Moonridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Moonridge Observatory clear sky chart from 2005-11-06 to 2024-11-28.

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	14% 6% 2 6% 4 4 5% 4 6% 8% 41%	101422
	Night	14% 7% 2 6% 4 4 4 4 6% 7% 42%	98066
Transparency	Day	39% 7% 12% 24% 16% 3	105063
	Night	39% 6% 12% 24% 16% 3	102564
Seeing	Day	19% 13% 26% 23% 14% 5%	15001
	Night	18% 11% 29% 30% 12% 1	24569

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	17% 5% 2 5% 4 4 5% 4 5% 6% 44%	2647
	11th to 20th	Day	14% 11% 3 7% 5% 5% 5% 4 5% 5% 38%	2840
	21st to end	Day	16% 10% 3 8% 5% 4 5% 3 5% 6% 35%	3124
February	1st to 10th	Day	13% 9% 3 7% 4 6% 5% 4 6% 6% 38%	1710
	11th to 20th	Day	16% 7% 3 7% 5% 3 4 3 5% 8% 39%	1677
	21st to end	Day	17% 9% 3 6% 5% 4 4 3 5% 5% 39%	1570
March	1st to 10th	Day	20% 9% 2 7% 4 5% 5% 3 5% 6% 34%	3435
	11th to 20th	Day	10% 5% 2 5% 4 5% 5% 4 5% 7% 47%	3480
	21st to end	Day	19% 7% 2 7% 4 4 4 4 5% 6% 39%	3835
April	1st to 10th	Day	13% 7% 3 6% 5% 4 5% 4 5% 9% 39%	2280
	11th to 20th	Day	13% 7% 3 5% 4 4 4 4 5% 7% 45%	2254
	21st to end	Day	18% 7% 2 6% 5% 4 4 4 5% 6% 41%	2291
May	1st to 10th	Day	22% 7% 2 7% 5% 5% 5% 4 6% 8% 30%	4082
	11th to 20th	Day	24% 7% 2 5% 5% 4 4 4 6% 8% 31%	4225
	21st to end	Day	11% 5% 2 5% 4 4 5% 4 7% 9% 44%	4823
June	1st to 10th	Day	12% 5% 2 5% 5% 4 5% 5% 7% 9% 43%	2660
	11th to 20th	Day	11% 5% 2 6% 5% 5% 6% 5% 7% 8% 40%	2660
	21st to end	Day	9% 3 1 6% 4 5% 5% 4 7% 10% 44%	2660
July	1st to 10th	Day	6% 4 2 6% 5% 6% 6% 5% 8% 10% 43%	4440
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 4 7% 11% 41%	4226
	21st to end	Day	10% 7% 3 7% 6% 5% 5% 4 6% 8% 38%	4466
August	1st to 10th	Day	16% 5% 2 7% 5% 6% 5% 5% 7% 9% 35%	4104
	11th to 20th	Day	9% 5% 2 7% 5% 5% 6% 4 7% 9% 42%	3930
	21st to end	Day	11% 5% 2 5% 4 4 4 4 6% 7% 48%	4180
September	1st to 10th	Day	16% 5% 2 5% 4 3 4 4 5% 6% 46%	2280
	11th to 20th	Day	13% 5% 2 6% 3 4 4 3 6% 7% 48%	2271
	21st to end	Day	21% 6% 2 6% 4 4 4 3 5% 6% 38%	1987
October	1st to 10th	Day	16% 6% 2 6% 3 3 3 3 4 7% 46%	1900
	11th to 20th	Day	16% 4 3 5% 3 3 4 4 5% 5% 49%	1900
	21st to end	Day	14% 5% 2 5% 4 4 4 3 4 6% 50%	2090
November	1st to 10th	Day	11% 7% 2 4 3 3 3 4 5% 7% 51%	1892
	11th to 20th	Day	15% 6% 2 5% 3 3 4 4 6% 6% 47%	1725
	21st to end	Day	15% 6% 2 5% 3 5% 4 4 5% 7% 44%	1576
December	1st to 10th	Day	16% 8% 3 6% 5% 5% 5% 4 5% 7% 37%	1520
	11th to 20th	Day	16% 4 2 6% 4 4 5% 3 7% 7% 42%	1910
	21st to end	Day	17% 6% 2 6% 5% 5% 6% 5% 7% 8% 33%	2772
January	1st to 10th	Night	12% 8% 3 6% 5% 4 4 3 5% 7% 42%	4297
	11th to 20th	Night	18% 7% 2 5% 4 3 3 3 5% 7% 43%	4120
	21st to end	Night	18% 9% 3 7% 4 3 4 4 5% 6% 37%	4532
February	1st to 10th	Night	14% 8% 3 6% 4 4 4 3 6% 7% 40%	2470
	11th to 20th	Night	17% 8% 3 6% 4 4 5% 3 5% 5% 41%	2389
	21st to end	Night	17% 9% 2 6% 5% 4 4 4 5% 5% 39%	1879
