% 55%	2057
	11th to 20th	Day	5% 4 2 5% 4 4 4 3 4 9% 57%	1900
	21st to end	Day	10% 4 1 5% 4 3 3 3 4 7% 56%	2090
November	1st to 10th	Day	9% 5% 2 4 3 3 4 4 6% 6% 54%	1948
	11th to 20th	Day	11% 4 2 5% 3 4 3 3 4 6% 55%	1764
	21st to end	Day	12% 7% 2 6% 4 4 5% 3 6% 7% 45%	1710
December	1st to 10th	Day	14% 7% 2 6% 5% 4 4 3 6% 6% 43%	1710
	11th to 20th	Day	14% 8% 3 7% 5% 4 4 4 6% 6% 39%	2153
	21st to end	Day	17% 8% 2 7% 4 5% 4 4 5% 6% 38%	3426
January	1st to 10th	Night	16% 7% 2 5% 3 4 3 3 5% 6% 46%	3789
	11th to 20th	Night	15% 6% 2 4 3 3 3 3 4 5% 53%	3800
	21st to end	Night	26% 7% 2 5% 2 2 3 2 4 6% 40%	4180
February	1st to 10th	Night	17% 7% 2 6% 4 4 3 4 5% 6% 43%	2280
	11th to 20th	Night	18% 8% 3 5% 4 3 3 4 5% 6% 42%	2218
	21st to end	Night	19% 9% 3 5% 4 4 4 4 5% 7% 38%	1884
March	1st to 10th	Night	24% 11% 4 7% 4 4 4 3 5% 6% 30%	3674
	11th to 20th	Night	15% 8% 2 6% 5% 4 5% 4 5% 8% 37%	3480
	21st to end	Night	14% 6% 2 5% 4 4 4 3 6% 7% 45%	3578
April	1st to 10th	Night	14% 6% 2 6% 4 3 4 4 5% 6% 46%	1900
	11th to 20th	Night	12% 6% 2 7% 5% 5% 3 4 6% 7% 44%	1875
	21st to end	Night	7% 4 1 5% 3 4 4 3 6% 8% 56%	1900
May	1st to 10th	Night	12% 6% 2 6% 4 4 4 3 5% 9% 44%	3130
	11th to 20th	Night	14% 6% 2 7% 4 4 4 4 6% 7% 43%	3129
	21st to end	Night	6% 4 2 4 4 4 4 4 8% 14% 46%	3426
June	1st to 10th	Night	7% 6% 1 5% 4 5% 6% 5% 8% 10% 42%	1760
	11th to 20th	Night	3 4 2 4 4 5% 5% 6% 8% 13% 45%	1692
	21st to end	Night	6% 5% 3 6% 6% 5% 5% 5% 9% 11% 41%	1710
July	1st to 10th	Night	4 5% 2 6% 5% 5% 7% 7% 8% 14% 37%	2850
	11th to 20th	Night	3 3 1 6% 5% 4 6% 5% 8% 13% 45%	3053
	21st to end	Night	5% 4 2 7% 6% 6% 7% 6% 11% 16% 30%	3435
August	1st to 10th	Night	1 2 1 4 3 4 5% 5% 8% 12% 56%	3144
	11th to 20th	Night	3 3 1 5% 4 5% 6% 4 10% 14% 45%	3100
	21st to end	Night	5% 4 2 7% 6% 5% 6% 5% 8% 10% 41%	3476
September	1st to 10th	Night	8% 6% 2 7% 4 6% 6% 5% 8% 10% 39%	1900
	11th to 20th	Night	8% 6% 2 6% 4 4 4 4 7% 10% 44%	1962
	21st to end	Night	7% 5% 2 5% 3 5% 4 3 6% 8% 53%	2090
October	1st to 10th	Night	6% 4 2 5% 3 3 4 3 5% 7% 58%	2118
	11th to 20th	Night	5% 4 1 4 3 3 3 3 5% 7% 61%	2280
	21st to end	Night	11% 4 2 5% 4 3 3 2 4 5% 58%	2508
November	1st to 10th	Night	10% 6% 2 5% 3 3 3 2 4 5% 57%	2335
	11th to 20th	Night	12% 4 1 4 3 3 4 3 5% 5% 56%	2412
	21st to end	Night	11% 6% 2 6% 5% 3 4 3 5% 6% 48%	2470
