Manning
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Manning clear sky chart from 2005-11-06 to 2024-11-30.

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% 8% 3 8% 5% 4 5% 4 5% 7% 40%	101535
	Night	11% 8% 3 8% 4 4 4 3 5% 6% 44%	98158
Transparency	Day	42% 6% 12% 25% 14% 2	105179
	Night	39% 5% 12% 25% 16% 2	102655
Seeing	Day	15% 10% 32% 27% 13% 3	15932
	Night	14% 10% 35% 30% 10% 1	25824

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	7% 12% 5% 19% 11% 6% 5% 3 5% 5% 22%	2691
	11th to 20th	Day	8% 12% 5% 12% 7% 6% 9% 3 4 7% 26%	2850
	21st to end	Day	11% 13% 7% 18% 7% 5% 4 3 5% 6% 21%	3135
February	1st to 10th	Day	10% 13% 5% 10% 7% 6% 4 4 5% 8% 28%	1710
	11th to 20th	Day	10% 11% 4 10% 5% 4 5% 3 5% 6% 38%	1664
	21st to end	Day	12% 11% 3 9% 6% 5% 4 4 5% 6% 34%	1530
March	1st to 10th	Day	13% 9% 3 8% 4 3 3 2 4 5% 45%	3436
	11th to 20th	Day	12% 8% 3 7% 4 4 4 3 5% 5% 44%	3480
	21st to end	Day	23% 13% 6% 10% 5% 4 5% 4 5% 4 21%	3814
April	1st to 10th	Day	16% 11% 3 6% 5% 4 4 3 5% 6% 38%	2203
	11th to 20th	Day	17% 11% 2 8% 5% 4 4 3 4 6% 37%	2303
	21st to end	Day	22% 8% 3 6% 4 4 5% 4 4 6% 35%	2470
May	1st to 10th	Day	19% 8% 2 7% 5% 5% 5% 4 5% 6% 32%	4082
	11th to 20th	Day	14% 7% 3 6% 4 5% 5% 4 4 6% 43%	4140
	21st to end	Day	15% 6% 3 7% 4 4 5% 4 6% 7% 40%	4824
June	1st to 10th	Day	11% 5% 2 5% 5% 5% 4 3 6% 8% 45%	2660
	11th to 20th	Day	10% 4 1 5% 5% 4 5% 5% 7% 9% 46%	2660
	21st to end	Day	8% 5% 2 5% 5% 5% 6% 5% 6% 6% 47%	2660
July	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 5% 8% 8% 40%	4440
	11th to 20th	Day	7% 3 2 4 3 3 4 3 5% 7% 59%	4184
	21st to end	Day	4 3 1 5% 4 4 5% 4 8% 10% 50%	4465
August	1st to 10th	Day	9% 5% 2 5% 4 4 5% 5% 6% 9% 45%	4104
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 6% 6% 41%	4041
	21st to end	Day	8% 5% 2 6% 4 4 4 4 7% 8% 47%	4382
September	1st to 10th	Day	11% 5% 2 5% 3 3 4 3 5% 6% 53%	2280
	11th to 20th	Day	10% 5% 1 5% 3 4 4 3 4 7% 54%	2109
	21st to end	Day	11% 4 2 4 3 3 3 3 6% 7% 54%	2082
October	1st to 10th	Day	13% 7% 2 4 3 3 4 2 4 7% 51%	1900
	11th to 20th	Day	13% 7% 2 5% 3 3 3 2 3 6% 52%	1900
	21st to end	Day	15% 8% 3 7% 4 3 4 3 5% 6% 43%	2090
November	1st to 10th	Day	11% 6% 2 6% 5% 3 4 3 5% 7% 48%	1828
	11th to 20th	Day	11% 8% 3 9% 5% 5% 4 3 6% 6% 41%	1600
	21st to end	Day	12% 9% 4 6% 4 4 3 3 6% 6% 42%	1597
December	1st to 10th	Day	10% 9% 4 11% 5% 3 5% 4 5% 6% 38%	1520
	11th to 20th	Day	9% 10% 4 9% 7% 6% 5% 4 6% 7% 32%	1918
	21st to end	Day	17% 12% 5% 20% 5% 4 4 3 5% 5% 21%	2783
January	1st to 10th	Night	8% 11% 4 21% 10% 4 4 3 5% 5% 24%	4263
	11th to 20th	Night	7% 13% 4 10% 7% 4 8% 4 9% 7% 26%	4120
	21st to end	Night	10% 14% 7% 15% 5% 4 5% 3 4 5% 27%	4532
February	1st to 10th	Night	11% 11% 4 11% 7% 5% 5% 3 5% 5% 35%	2470
	11th to 20th	Night	10% 10% 3 7% 5% 5% 5% 3 5% 6% 40%	2403
