Mother Neff State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mother Neff State Park clear sky chart from 2005-11-06 to 2025-09-19.

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% 5% 2 5% 4 4 4 3 5% 7% 50%	126250
	Night	12% 5% 2 4 3 3 3 3 5% 7% 53%	123106
Transparency	Day	33% 5% 9% 22% 21% 10%	129993
	Night	31% 5% 9% 21% 22% 13%	127426
Seeing	Day	12% 7% 23% 29% 23% 7%	16183
	Night	13% 7% 27% 35% 16% 1	25994

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	14% 8% 2 5% 3 3 2 2 5% 6% 51%	4077
	11th to 20th	Day	13% 5% 1 4 2 2 2 2 4 7% 59%	4080
	21st to end	Day	23% 8% 3 6% 3 2 2 2 2 4 45%	4557
February	1st to 10th	Day	18% 7% 1 6% 3 2 2 3 3 6% 48%	2000
	11th to 20th	Day	16% 9% 3 5% 3 3 3 3 3 5% 46%	1949
	21st to end	Day	18% 7% 2 4 3 3 3 2 3 5% 50%	1654
March	1st to 10th	Day	13% 7% 2 6% 4 3 3 3 5% 5% 49%	4936
	11th to 20th	Day	13% 5% 2 5% 4 3 3 3 4 6% 52%	4980
	21st to end	Day	12% 6% 2 6% 4 4 4 3 6% 7% 47%	5462
April	1st to 10th	Day	14% 8% 3 5% 4 3 3 3 6% 7% 44%	2200
	11th to 20th	Day	15% 7% 2 7% 4 4 3 4 4 7% 43%	2206
	21st to end	Day	14% 5% 2 6% 4 4 4 3 5% 5% 49%	2559
May	1st to 10th	Day	17% 7% 3 6% 4 4 4 4 6% 7% 37%	5862
	11th to 20th	Day	12% 6% 3 7% 4 4 4 4 5% 7% 44%	5862
	21st to end	Day	12% 7% 3 7% 5% 5% 6% 5% 8% 9% 35%	6434
June	1st to 10th	Day	5% 4 2 5% 4 5% 4 4 6% 8% 53%	2600
	11th to 20th	Day	6% 3 1 5% 5% 4 5% 3 6% 9% 52%	2600
	21st to end	Day	5% 4 2 4 5% 5% 5% 5% 7% 9% 49%	2600
July	1st to 10th	Day	8% 6% 3 7% 5% 5% 5% 4 6% 8% 42%	5900
	11th to 20th	Day	4 3 1 4 4 3 5% 4 6% 10% 55%	5900
	21st to end	Day	5% 5% 2 5% 4 4 5% 4 7% 10% 48%	6422
August	1st to 10th	Day	1 1 1 2 2 3 3 2 5% 7% 73%	4234
	11th to 20th	Day	4 1 1 3 2 3 3 3 5% 9% 67%	4076
	21st to end	Day	4 2 1 3 4 4 5% 4 7% 10% 54%	4090
September	1st to 10th	Day	9% 4 1 6% 5% 5% 5% 3 5% 7% 50%	2200
	11th to 20th	Day	9% 4 2 6% 4 4 4 4 6% 7% 48%	2178
	21st to end	Day	7% 4 2 6% 3 4 4 4 5% 7% 56%	2090
October	1st to 10th	Day	5% 4 2 3 3 3 4 3 5% 7% 62%	2090
	11th to 20th	Day	12% 4 2 4 3 3 3 2 4 4 60%	1905
	21st to end	Day	13% 4 1 4 2 3 3 2 3 4 61%	2090
November	1st to 10th	Day	14% 6% 2 5% 3 3 4 2 4 5% 52%	1958
	11th to 20th	Day	9% 5% 2 4 3 3 4 4 4 6% 56%	1880
	21st to end	Day	17% 6% 2 5% 4 3 3 2 3 6% 49%	1800
December	1st to 10th	Day	19% 6% 2 4 3 4 3 3 5% 5% 46%	2940
	11th to 20th	Day	16% 7% 3 6% 4 4 4 3 5% 5% 44%	3391
	21st to end	Day	16% 5% 2 4 3 3 2 2 3 5% 55%	4488
January	1st to 10th	Night	16% 6% 2 4 2 2 2 2 3 4 56%	5888
	11th to 20th	Night	10% 4 1 3 2 1 1 1 3 6% 67%	5900
	21st to end	Night	26% 6% 2 5% 3 3 2 2 3 5% 42%	6462
February	1st to 10th	Night	16% 7% 3 5% 2 3 3 2 4 4 51%	2400
	11th to 20th	Night	18% 7% 2 5% 2 3 3 3 3 6% 49%	2338
	21st to end	Night	19% 5% 2 3 3 3 3 2 4 5% 50%	1975
March	1st to 10th	Night	13% 7% 2 6% 4 4 4 3 5% 6% 46%	4919
