Turtle Beach Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Turtle Beach Observatory clear sky chart from 2005-11-06 to 2024-10-24.

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	13% 7% 2 6% 5% 4 4 4 6% 7% 42%	100850
	Night	13% 7% 2 5% 4 4 4 3 5% 7% 46%	97988
Transparency	Day	22% 49% 6% 11% 10% 2	100657
	Night	20% 49% 6% 11% 10% 3	97852
Seeing	Day	13% 8% 20% 25% 24% 9%	14993
	Night	15% 8% 25% 31% 19% 3	24755

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	20% 9% 2 6% 3 3 3 3 4 5% 40%	2847
	11th to 20th	Day	21% 6% 2 4 3 2 2 3 3 5% 48%	2850
	21st to end	Day	22% 9% 2 6% 3 3 3 2 4 5% 41%	3135
February	1st to 10th	Day	20% 10% 3 6% 4 4 4 3 4 5% 38%	1710
	11th to 20th	Day	21% 9% 3 6% 4 3 3 2 3 5% 41%	1859
	21st to end	Day	20% 9% 2 7% 5% 4 3 4 4 5% 38%	1727
March	1st to 10th	Day	20% 12% 4 9% 5% 4 4 3 4 5% 31%	3436
	11th to 20th	Day	18% 8% 3 7% 5% 4 4 4 6% 8% 34%	3480
	21st to end	Day	16% 10% 4 7% 5% 4 3 3 3 4 41%	3814
April	1st to 10th	Day	12% 7% 3 7% 4 4 5% 4 6% 6% 41%	2180
	11th to 20th	Day	16% 7% 3 6% 4 4 4 3 5% 8% 39%	2254
	21st to end	Day	10% 5% 3 6% 5% 5% 5% 4 5% 7% 44%	2280
May	1st to 10th	Day	16% 8% 3 8% 6% 5% 5% 4 6% 7% 32%	3765
	11th to 20th	Day	12% 6% 3 6% 4 4 4 3 5% 7% 45%	3948
	21st to end	Day	9% 6% 2 7% 6% 6% 6% 5% 7% 10% 36%	4477
June	1st to 10th	Day	7% 5% 2 7% 6% 6% 6% 5% 8% 10% 38%	2470
	11th to 20th	Day	5% 5% 2 6% 6% 6% 6% 5% 7% 11% 41%	2470
	21st to end	Day	6% 5% 2 6% 6% 6% 6% 5% 8% 10% 38%	2470
July	1st to 10th	Day	8% 6% 2 8% 6% 6% 6% 6% 8% 12% 34%	4120
	11th to 20th	Day	6% 6% 3 8% 7% 6% 7% 6% 8% 10% 33%	4120
	21st to end	Day	15% 9% 3 8% 6% 5% 5% 5% 6% 8% 29%	4465
August	1st to 10th	Day	2 2 1 3 3 4 4 4 6% 9% 63%	4104
	11th to 20th	Day	3 3 1 4 4 3 4 4 7% 10% 56%	3729
	21st to end	Day	9% 5% 2 7% 5% 6% 5% 5% 7% 9% 39%	4180
September	1st to 10th	Day	9% 5% 2 7% 6% 5% 5% 5% 5% 8% 43%	2280
	11th to 20th	Day	13% 6% 3 5% 5% 5% 5% 4 7% 7% 41%	2127
	21st to end	Day	9% 4 1 5% 4 4 4 4 5% 8% 52%	2048
October	1st to 10th	Day	6% 4 1 5% 3 4 4 3 4 5% 62%	1900
	11th to 20th	Day	11% 5% 2 4 3 3 3 2 4 6% 56%	1900
	21st to end	Day	14% 5% 2 4 3 3 4 2 3 6% 53%	2010
November	1st to 10th	Day	10% 5% 2 5% 3 4 4 3 5% 6% 52%	1858
	11th to 20th	Day	11% 6% 2 7% 4 3 3 2 5% 5% 51%	1900
	21st to end	Day	17% 7% 2 7% 4 3 4 3 4 5% 44%	1900
December	1st to 10th	Day	16% 10% 2 5% 4 3 4 3 4 5% 44%	1741
	11th to 20th	Day	16% 11% 3 7% 5% 4 4 3 5% 4 39%	2161
	21st to end	Day	16% 10% 3 7% 4 3 4 3 4 5% 41%	3135
January	1st to 10th	Night	15% 8% 3 5% 3 3 3 2 4 5% 48%	4108
	11th to 20th	Night	19% 7% 2 5% 3 2 3 2 3 4 50%	4120
	21st to end	Night	24% 10% 2 5% 3 2 3 2 3 4 40%	4532
February	1st to 10th	Night	17% 8% 2 7% 3 3 4 3 5% 6% 42%	2470
	11th to 20th	Night	20% 9% 2 4 4 2 3 3 4 5% 43%	2221
	21st to end	Night	22% 8% 3 6% 4 3 3 2 4 4 40%	1727