	21st to end	Night	10% 8% 3 9% 5% 4 4 3 4 6% 44%	1937
March	1st to 10th	Night	12% 7% 3 7% 3 3 3 2 4 5% 50%	3419
	11th to 20th	Night	11% 7% 2 5% 3 3 3 3 4 7% 52%	3480
	21st to end	Night	20% 11% 4 12% 6% 4 4 3 5% 6% 24%	3817
April	1st to 10th	Night	12% 9% 2 6% 4 3 3 4 5% 6% 44%	1976
	11th to 20th	Night	13% 9% 2 7% 5% 4 4 3 4 6% 43%	1824
	21st to end	Night	17% 9% 3 6% 4 4 4 3 5% 7% 38%	1710
May	1st to 10th	Night	20% 7% 2 5% 4 4 3 3 5% 6% 41%	2823
	11th to 20th	Night	12% 6% 2 5% 4 3 4 3 5% 7% 49%	2760
	21st to end	Night	15% 7% 2 6% 4 3 4 3 5% 6% 43%	2743
June	1st to 10th	Night	7% 4 2 5% 4 3 4 4 7% 7% 52%	1520
	11th to 20th	Night	6% 4 2 5% 4 4 4 5% 6% 10% 50%	1520
	21st to end	Night	5% 4 2 5% 4 3 4 4 7% 8% 55%	1520
July	1st to 10th	Night	8% 5% 2 5% 4 3 5% 3 6% 9% 50%	2530
	11th to 20th	Night	5% 3 1 3 3 3 3 3 5% 8% 65%	2781
	21st to end	Night	4 3 1 4 4 3 5% 3 7% 10% 56%	3098
August	1st to 10th	Night	5% 4 2 5% 3 4 4 3 6% 9% 54%	2836
	11th to 20th	Night	11% 7% 2 4 3 3 2 3 5% 8% 52%	2798
	21st to end	Night	8% 5% 2 5% 3 2 3 4 5% 7% 56%	3279
September	1st to 10th	Night	8% 4 1 4 3 4 3 2 5% 6% 60%	1900
	11th to 20th	Night	10% 4 2 4 3 3 4 3 5% 7% 56%	2068
	21st to end	Night	9% 4 2 5% 3 3 3 3 4 6% 58%	2090
October	1st to 10th	Night	13% 6% 2 5% 3 3 3 3 4 7% 53%	2267
	11th to 20th	Night	15% 7% 2 5% 3 2 2 2 3 5% 52%	2280
	21st to end	Night	15% 8% 2 6% 3 3 3 2 3 6% 49%	2508
November	1st to 10th	Night	9% 5% 2 5% 4 3 4 3 5% 6% 54%	2464
	11th to 20th	Night	11% 7% 2 8% 4 3 4 3 5% 6% 46%	2800
	21st to end	Night	11% 10% 3 8% 3 3 4 2 5% 6% 45%	2799
December	1st to 10th	Night	8% 11% 3 9% 6% 4 5% 3 5% 6% 39%	2660
	11th to 20th	Night	9% 10% 4 9% 5% 4 5% 3 5% 7% 39%	3279
	21st to end	Night	17% 13% 5% 17% 5% 4 4 2 3 4 26%	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	65% 5% 11% 13% 6%	2692
	11th to 20th	Day	59% 3 9% 23% 6%	2850
	21st to end	Day	64% 7% 11% 13% 6%	3135
February	1st to 10th	Day	54% 5% 12% 18% 10% 1	1710
	11th to 20th	Day	48% 4 11% 22% 13% 2	1673
	21st to end	Day	50% 5% 11% 20% 10% 4	1530
March	1st to 10th	Day	43% 4 9% 28% 14% 2	3436
	11th to 20th	Day	40% 6% 11% 25% 15% 3	3480
	21st to end	Day	65% 7% 11% 13% 4 1	3814
April	1st to 10th	Day	47% 5% 11% 26% 9% 1	2203
	11th to 20th	Day	49% 4 12% 21% 12% 2	2303
	21st to end	Day	50% 5% 10% 23% 12%	2470
May	1st to 10th	Day	50% 8% 12% 18% 12% 1	4120
	11th to 20th	Day	42% 6% 10% 28% 14% 1	4144
	21st to end	Day	42% 6% 12% 22% 17% 1	4837
June	1st to 10th	Day	36% 7% 16% 26% 13% 2	2660
	11th to 20th	Day	33% 7% 14% 28% 16% 1	2660
	21st to end	Day	34% 8% 15% 27% 13% 3	2660
July	1st to 10th	Day	38% 7% 14% 29% 9% 2	4371
	11th to 20th	Day	24% 6% 14% 32% 21% 3	4113
	21st to end	Day	25% 9% 18% 27% 19% 2	4325
August	1st to 10th	Day	34% 7% 14% 29% 15% 1	4090
	11th to 20th	Day	43% 5% 10% 30% 11% 1	4080