	11th to 20th	Night	12% 5% 2 4 4 3 3 3 5% 7% 51%	4980
	21st to end	Night	13% 8% 2 6% 4 3 3 3 4 6% 48%	5467
April	1st to 10th	Night	10% 5% 2 5% 4 3 3 4 5% 6% 52%	2200
	11th to 20th	Night	14% 5% 2 6% 4 4 4 3 6% 6% 47%	2140
	21st to end	Night	13% 6% 2 5% 4 3 3 3 6% 6% 50%	1836
May	1st to 10th	Night	19% 8% 2 5% 4 4 3 3 6% 6% 40%	4053
	11th to 20th	Night	9% 6% 2 7% 5% 4 5% 4 6% 6% 46%	4053
	21st to end	Night	11% 6% 2 6% 4 4 5% 4 6% 9% 43%	4443
June	1st to 10th	Night	4 3 1 3 3 4 3 3 6% 11% 59%	1800
	11th to 20th	Night	4 3 1 3 4 3 4 3 6% 9% 60%	1800
	21st to end	Night	4 3 2 4 4 4 4 3 5% 11% 57%	1800
July	1st to 10th	Night	8% 5% 2 5% 4 4 5% 4 7% 9% 46%	4078
	11th to 20th	Night	2 2 1 3 3 3 3 3 6% 10% 63%	4077
	21st to end	Night	4 4 2 4 4 4 4 4 7% 10% 53%	4449
August	1st to 10th	Night	1 1 1 1 2 2 2 4 6% 80%	2926
	11th to 20th	Night	4 2 1 3 2 2 3 3 6% 10% 63%	2978
	21st to end	Night	3 2 1 3 3 3 4 3 6% 11% 60%	3811
September	1st to 10th	Night	8% 4 1 4 4 4 5% 4 6% 7% 53%	2200
	11th to 20th	Night	9% 5% 1 5% 4 4 5% 4 5% 7% 51%	2178
	21st to end	Night	7% 3 1 4 2 3 3 4 5% 6% 62%	2090
October	1st to 10th	Night	6% 3 1 3 3 3 2 3 4 6% 67%	2090
	11th to 20th	Night	11% 3 1 3 2 3 3 3 5% 5% 61%	2256
	21st to end	Night	13% 4 2 4 3 2 2 2 3 4 61%	2508
November	1st to 10th	Night	13% 5% 2 5% 3 3 2 3 3 5% 57%	2340
	11th to 20th	Night	8% 5% 2 5% 4 3 3 3 4 5% 58%	2515
	21st to end	Night	16% 5% 2 5% 4 2 3 3 4 5% 51%	2600
December	1st to 10th	Night	19% 5% 2 5% 3 3 3 3 4 6% 47%	4250
	11th to 20th	Night	18% 7% 2 6% 3 3 3 2 3 4 48%	4816
	21st to end	Night	15% 7% 2 4 2 2 2 2 3 3 57%	6490

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	36% 4 5% 24% 22% 9%	4078
	11th to 20th	Day	28% 3 4 21% 28% 17%	4080
	21st to end	Day	48% 2 3 11% 22% 15%	4557
February	1st to 10th	Day	41% 3 5% 15% 22% 14%	2000
	11th to 20th	Day	42% 3 6% 18% 20% 11%	1959
	21st to end	Day	39% 3 4 16% 21% 17%	1654
March	1st to 10th	Day	37% 4 4 17% 20% 18%	4936
	11th to 20th	Day	35% 5% 7% 10% 16% 27%	4980
	21st to end	Day	37% 5% 8% 22% 21% 7%	5464
April	1st to 10th	Day	40% 5% 8% 17% 17% 13%	2200
	11th to 20th	Day	42% 5% 7% 17% 19% 11%	2206
	21st to end	Day	38% 5% 6% 19% 24% 8%	2559
May	1st to 10th	Day	45% 6% 10% 20% 15% 3	5900
	11th to 20th	Day	40% 6% 8% 16% 25% 6%	5866
	21st to end	Day	42% 8% 10% 21% 14% 4	6447
June	1st to 10th	Day	28% 7% 13% 27% 22% 4	2600
	11th to 20th	Day	28% 6% 12% 28% 19% 7%	2600
	21st to end	Day	31% 8% 12% 25% 21% 4	2600
July	1st to 10th	Day	38% 8% 19% 28% 8% 1	5836
	11th to 20th	Day	23% 7% 15% 34% 17% 3	5831
	21st to end	Day	29% 8% 15% 28% 18% 2	6240
August	1st to 10th	Day	11% 4 11% 38% 35% 2	4220
	11th to 20th	Day	15% 5% 19% 42% 17% 2	4115
	21st to end	Day	21% 11% 19% 28% 18% 3	4089
September	1st to 10th	Day	33% 6% 10% 21% 19% 11%	2200