March	1st to 10th	Night	24% 11% 2 6% 4 4 4 3 5% 6% 32%	3419
	11th to 20th	Night	20% 8% 2 7% 5% 5% 4 3 5% 6% 35%	3480
	21st to end	Night	13% 7% 3 7% 5% 4 4 4 6% 6% 42%	3817
April	1st to 10th	Night	12% 6% 2 5% 5% 4 5% 4 6% 7% 45%	1999
	11th to 20th	Night	15% 6% 2 6% 4 4 4 4 4 7% 44%	1875
	21st to end	Night	11% 5% 2 5% 4 4 5% 4 5% 5% 50%	1900
May	1st to 10th	Night	15% 9% 3 7% 5% 4 4 4 6% 8% 35%	3130
	11th to 20th	Night	15% 6% 2 7% 4 4 4 3 5% 6% 43%	2948
	21st to end	Night	10% 6% 2 7% 6% 4 5% 4 6% 11% 38%	3090
June	1st to 10th	Night	6% 4 2 5% 5% 5% 5% 4 7% 10% 47%	1710
	11th to 20th	Night	4 3 1 4 3 3 3 5% 6% 11% 57%	1710
	21st to end	Night	6% 4 1 3 3 4 4 5% 9% 11% 49%	1710
July	1st to 10th	Night	6% 6% 3 6% 6% 4 5% 4 8% 12% 40%	2850
	11th to 20th	Night	4 4 2 7% 5% 6% 7% 6% 8% 12% 39%	2850
	21st to end	Night	13% 9% 3 7% 5% 3 5% 4 6% 10% 36%	3098
August	1st to 10th	Night	1 2 1 3 2 2 2 2 5% 11% 70%	2836
	11th to 20th	Night	3 2 1 3 3 4 4 5% 8% 13% 56%	3098
	21st to end	Night	7% 5% 3 7% 5% 6% 5% 4 7% 8% 43%	3476
September	1st to 10th	Night	7% 5% 2 6% 5% 4 5% 4 6% 8% 49%	1900
	11th to 20th	Night	11% 5% 2 6% 4 5% 5% 4 5% 8% 45%	2047
	21st to end	Night	8% 5% 2 4 3 3 3 3 5% 6% 58%	2110
October	1st to 10th	Night	6% 3 1 4 3 4 4 3 5% 7% 60%	2280
	11th to 20th	Night	9% 5% 2 3 3 3 3 3 4 6% 59%	2280
	21st to end	Night	13% 5% 2 4 3 2 3 2 4 4 59%	2413
November	1st to 10th	Night	11% 4 1 5% 4 3 3 3 4 5% 57%	2220
	11th to 20th	Night	11% 5% 2 4 5% 4 3 3 4 6% 53%	2280
	21st to end	Night	15% 7% 3 6% 4 4 3 3 5% 6% 45%	2280
December	1st to 10th	Night	19% 8% 3 5% 3 3 3 3 5% 6% 42%	2436
	11th to 20th	Night	15% 9% 3 6% 4 4 3 3 4 5% 45%	3036
	21st to end	Night	16% 9% 2 6% 3 3 3 3 4 5% 44%	4532

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	32% 38% 2 12% 14% 2	2848
	11th to 20th	Day	24% 37% 3 16% 17% 2	2850
	21st to end	Day	29% 40% 2 10% 15% 4	3135
February	1st to 10th	Day	19% 65% 2 5% 6% 4	1710
	11th to 20th	Day	19% 63% 3 7% 6% 2	1868
	21st to end	Day	21% 65% 2 2 6% 5%	1727
March	1st to 10th	Day	39% 42% 4 7% 8% 1	3436
	11th to 20th	Day	29% 42% 5% 15% 7% 2	3480
	21st to end	Day	30% 40% 5% 10% 14% 1	3814
April	1st to 10th	Day	16% 65% 3 6% 7% 3	2180
	11th to 20th	Day	18% 66% 4 5% 4 3	2254
	21st to end	Day	12% 66% 4 8% 8% 2	2280
May	1st to 10th	Day	31% 44% 6% 12% 5% 2	3800
	11th to 20th	Day	23% 41% 5% 11% 17% 1	3952
	21st to end	Day	23% 44% 10% 15% 6% 1	4489
June	1st to 10th	Day	12% 65% 5% 8% 9%	2470
	11th to 20th	Day	15% 66% 7% 6% 4 1	2470
	21st to end	Day	15% 64% 7% 10% 4	2470
July	1st to 10th	Day	25% 41% 18% 14% 2	4056
	11th to 20th	Day	28% 39% 11% 16% 6%	4051
	21st to end	Day	35% 37% 8% 15% 5%	4325
August	1st to 10th	Day	6% 37% 9% 23% 24% 1	4090
	11th to 20th	Day	9% 38% 16% 31% 5% 1	3765
	21st to end	Day	24% 39% 10% 11% 15%	4179