March	1st to 10th	Night	20% 8% 2 6% 5% 4 4 4 4 6% 37%	3418
	11th to 20th	Night	12% 4 1 5% 4 5% 4 4 6% 7% 48%	3480
	21st to end	Night	14% 9% 3 5% 4 4 3 2 4 5% 47%	3796
April	1st to 10th	Night	15% 8% 2 6% 5% 4 4 4 6% 6% 39%	1900
	11th to 20th	Night	13% 5% 2 7% 5% 4 4 4 6% 8% 44%	1875
	21st to end	Night	16% 5% 2 5% 3 4 4 4 5% 8% 43%	1900
May	1st to 10th	Night	22% 9% 3 8% 5% 4 5% 3 5% 7% 31%	2818
	11th to 20th	Night	24% 9% 3 7% 4 4 4 4 5% 6% 31%	2667
	21st to end	Night	10% 5% 2 7% 4 4 5% 5% 8% 10% 41%	2732
June	1st to 10th	Night	11% 5% 2 6% 4 4 5% 4 7% 8% 45%	1520
	11th to 20th	Night	12% 5% 2 6% 4 3 4 5% 8% 10% 41%	1520
	21st to end	Night	8% 5% 2 5% 4 4 5% 3 7% 11% 44%	1520
July	1st to 10th	Night	6% 5% 2 7% 5% 6% 7% 6% 8% 11% 38%	2520
	11th to 20th	Night	6% 5% 2 7% 6% 6% 6% 5% 9% 10% 39%	2730
	21st to end	Night	10% 6% 3 6% 5% 5% 6% 5% 6% 9% 39%	3087
August	1st to 10th	Night	15% 5% 2 8% 5% 6% 6% 4 7% 9% 33%	2825
	11th to 20th	Night	9% 8% 3 6% 5% 5% 5% 4 7% 8% 40%	2865
	21st to end	Night	12% 5% 2 5% 3 4 4 4 6% 8% 47%	3476
September	1st to 10th	Night	15% 5% 2 5% 4 4 4 4 6% 7% 44%	1900
	11th to 20th	Night	11% 5% 3 6% 3 4 4 2 3 6% 52%	1906
	21st to end	Night	21% 7% 2 7% 4 4 3 2 5% 6% 41%	2192
October	1st to 10th	Night	19% 5% 2 5% 3 3 4 3 4 6% 46%	2280
	11th to 20th	Night	14% 5% 1 4 3 3 4 3 4 6% 52%	2280
	21st to end	Night	15% 5% 2 5% 3 2 3 2 5% 6% 51%	2508
November	1st to 10th	Night	11% 6% 2 5% 3 3 3 3 4 6% 54%	2406
	11th to 20th	Night	14% 6% 2 4 4 3 4 4 5% 6% 48%	2670
	21st to end	Night	13% 5% 2 5% 5% 4 5% 4 5% 7% 46%	2759
December	1st to 10th	Night	16% 7% 2 7% 5% 4 4 4 5% 6% 39%	2660
	11th to 20th	Night	16% 6% 2 6% 4 4 4 3 6% 7% 41%	3285
	21st to end	Night	16% 7% 2 6% 4 5% 6% 5% 7% 9% 34%	4884

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	39% 5% 10% 30% 13% 4	2648
	11th to 20th	Day	46% 5% 10% 20% 14% 5%	2840
	21st to end	Day	48% 5% 12% 22% 11% 2	3124
February	1st to 10th	Day	44% 6% 14% 22% 12% 2	1710
	11th to 20th	Day	44% 5% 10% 23% 15% 2	1686
	21st to end	Day	46% 6% 11% 19% 15% 3	1570
March	1st to 10th	Day	47% 7% 11% 20% 13% 3	3435
	11th to 20th	Day	32% 6% 10% 27% 20% 4	3480
	21st to end	Day	45% 6% 11% 20% 15% 3	3835
April	1st to 10th	Day	40% 7% 13% 18% 18% 4	2280
	11th to 20th	Day	37% 6% 11% 22% 18% 5%	2254
	21st to end	Day	43% 7% 9% 22% 16% 4	2291
May	1st to 10th	Day	50% 8% 11% 20% 10% 1	4120
	11th to 20th	Day	48% 9% 13% 21% 8% 1	4229
	21st to end	Day	32% 9% 16% 24% 17% 2	4837
June	1st to 10th	Day	35% 9% 15% 25% 16% 1	2660
	11th to 20th	Day	36% 10% 15% 23% 14% 2	2660
	21st to end	Day	32% 9% 15% 26% 16% 2	2660
July	1st to 10th	Day	34% 10% 16% 24% 11% 5%	4370
	11th to 20th	Day	35% 8% 14% 29% 12% 1	4153
	21st to end	Day	42% 7% 10% 21% 18% 1	4324
August	1st to 10th	Day	44% 8% 15% 24% 8% 1	4091
	11th to 20th	Day	36% 8% 12% 28% 15% 1	3969