	11th to 20th	Day	35% 6% 11% 21% 20% 6%	2178
	21st to end	Day	28% 5% 8% 23% 22% 14%	2090
October	1st to 10th	Day	14% 3 6% 13% 25% 38%	3480
	11th to 20th	Day	18% 2 6% 17% 35% 22%	3145
	21st to end	Day	23% 3 5% 22% 35% 12%	3428
November	1st to 10th	Day	36% 5% 8% 19% 22% 10%	1958
	11th to 20th	Day	30% 4 9% 18% 24% 16%	1880
	21st to end	Day	39% 4 4 19% 21% 13%	1800
December	1st to 10th	Day	41% 4 7% 18% 21% 9%	2940
	11th to 20th	Day	43% 4 6% 11% 24% 12%	3389
	21st to end	Day	34% 3 4 18% 27% 14%	4488
January	1st to 10th	Night	35% 3 3 22% 27% 11%	5888
	11th to 20th	Night	23% 1 4 18% 34% 20%	5900
	21st to end	Night	47% 3 3 12% 20% 16%	6462
February	1st to 10th	Night	38% 3 6% 13% 23% 17%	2400
	11th to 20th	Night	40% 3 5% 17% 21% 13%	2338
	21st to end	Night	38% 3 6% 15% 20% 17%	1975
March	1st to 10th	Night	38% 5% 5% 13% 22% 16%	4919
	11th to 20th	Night	33% 6% 8% 13% 16% 24%	4980
	21st to end	Night	38% 5% 7% 17% 23% 10%	5467
April	1st to 10th	Night	33% 6% 10% 19% 17% 16%	2200
	11th to 20th	Night	37% 5% 9% 16% 19% 14%	2140
	21st to end	Night	36% 5% 10% 18% 23% 9%	1836
May	1st to 10th	Night	44% 5% 9% 22% 15% 5%	4080
	11th to 20th	Night	35% 7% 11% 19% 20% 8%	4054
	21st to end	Night	37% 8% 12% 26% 11% 6%	4452
June	1st to 10th	Night	21% 8% 16% 31% 22% 4	1800
	11th to 20th	Night	19% 7% 15% 32% 21% 7%	1800
	21st to end	Night	24% 7% 13% 27% 24% 5%	1800
July	1st to 10th	Night	32% 8% 21% 32% 6% 1	4035
	11th to 20th	Night	17% 6% 21% 37% 17% 1	4026
	21st to end	Night	24% 9% 20% 29% 15% 4	4320
August	1st to 10th	Night	6% 5% 11% 39% 36% 3	2916
	11th to 20th	Night	17% 5% 22% 37% 17% 2	3005
	21st to end	Night	18% 9% 22% 31% 17% 3	3811
September	1st to 10th	Night	29% 7% 12% 23% 18% 11%	2200
	11th to 20th	Night	33% 6% 13% 21% 18% 8%	2178
	21st to end	Night	22% 6% 11% 24% 22% 15%	2090
October	1st to 10th	Night	14% 3 6% 15% 21% 42%	3480
	11th to 20th	Night	16% 3 6% 16% 33% 26%	3742
	21st to end	Night	23% 3 4 19% 34% 17%	4120
November	1st to 10th	Night	32% 4 6% 20% 24% 14%	2340
	11th to 20th	Night	28% 5% 7% 17% 25% 18%	2515
	21st to end	Night	37% 3 7% 17% 22% 14%	2600
December	1st to 10th	Night	40% 3 5% 20% 22% 10%	4250
	11th to 20th	Night	42% 3 5% 10% 25% 15%	4817
	21st to end	Night	33% 3 4 16% 28% 17%	6490

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% 39% 23% 6% 1	300
	11th to 20th	Day	20% 13% 33% 26% 7% 1	300
	21st to end	Day	21% 12% 38% 21% 8%	330
February	1st to 10th	Day	24% 15% 33% 22% 7%	300
	11th to 20th	Day	23% 17% 38% 18% 4	300
	21st to end	Day	26% 14% 39% 19% 2	249
March	1st to 10th	Day	23% 16% 37% 20% 3	300
	11th to 20th	Day	18% 19% 38% 20% 4 1	300
	21st to end	Day	18% 13% 45% 17% 7% 1	330
April	1st to 10th	Day	20% 16% 40% 19% 5%	300
	11th to 20th	Day	19% 13% 38% 21% 6% 1	324
	21st to end	Day	17% 12% 38% 25% 8% 1	659