December	1st to 10th	Night	14% 6% 3 7% 4 3 3 3 5% 7% 44%	2470
	11th to 20th	Night	14% 8% 2 6% 5% 4 4 4 5% 6% 43%	3042
	21st to end	Night	18% 10% 3 7% 4 4 4 3 5% 5% 39%	4209

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	40% 6% 8% 15% 22% 10%	3157
	11th to 20th	Day	31% 5% 7% 16% 31% 9%	3160
	21st to end	Day	48% 6% 4 16% 18% 8%	3476
February	1st to 10th	Day	45% 6% 9% 13% 18% 10%	1900
	11th to 20th	Day	39% 7% 8% 17% 19% 10%	1858
	21st to end	Day	45% 7% 9% 14% 17% 8%	1570
March	1st to 10th	Day	51% 7% 10% 17% 11% 4	3205
	11th to 20th	Day	41% 9% 11% 19% 16% 4	3480
	21st to end	Day	36% 10% 13% 15% 19% 8%	4037
April	1st to 10th	Day	36% 9% 12% 17% 17% 9%	2280
	11th to 20th	Day	39% 7% 10% 19% 18% 7%	2254
	21st to end	Day	29% 6% 14% 22% 22% 6%	2280
May	1st to 10th	Day	34% 11% 19% 21% 12% 4	3800
	11th to 20th	Day	35% 9% 14% 19% 21% 2	3768
	21st to end	Day	26% 9% 19% 35% 10% 1	4141
June	1st to 10th	Day	38% 11% 17% 23% 10% 1	2403
	11th to 20th	Day	33% 13% 18% 24% 11% 1	2459
	21st to end	Day	41% 14% 20% 17% 8%	2470
July	1st to 10th	Day	44% 14% 24% 15% 2	4056
	11th to 20th	Day	38% 17% 35% 9% 1	3839
	21st to end	Day	44% 16% 22% 15% 3	3987
August	1st to 10th	Day	21% 11% 17% 29% 22%	3773
	11th to 20th	Day	31% 13% 21% 27% 7% 1	3765
	21st to end	Day	44% 12% 14% 16% 13% 1	4179
September	1st to 10th	Day	40% 12% 18% 16% 10% 4	2280
	11th to 20th	Day	36% 11% 16% 17% 14% 6%	2199
	21st to end	Day	30% 9% 13% 23% 16% 9%	2090
October	1st to 10th	Day	25% 5% 9% 14% 20% 27%	3421
	11th to 20th	Day	14% 3 6% 23% 26% 28%	3140
	21st to end	Day	19% 4 6% 12% 42% 17%	3428
November	1st to 10th	Day	27% 6% 9% 21% 26% 10%	1948
	11th to 20th	Day	31% 5% 6% 19% 28% 12%	1764
	21st to end	Day	36% 6% 8% 19% 20% 11%	1710
December	1st to 10th	Day	39% 8% 8% 19% 18% 7%	1710
	11th to 20th	Day	43% 5% 10% 13% 21% 9%	2150
	21st to end	Day	44% 7% 9% 15% 21% 3	3426
January	1st to 10th	Night	38% 5% 7% 15% 24% 11%	3789
	11th to 20th	Night	33% 4 7% 17% 30% 9%	3800
	21st to end	Night	46% 4 6% 14% 22% 9%	4180
February	1st to 10th	Night	43% 4 8% 17% 19% 9%	2280
	11th to 20th	Night	41% 6% 7% 15% 19% 12%	2219
	21st to end	Night	43% 7% 10% 15% 13% 11%	1884
March	1st to 10th	Night	52% 7% 11% 12% 13% 5%	3674
	11th to 20th	Night	40% 9% 12% 16% 16% 6%	3480
	21st to end	Night	36% 7% 11% 20% 19% 7%	3578