September	1st to 10th	Day	12% 62% 8% 8% 8% 3	2280
	11th to 20th	Day	14% 61% 6% 9% 8% 2	2127
	21st to end	Day	13% 61% 6% 11% 6% 2	2048
October	1st to 10th	Day	10% 60% 5% 10% 9% 6%	1900
	11th to 20th	Day	11% 59% 3 9% 11% 7%	1900
	21st to end	Day	16% 61% 1 4 12% 6%	2010
November	1st to 10th	Day	17% 60% 5% 6% 8% 4	1858
	11th to 20th	Day	16% 60% 3 7% 10% 4	1900
	21st to end	Day	17% 60% 3 9% 9% 3	1900
December	1st to 10th	Day	17% 60% 4 7% 8% 4	1741
	11th to 20th	Day	21% 48% 3 8% 15% 5%	2159
	21st to end	Day	31% 37% 3 6% 18% 4	3135
January	1st to 10th	Night	26% 38% 3 12% 19% 3	4108
	11th to 20th	Night	25% 37% 3 15% 16% 5%	4120
	21st to end	Night	31% 39% 4 11% 11% 4	4532
February	1st to 10th	Night	17% 65% 2 6% 6% 4	2470
	11th to 20th	Night	16% 63% 4 7% 8% 3	2222
	21st to end	Night	19% 64% 2 4 5% 5%	1727
March	1st to 10th	Night	38% 42% 4 8% 7% 1	3419
	11th to 20th	Night	32% 42% 5% 9% 11% 1	3480
	21st to end	Night	25% 42% 5% 10% 16% 2	3817
April	1st to 10th	Night	14% 65% 3 6% 7% 5%	1999
	11th to 20th	Night	16% 67% 3 6% 5% 3	1875
	21st to end	Night	12% 66% 3 7% 9% 3	1900
May	1st to 10th	Night	29% 44% 6% 11% 7% 3	3160
	11th to 20th	Night	27% 42% 5% 10% 14% 2	2949
	21st to end	Night	25% 45% 11% 14% 5% 1	3099
June	1st to 10th	Night	9% 66% 5% 10% 9%	1710
	11th to 20th	Night	9% 67% 9% 10% 4 1	1710
	21st to end	Night	11% 65% 8% 13% 3	1710
July	1st to 10th	Night	21% 41% 21% 14% 3	2805
	11th to 20th	Night	23% 41% 14% 18% 4	2796
	21st to end	Night	32% 37% 11% 14% 5% 1	2999
August	1st to 10th	Night	5% 37% 9% 22% 26% 1	2826
	11th to 20th	Night	7% 39% 19% 30% 4 1	3128
	21st to end	Night	24% 40% 9% 12% 13% 1	3476
September	1st to 10th	Night	11% 62% 7% 10% 7% 4	1900
	11th to 20th	Night	13% 61% 6% 10% 8% 2	2047
	21st to end	Night	12% 62% 6% 11% 7% 2	2110
October	1st to 10th	Night	9% 61% 6% 12% 7% 6%	2280
	11th to 20th	Night	9% 60% 3 10% 12% 7%	2280
	21st to end	Night	14% 61% 3 5% 10% 7%	2413
November	1st to 10th	Night	18% 59% 5% 6% 8% 4	2220
	11th to 20th	Night	17% 60% 3 7% 9% 4	2280
	21st to end	Night	17% 59% 3 8% 10% 4	2280
December	1st to 10th	Night	19% 59% 3 8% 8% 3	2436
	11th to 20th	Night	18% 49% 2 6% 16% 9%	3037
	21st to end	Night	27% 38% 4 10% 17% 4	4532

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	24% 16% 39% 16% 5%	270
	11th to 20th	Day	24% 17% 31% 23% 4	270
	21st to end	Day	22% 22% 33% 19% 3	297
February	1st to 10th	Day	26% 16% 34% 20% 3 1	270
	11th to 20th	Day	33% 17% 32% 17% 1	270
	21st to end	Day	28% 28% 33% 10% 1	225
March	1st to 10th	Day	25% 18% 32% 19% 6%	270
	11th to 20th	Day	18% 23% 37% 18% 4	270
	21st to end	Day	18% 17% 41% 20% 4	297
April	1st to 10th	Day	15% 18% 37% 23% 7%	360
	11th to 20th	Day	23% 16% 27% 23% 10% 2	452
	21st to end	Day	13% 13% 31% 30% 11% 2	460
May	1st to 10th	Day	16% 10% 34% 27% 12% 1	463