May	1st to 10th	Day	15% 12% 35% 29% 9%	703
	11th to 20th	Day	17% 6% 30% 31% 14% 2	725
	21st to end	Day	14% 6% 30% 31% 17% 3	789
June	1st to 10th	Day	6% 2 19% 41% 22% 10%	730
	11th to 20th	Day	6% 2 19% 43% 27% 3	730
	21st to end	Day	6% 2 12% 37% 32% 11%	730
July	1st to 10th	Day	7% 2 10% 31% 36% 13%	721
	11th to 20th	Day	2 1 6% 36% 44% 11%	718
	21st to end	Day	4 1 5% 33% 42% 15%	794
August	1st to 10th	Day	2 1 5% 27% 48% 17%	726
	11th to 20th	Day	6% 3 32% 45% 14%	659
	21st to end	Day	5% 1 4 23% 41% 27%	452
September	1st to 10th	Day	7% 1 6% 24% 37% 25%	330
	11th to 20th	Day	5% 6% 22% 47% 20%	324
	21st to end	Day	9% 2 9% 28% 35% 17%	300
October	1st to 10th	Day	3 3 12% 31% 40% 12%	300
	11th to 20th	Day	11% 5% 22% 32% 25% 7%	300
	21st to end	Day	20% 10% 25% 20% 21% 3	330
November	1st to 10th	Day	19% 7% 29% 30% 11% 5%	300
	11th to 20th	Day	15% 9% 29% 26% 17% 4	300
	21st to end	Day	19% 14% 33% 22% 10% 2	300
December	1st to 10th	Day	17% 8% 31% 27% 12% 4	300
	11th to 20th	Day	19% 13% 35% 24% 8% 1	300
	21st to end	Day	20% 8% 37% 25% 9% 1	330
January	1st to 10th	Night	18% 9% 35% 29% 8% 1	1000
	11th to 20th	Night	20% 12% 32% 30% 7% 1	1000
	21st to end	Night	18% 10% 34% 32% 6%	1085
February	1st to 10th	Night	21% 13% 34% 28% 5%	800
	11th to 20th	Night	22% 12% 38% 24% 3	784
	21st to end	Night	21% 13% 43% 19% 3	655
March	1st to 10th	Night	20% 14% 36% 27% 4	600
	11th to 20th	Night	17% 10% 39% 29% 5%	600
	21st to end	Night	14% 14% 42% 26% 4	660
April	1st to 10th	Night	12% 12% 43% 31% 3	600
	11th to 20th	Night	15% 14% 38% 27% 6%	593
	21st to end	Night	15% 10% 41% 27% 8%	600
May	1st to 10th	Night	12% 10% 42% 30% 6%	600
	11th to 20th	Night	12% 7% 36% 31% 13% 1	591
	21st to end	Night	10% 5% 31% 38% 14% 1	650
June	1st to 10th	Night	4 3 23% 45% 23% 2	600
	11th to 20th	Night	5% 2 28% 49% 16% 1	600
	21st to end	Night	3 1 16% 48% 28% 4	600
July	1st to 10th	Night	6% 1 11% 45% 32% 4	585
	11th to 20th	Night	3 1 9% 53% 32% 2	582
	21st to end	Night	2 1 7% 49% 38% 3	657
August	1st to 10th	Night	2 3 55% 36% 5%	597
	11th to 20th	Night	7% 1 7% 44% 37% 5%	594
	21st to end	Night	4 1 5% 41% 44% 5%	660
September	1st to 10th	Night	9% 2 8% 40% 37% 5%	600
	11th to 20th	Night	9% 2 8% 38% 39% 4	594
	21st to end	Night	8% 1 11% 40% 36% 4	570
October	1st to 10th	Night	7% 1 11% 50% 26% 5%	570
	11th to 20th	Night	13% 4 24% 38% 19% 2	736
	21st to end	Night	14% 9% 26% 32% 18% 1	836
November	1st to 10th	Night	14% 4 27% 39% 16% 1	780
	11th to 20th	Night	10% 8% 29% 37% 15% 1	915
	21st to end	Night	19% 9% 31% 30% 11% 1	1000
December	1st to 10th	Night	15% 8% 34% 34% 9%	1000
	11th to 20th	Night	20% 10% 29% 34% 7%	1000
	21st to end	Night	20% 7% 35% 31% 7%	1100

Page generated at 2025-09-16 00:49:13. Version ac07

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