	21st to end	Day	34% 7% 13% 27% 18% 2	4180
September	1st to 10th	Day	38% 6% 12% 19% 21% 4	2280
	11th to 20th	Day	35% 6% 9% 26% 21% 3	2271
	21st to end	Day	46% 6% 10% 18% 18% 2	1987
October	1st to 10th	Day	36% 4 8% 20% 28% 5%	3160
	11th to 20th	Day	26% 3 9% 28% 24% 9%	3140
	21st to end	Day	24% 3 11% 30% 28% 5%	3428
November	1st to 10th	Day	32% 4 13% 26% 21% 4	1892
	11th to 20th	Day	36% 4 12% 23% 22% 4	1725
	21st to end	Day	39% 5% 12% 28% 15% 2	1576
December	1st to 10th	Day	45% 6% 13% 23% 11% 2	1520
	11th to 20th	Day	39% 6% 12% 30% 10% 3	1906
	21st to end	Day	44% 7% 17% 23% 9% 1	2772
January	1st to 10th	Night	38% 6% 12% 27% 16% 3	4297
	11th to 20th	Night	41% 4 11% 26% 16% 3	4120
	21st to end	Night	46% 4 10% 27% 12% 1	4532
February	1st to 10th	Night	42% 5% 13% 24% 14% 2	2470
	11th to 20th	Night	44% 5% 10% 22% 15% 4	2391
	21st to end	Night	45% 4 12% 21% 13% 5%	1879
March	1st to 10th	Night	46% 5% 11% 26% 11% 1	3418
	11th to 20th	Night	32% 6% 10% 29% 20% 2	3480
	21st to end	Night	40% 4 10% 23% 19% 5%	3796
April	1st to 10th	Night	42% 7% 10% 20% 18% 4	1900
	11th to 20th	Night	37% 6% 12% 20% 18% 6%	1875
	21st to end	Night	38% 6% 13% 26% 13% 4	1900
May	1st to 10th	Night	52% 7% 10% 19% 9% 3	2845
	11th to 20th	Night	50% 9% 12% 19% 9% 1	2668
	21st to end	Night	33% 10% 18% 25% 11% 3	2739
June	1st to 10th	Night	34% 9% 12% 26% 17% 2	1520
	11th to 20th	Night	36% 9% 15% 24% 14% 2	1520
	21st to end	Night	33% 7% 16% 25% 17% 2	1520
July	1st to 10th	Night	37% 10% 19% 18% 12% 5%	2480
	11th to 20th	Night	37% 10% 17% 21% 13% 1	2680
	21st to end	Night	39% 9% 15% 20% 16% 1	2988
August	1st to 10th	Night	45% 8% 16% 21% 8% 1	2814
	11th to 20th	Night	39% 7% 12% 26% 14% 1	2892
	21st to end	Night	34% 6% 13% 29% 16% 2	3476
September	1st to 10th	Night	37% 7% 12% 20% 19% 5%	1900
	11th to 20th	Night	33% 5% 10% 26% 23% 2	1906
	21st to end	Night	45% 5% 10% 19% 18% 3	2192
October	1st to 10th	Night	40% 4 10% 22% 21% 3	3800
	11th to 20th	Night	24% 4 11% 23% 31% 7%	3779
	21st to end	Night	23% 3 10% 31% 27% 5%	4120
November	1st to 10th	Night	31% 4 11% 26% 23% 5%	2406
	11th to 20th	Night	35% 4 9% 25% 21% 6%	2670
	21st to end	Night	36% 5% 13% 24% 18% 3	2759
December	1st to 10th	Night	44% 5% 12% 25% 13% 1	2660
	11th to 20th	Night	41% 5% 11% 24% 17% 3	3288
	21st to end	Night	41% 9% 18% 19% 12% 1	4884

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% 29% 28% 13% 3	218
	11th to 20th	Day	30% 27% 29% 11% 3	270
	21st to end	Day	26% 30% 31% 10% 3 1	297
February	1st to 10th	Day	21% 29% 34% 12% 4	270
	11th to 20th	Day	33% 29% 30% 6% 1	284
	21st to end	Day	30% 19% 32% 15% 3	382
March	1st to 10th	Day	24% 24% 27% 21% 3	460
	11th to 20th	Day	25% 22% 31% 16% 4 2	460
	21st to end	Day	22% 21% 33% 18% 5% 1	506
April	1st to 10th	Day	22% 25% 26% 19% 7% 1	460
	11th to 20th	Day	17% 18% 29% 19% 13% 3	452
	21st to end	Day	26% 17% 26% 19% 8% 2	460