	21st to end	Day	33% 7% 14% 26% 17% 3	4381
September	1st to 10th	Day	31% 5% 11% 29% 19% 4	2280
	11th to 20th	Day	31% 6% 12% 31% 18% 1	2109
	21st to end	Day	29% 5% 12% 30% 24% 1	2082
October	1st to 10th	Day	21% 3 6% 26% 41% 2	3160
	11th to 20th	Day	24% 3 12% 32% 23% 6%	3140
	21st to end	Day	38% 4 7% 28% 19% 4	3428
November	1st to 10th	Day	36% 5% 16% 24% 18% 3	1828
	11th to 20th	Day	44% 4 11% 23% 17% 1	1600
	21st to end	Day	43% 4 15% 25% 13% 1	1597
December	1st to 10th	Day	46% 5% 15% 22% 10% 2	1520
	11th to 20th	Day	50% 5% 17% 23% 5%	1915
	21st to end	Day	65% 5% 9% 15% 6% 1	2783
January	1st to 10th	Night	63% 4 9% 14% 9% 1	4263
	11th to 20th	Night	52% 5% 14% 18% 10% 2	4120
	21st to end	Night	59% 6% 12% 14% 8% 1	4532
February	1st to 10th	Night	51% 5% 11% 20% 11% 2	2470
	11th to 20th	Night	44% 5% 12% 23% 14% 3	2404
	21st to end	Night	43% 3 11% 21% 18% 3	1937
March	1st to 10th	Night	37% 3 9% 29% 18% 3	3419
	11th to 20th	Night	33% 4 11% 33% 14% 5%	3480
	21st to end	Night	60% 8% 15% 12% 4 1	3817
April	1st to 10th	Night	40% 5% 12% 26% 16% 2	1976
	11th to 20th	Night	42% 6% 10% 23% 16% 3	1824
	21st to end	Night	45% 5% 12% 23% 14% 1	1710
May	1st to 10th	Night	42% 6% 11% 21% 17% 2	2850
	11th to 20th	Night	35% 6% 12% 26% 17% 4	2761
	21st to end	Night	41% 6% 12% 21% 17% 3	2751
June	1st to 10th	Night	28% 7% 14% 32% 15% 4	1520
	11th to 20th	Night	27% 9% 14% 25% 21% 4	1520
	21st to end	Night	26% 7% 16% 30% 18% 3	1520
July	1st to 10th	Night	31% 5% 16% 33% 14% 2	2490
	11th to 20th	Night	19% 4 17% 34% 23% 2	2730
	21st to end	Night	22% 9% 17% 33% 18% 2	2999
August	1st to 10th	Night	26% 6% 17% 32% 17% 2	2826
	11th to 20th	Night	32% 6% 14% 30% 16% 2	2825
	21st to end	Night	28% 5% 16% 26% 18% 6%	3279
September	1st to 10th	Night	25% 5% 11% 30% 23% 5%	1900
	11th to 20th	Night	28% 4 12% 33% 20% 2	2068
	21st to end	Night	28% 5% 9% 31% 24% 3	2090
October	1st to 10th	Night	21% 3 6% 21% 46% 3	3787
	11th to 20th	Night	27% 3 10% 26% 28% 6%	3779
	21st to end	Night	37% 3 10% 29% 19% 1	4120
November	1st to 10th	Night	31% 5% 17% 24% 20% 4	2464
	11th to 20th	Night	38% 4 14% 26% 16% 2	2800
	21st to end	Night	40% 4 11% 28% 15% 2	2799
December	1st to 10th	Night	45% 4 13% 27% 10% 1	2660
	11th to 20th	Night	44% 4 14% 30% 7% 1	3281
	21st to end	Night	63% 4 8% 18% 7% 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	16% 16% 37% 22% 8% 1	270
	11th to 20th	Day	19% 13% 42% 21% 4 1	270
	21st to end	Day	18% 11% 43% 23% 5% 1	297
February	1st to 10th	Day	17% 18% 40% 22% 3	270
	11th to 20th	Day	14% 15% 43% 21% 4 1	270
	21st to end	Day	19% 18% 43% 17% 3	225
March	1st to 10th	Day	18% 18% 40% 19% 4 1	270
	11th to 20th	Day	24% 14% 36% 21% 5%	270
	21st to end	Day	33% 18% 31% 16% 2	297
April	1st to 10th	Day	24% 16% 37% 19% 4	383
	11th to 20th	Day	23% 16% 34% 19% 7%	501
	21st to end	Day	23% 16% 31% 22% 6% 2	650