	11th to 20th	Day	13% 5% 23% 34% 20% 4	593
	21st to end	Day	9% 5% 25% 35% 19% 7%	734
June	1st to 10th	Day	8% 3 15% 31% 32% 11%	680
	11th to 20th	Day	8% 2 14% 34% 35% 8%	680
	21st to end	Day	9% 2 11% 25% 38% 15%	680
July	1st to 10th	Day	7% 2 7% 25% 43% 15%	671
	11th to 20th	Day	4 2 6% 23% 44% 21%	668
	21st to end	Day	9% 1 6% 25% 45% 15%	739
August	1st to 10th	Day	4 1 6% 19% 49% 21%	676
	11th to 20th	Day	5% 2 3 17% 49% 24%	479
	21st to end	Day	11% 3 7% 19% 32% 28%	539
September	1st to 10th	Day	9% 1 8% 19% 41% 21%	490
	11th to 20th	Day	10% 3 10% 23% 35% 20%	337
	21st to end	Day	13% 4 8% 25% 37% 13%	300
October	1st to 10th	Day	7% 3 19% 37% 26% 9%	300
	11th to 20th	Day	9% 6% 27% 30% 21% 7%	300
	21st to end	Day	21% 12% 22% 23% 16% 5%	306
November	1st to 10th	Day	13% 8% 24% 33% 18% 4	270
	11th to 20th	Day	14% 12% 33% 27% 12% 2	270
	21st to end	Day	21% 15% 34% 21% 6% 2	270
December	1st to 10th	Day	19% 9% 37% 23% 9% 4	270
	11th to 20th	Day	22% 13% 33% 25% 6%	270
	21st to end	Day	23% 15% 35% 22% 3 1	297
January	1st to 10th	Night	21% 12% 37% 24% 6%	950
	11th to 20th	Night	23% 14% 30% 25% 7%	950
	21st to end	Night	23% 12% 35% 27% 3	1045
February	1st to 10th	Night	21% 15% 35% 25% 3	950
	11th to 20th	Night	25% 14% 33% 23% 4	746
	21st to end	Night	26% 17% 36% 20% 1	471
March	1st to 10th	Night	23% 11% 32% 29% 5%	570
	11th to 20th	Night	19% 12% 36% 26% 5% 1	570
	21st to end	Night	15% 11% 38% 28% 8%	627
April	1st to 10th	Night	14% 11% 41% 28% 6%	570
	11th to 20th	Night	17% 12% 36% 24% 12%	563
	21st to end	Night	13% 10% 37% 28% 11% 1	570
May	1st to 10th	Night	12% 9% 32% 35% 11% 1	570
	11th to 20th	Night	12% 5% 27% 35% 18% 3	561
	21st to end	Night	7% 3 25% 39% 20% 5%	617
June	1st to 10th	Night	6% 2 14% 39% 35% 4	570
	11th to 20th	Night	4 3 15% 48% 28% 3	570
	21st to end	Night	8% 1 10% 37% 36% 8%	570
July	1st to 10th	Night	4 3 7% 38% 41% 8%	555
	11th to 20th	Night	3 1 7% 35% 44% 10%	552
	21st to end	Night	5% 1 6% 37% 42% 8%	624
August	1st to 10th	Night	2 1 5% 35% 48% 8%	567
	11th to 20th	Night	5% 6% 33% 47% 9%	564
	21st to end	Night	10% 2 6% 29% 42% 12%	627
September	1st to 10th	Night	7% 2 5% 32% 44% 9%	570
	11th to 20th	Night	13% 1 10% 29% 39% 8%	570
	21st to end	Night	10% 2 12% 34% 35% 8%	590
October	1st to 10th	Night	7% 2 15% 38% 33% 5%	760
	11th to 20th	Night	11% 7% 21% 39% 19% 3	760
	21st to end	Night	15% 7% 23% 33% 19% 2	805
November	1st to 10th	Night	12% 5% 27% 34% 21% 1	740
	11th to 20th	Night	13% 9% 28% 35% 14%	760
	21st to end	Night	19% 9% 31% 28% 12% 1	760
December	1st to 10th	Night	22% 13% 28% 28% 9%	916
	11th to 20th	Night	24% 11% 31% 29% 5%	950
	21st to end	Night	23% 12% 31% 28% 6%	1045

Page generated at 2024-10-21 01:20:06. Version ac07

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