May	1st to 10th	Day	25% 17% 26% 19% 10% 3	463
	11th to 20th	Day	21% 14% 25% 22% 14% 4	487
	21st to end	Day	18% 8% 24% 24% 21% 6%	529
June	1st to 10th	Day	14% 9% 27% 25% 18% 6%	490
	11th to 20th	Day	12% 8% 28% 29% 18% 5%	490
	21st to end	Day	10% 7% 28% 31% 18% 6%	490
July	1st to 10th	Day	11% 5% 17% 28% 27% 12%	485
	11th to 20th	Day	7% 3 19% 31% 32% 8%	484
	21st to end	Day	12% 4 21% 32% 24% 8%	532
August	1st to 10th	Day	13% 4 20% 25% 25% 13%	486
	11th to 20th	Day	12% 4 21% 29% 23% 11%	479
	21st to end	Day	9% 4 20% 30% 22% 15%	539
September	1st to 10th	Day	19% 6% 19% 22% 24% 10%	490
	11th to 20th	Day	14% 4 19% 31% 20% 12%	490
	21st to end	Day	26% 10% 22% 25% 13% 4	490
October	1st to 10th	Day	19% 8% 20% 28% 19% 6%	490
	11th to 20th	Day	17% 14% 25% 29% 12% 3	490
	21st to end	Day	16% 13% 33% 24% 11% 3	539
November	1st to 10th	Day	17% 12% 31% 26% 11% 3	462
	11th to 20th	Day	21% 15% 33% 22% 9% 1	325
	21st to end	Day	21% 22% 30% 20% 6% 1	194
December	1st to 10th	Day	21% 24% 36% 15% 3 1	180
	11th to 20th	Day	23% 25% 26% 21% 6%	180
	21st to end	Day	22% 21% 32% 18% 7% 1	198
January	1st to 10th	Night	19% 20% 40% 18% 3	760
	11th to 20th	Night	24% 16% 31% 26% 4	760
	21st to end	Night	19% 18% 40% 21% 2	836
February	1st to 10th	Night	17% 19% 36% 27% 2	760
	11th to 20th	Night	24% 22% 36% 17% 2	743
	21st to end	Night	25% 18% 37% 17% 3	628
March	1st to 10th	Night	21% 17% 37% 22% 3	760
	11th to 20th	Night	24% 19% 30% 21% 5% 1	760
	21st to end	Night	20% 17% 37% 21% 4 1	836
April	1st to 10th	Night	19% 19% 35% 23% 4	760
	11th to 20th	Night	16% 12% 35% 29% 7%	751
	21st to end	Night	19% 12% 32% 29% 7%	760
May	1st to 10th	Night	22% 8% 26% 33% 11%	575
	11th to 20th	Night	21% 7% 24% 37% 10% 1	481
	21st to end	Night	14% 4 24% 39% 18% 1	411
June	1st to 10th	Night	11% 3 25% 38% 22% 1	380
	11th to 20th	Night	13% 5% 19% 41% 20% 1	380
	21st to end	Night	9% 4 23% 45% 19% 1	380
July	1st to 10th	Night	10% 3 17% 40% 27% 3	370
	11th to 20th	Night	7% 1 12% 42% 34% 3	485
	21st to end	Night	8% 2 16% 43% 28% 3	624
August	1st to 10th	Night	10% 2 11% 45% 28% 3	567
	11th to 20th	Night	10% 4 14% 40% 30% 3	605
	21st to end	Night	14% 3 15% 38% 26% 3	836
September	1st to 10th	Night	16% 2 19% 34% 26% 3	760
	11th to 20th	Night	13% 3 18% 35% 27% 3	760
	21st to end	Night	23% 5% 20% 30% 21% 1	760
October	1st to 10th	Night	21% 6% 22% 29% 20% 3	760
	11th to 20th	Night	15% 12% 27% 32% 13% 1	760
	21st to end	Night	18% 9% 32% 29% 11%	836
November	1st to 10th	Night	13% 9% 34% 33% 10% 1	780
	11th to 20th	Night	18% 14% 32% 28% 7% 1	800
	21st to end	Night	16% 16% 33% 28% 7%	789
December	1st to 10th	Night	22% 16% 34% 22% 7%	760
	11th to 20th	Night	19% 11% 40% 25% 4	760
	21st to end	Night	20% 13% 35% 30% 2	836

Page generated at 2024-11-25 00:22:18. Version ac07

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