May	1st to 10th	Day	23% 14% 32% 22% 8% 1	653
	11th to 20th	Day	18% 14% 31% 23% 11% 2	675
	21st to end	Day	18% 8% 31% 26% 15% 2	734
June	1st to 10th	Day	8% 6% 28% 32% 23% 3	680
	11th to 20th	Day	10% 7% 35% 31% 15% 3	680
	21st to end	Day	9% 7% 37% 30% 14% 3	680
July	1st to 10th	Day	8% 3 21% 34% 26% 8%	671
	11th to 20th	Day	6% 4 28% 35% 20% 6%	668
	21st to end	Day	6% 3 23% 38% 25% 5%	739
August	1st to 10th	Day	9% 3 22% 36% 24% 5%	676
	11th to 20th	Day	12% 4 20% 37% 22% 4	665
	21st to end	Day	10% 3 22% 39% 20% 5%	663
September	1st to 10th	Day	13% 4 25% 35% 18% 5%	490
	11th to 20th	Day	8% 4 38% 28% 18% 4	319
	21st to end	Day	14% 9% 33% 30% 14% 1	300
October	1st to 10th	Day	19% 8% 31% 24% 15% 3	300
	11th to 20th	Day	15% 18% 37% 21% 8% 1	300
	21st to end	Day	20% 16% 38% 17% 8% 1	330
November	1st to 10th	Day	18% 14% 40% 20% 6% 2	300
	11th to 20th	Day	18% 21% 37% 19% 5%	300
	21st to end	Day	20% 17% 37% 21% 4 1	299
December	1st to 10th	Day	10% 14% 43% 25% 6% 1	270
	11th to 20th	Day	12% 18% 39% 23% 8%	270
	21st to end	Day	24% 18% 43% 14% 2	297
January	1st to 10th	Night	13% 16% 39% 27% 5% 1	950
	11th to 20th	Night	14% 16% 41% 23% 6%	950
	21st to end	Night	18% 12% 41% 24% 5%	1045
February	1st to 10th	Night	16% 12% 42% 25% 4	950
	11th to 20th	Night	16% 12% 43% 23% 5%	929
	21st to end	Night	14% 15% 45% 20% 5% 1	681
March	1st to 10th	Night	17% 11% 38% 26% 6% 1	570
	11th to 20th	Night	19% 10% 39% 24% 8%	570
	21st to end	Night	23% 14% 35% 22% 5% 1	627
April	1st to 10th	Night	18% 16% 39% 23% 4	570
	11th to 20th	Night	18% 11% 40% 26% 5%	563
	21st to end	Night	19% 12% 35% 25% 8% 1	570
May	1st to 10th	Night	19% 8% 36% 30% 7% 1	570
	11th to 20th	Night	15% 9% 30% 35% 9% 1	561
	21st to end	Night	13% 8% 30% 36% 12%	617
June	1st to 10th	Night	8% 4 26% 46% 16%	570
	11th to 20th	Night	7% 5% 35% 41% 12%	570
	21st to end	Night	5% 5% 35% 41% 14%	570
July	1st to 10th	Night	6% 2 19% 44% 28% 1	555
	11th to 20th	Night	4 2 20% 51% 21% 2	552
	21st to end	Night	3 2 18% 52% 24% 1	624
August	1st to 10th	Night	7% 3 22% 43% 23% 2	567
	11th to 20th	Night	9% 4 20% 43% 22% 2	564
	21st to end	Night	8% 3 23% 43% 20% 3	627
September	1st to 10th	Night	9% 4 24% 38% 21% 3	570
	11th to 20th	Night	11% 3 31% 38% 15% 2	570
	21st to end	Night	11% 7% 33% 34% 14% 1	570
October	1st to 10th	Night	14% 8% 33% 31% 12% 2	747
	11th to 20th	Night	18% 11% 39% 26% 7%	760
	21st to end	Night	20% 13% 32% 26% 8%	836
November	1st to 10th	Night	13% 12% 38% 29% 8%	904
	11th to 20th	Night	14% 17% 41% 22% 5%	1000
	21st to end	Night	16% 13% 38% 25% 7% 1	1000
December	1st to 10th	Night	14% 13% 42% 25% 5%	950
	11th to 20th	Night	15% 11% 42% 26% 5% 1	950
	21st to end	Night	19% 14% 39% 24% 3	1045

Page generated at 2024-11-27 16:30:50. Version ac07

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