April	1st to 10th	Night	37% 8% 12% 16% 16% 11%	1900
	11th to 20th	Night	38% 6% 9% 21% 16% 9%	1875
	21st to end	Night	25% 6% 13% 23% 26% 8%	1900
May	1st to 10th	Night	34% 9% 15% 22% 16% 4	3160
	11th to 20th	Night	38% 9% 13% 22% 18% 2	3130
	21st to end	Night	26% 9% 20% 31% 12% 2	3435
June	1st to 10th	Night	32% 9% 21% 27% 11%	1760
	11th to 20th	Night	26% 11% 22% 28% 11% 1	1692
	21st to end	Night	33% 12% 24% 22% 9%	1710
July	1st to 10th	Night	33% 15% 33% 16% 2	2805
	11th to 20th	Night	26% 17% 45% 10% 2	2997
	21st to end	Night	37% 20% 23% 18% 2	3325
August	1st to 10th	Night	18% 10% 22% 28% 21% 1	3132
	11th to 20th	Night	24% 13% 29% 28% 6%	3130
	21st to end	Night	36% 12% 19% 19% 11% 3	3476
September	1st to 10th	Night	36% 12% 19% 17% 12% 5%	1900
	11th to 20th	Night	35% 10% 17% 18% 14% 8%	1962
	21st to end	Night	29% 7% 13% 26% 16% 10%	2090
October	1st to 10th	Night	28% 5% 8% 14% 23% 23%	3534
	11th to 20th	Night	16% 4 6% 20% 28% 27%	3779
	21st to end	Night	19% 3 6% 10% 39% 23%	4120
November	1st to 10th	Night	30% 3 8% 20% 25% 13%	2335
	11th to 20th	Night	30% 4 8% 17% 27% 14%	2412
	21st to end	Night	35% 6% 7% 19% 21% 11%	2470
December	1st to 10th	Night	39% 6% 9% 20% 20% 6%	2470
	11th to 20th	Night	41% 5% 10% 14% 17% 14%	3044
	21st to end	Night	46% 6% 8% 16% 18% 6%	4209

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	20% 12% 38% 24% 6%	270
	11th to 20th	Day	16% 16% 30% 30% 7% 1	270
	21st to end	Day	21% 17% 39% 20% 3	297
February	1st to 10th	Day	24% 16% 32% 23% 4 1	270
	11th to 20th	Day	23% 15% 31% 24% 7%	270
	21st to end	Day	14% 20% 43% 21% 2	225
March	1st to 10th	Day	14% 14% 41% 27% 4	270
	11th to 20th	Day	17% 17% 33% 27% 6%	270
	21st to end	Day	14% 10% 35% 27% 13%	430
April	1st to 10th	Day	15% 11% 31% 32% 11% 1	460
	11th to 20th	Day	15% 13% 30% 28% 12% 2	452
	21st to end	Day	10% 7% 25% 36% 20% 3	460
May	1st to 10th	Day	10% 6% 22% 37% 20% 4	463
	11th to 20th	Day	11% 4 18% 29% 30% 8%	487
	21st to end	Day	5% 2 12% 37% 32% 12%	529
June	1st to 10th	Day	11% 3 8% 30% 32% 16%	490
	11th to 20th	Day	9% 1 9% 25% 39% 16%	537
	21st to end	Day	8% 2 8% 25% 37% 20%	680
July	1st to 10th	Day	8% 3 5% 21% 38% 25%	671
	11th to 20th	Day	7% 2 3 12% 45% 31%	547
	21st to end	Day	8% 1 4 17% 43% 27%	532
August	1st to 10th	Day	6% 1 3 18% 41% 31%	486
	11th to 20th	Day	8% 1 3 12% 42% 35%	479
	21st to end	Day	10% 2 7% 19% 38% 24%	539
September	1st to 10th	Day	9% 1 7% 20% 42% 20%	490
	11th to 20th	Day	12% 3 9% 22% 39% 15%	490
	21st to end	Day	10% 2 10% 26% 40% 11%	490
October	1st to 10th	Day	6% 2 14% 40% 32% 6%	457
	11th to 20th	Day	5% 4 15% 43% 26% 6%	300
	21st to end	Day	15% 7% 15% 38% 21% 4	330
November	1st to 10th	Day	14% 3 18% 37% 25% 3	297
	11th to 20th	Day	16% 8% 25% 34% 16% 1	270
	21st to end	Day	14% 6% 32% 35% 10% 3	270
December	1st to 10th	Day	17% 7% 30% 29% 15% 1	270
	11th to 20th	Day	21% 11% 31% 30% 8%	270
	21st to end	Day	23% 9% 30% 27% 10% 1	297
January	1st to 10th	Night	19% 9% 31% 34% 7% 1	760
	11th to 20th	Night	18% 8% 28% 36% 10%	760
	21st to end	Night	22% 9% 31% 32% 6%	836
February	1st to 10th	Night	19% 8% 34% 32% 8%	760
	11th to 20th	Night	20% 11% 30% 30% 9%	743
	21st to end	Night	21% 11% 33% 31% 4	628
March	1st to 10th	Night	17% 9% 32% 32% 9%	727
	11th to 20th	Night	15% 6% 28% 36% 15% 1	570
	21st to end	Night	14% 7% 28% 35% 16% 1	627
April	1st to 10th	Night	14% 11% 26% 34% 15% 1	570
	11th to 20th	Night	13% 7% 30% 30% 18% 1	563
	21st to end	Night	8% 5% 20% 43% 21% 2	570
May	1st to 10th	Night	10% 2 19% 42% 26% 1	570
	11th to 20th	Night	6% 4 13% 42% 30% 5%	561
	21st to end	Night	5% 2 10% 33% 41% 9%	617
June	1st to 10th	Night	9% 1 7% 31% 42% 11%	570
	11th to 20th	Night	4 2 5% 24% 53% 12%	570
	21st to end	Night	7% 1 6% 22% 43% 20%	570
July	1st to 10th	Night	5% 1 4 14% 51% 24%	555
	11th to 20th	Night	4 1 2 9% 49% 36%	552
	21st to end	Night	4 3 14% 52% 26%	624
August	1st to 10th	Night	2 1 14% 48% 34%	567
	11th to 20th	Night	5% 2 11% 49% 32%	564
	21st to end	Night	9% 1 5% 16% 43% 26%	627
September	1st to 10th	Night	10% 1 4 15% 47% 22%	570
	11th to 20th	Night	10% 3 7% 24% 46% 10%	632
	21st to end	Night	9% 1 8% 31% 43% 8%	760
October	1st to 10th	Night	7% 2 13% 36% 36% 7%	760
	11th to 20th	Night	7% 4 17% 37% 29% 6%	760
	21st to end	Night	11% 5% 18% 35% 28% 3	836
November	1st to 10th	Night	12% 5% 16% 41% 23% 3	779
	11th to 20th	Night	12% 6% 23% 38% 18% 2	760
	21st to end	Night	13% 7% 26% 35% 18% 1	760
December	1st to 10th	Night	16% 7% 26% 32% 17% 2	760
	11th to 20th	Night	19% 5% 25% 38% 11% 1	760
	21st to end	Night	24% 9% 27% 30% 10%	836

Page generated at 2024-11-07 05:55:49. Version ac07

Copyright © 2024 Attilla Danko.