BuckSnort Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the BuckSnort Observatory clear sky chart from 2005-11-06 to 2024-11-25.

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	10% 5% 2 5% 4 3 4 3 5% 7% 52%	101218
	Night	10% 5% 2 4 3 3 3 3 5% 6% 56%	98363
Transparency	Day	30% 5% 10% 22% 23% 10%	105025
	Night	28% 5% 10% 22% 23% 13%	102683
Seeing	Day	12% 7% 21% 29% 24% 8%	15029
	Night	12% 7% 27% 37% 16% 1	24946

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	11% 8% 1 4 2 2 3 2 3 6% 56%	2847
	11th to 20th	Day	14% 5% 2 3 2 2 2 2 5% 6% 58%	2850
	21st to end	Day	17% 6% 2 5% 3 3 3 2 4 5% 50%	3276
February	1st to 10th	Day	16% 6% 2 5% 3 3 3 2 3 6% 51%	1900
	11th to 20th	Day	14% 8% 3 4 2 3 3 3 4 5% 50%	1849
	21st to end	Day	17% 6% 2 3 3 2 3 2 3 5% 54%	1570
March	1st to 10th	Day	14% 7% 2 6% 4 4 4 3 4 6% 46%	3372
	11th to 20th	Day	18% 7% 2 6% 4 4 5% 4 6% 7% 38%	3480
	21st to end	Day	10% 6% 2 6% 4 4 5% 4 6% 7% 46%	3814
April	1st to 10th	Day	12% 8% 2 5% 4 3 4 3 5% 7% 47%	2090
	11th to 20th	Day	15% 6% 2 6% 4 3 3 3 6% 6% 47%	2103
	21st to end	Day	12% 5% 2 5% 4 4 3 3 4 6% 51%	2451
May	1st to 10th	Day	18% 7% 3 6% 4 4 4 3 6% 7% 38%	4082
	11th to 20th	Day	15% 7% 2 6% 3 3 4 3 5% 6% 47%	4082
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 9% 37%	4477
June	1st to 10th	Day	5% 4 1 4 4 5% 4 4 6% 8% 54%	2470
	11th to 20th	Day	5% 3 2 4 4 3 4 5% 6% 10% 53%	2470
	21st to end	Day	7% 3 2 4 5% 4 5% 4 7% 8% 51%	2470
July	1st to 10th	Day	4 3 2 5% 4 5% 5% 5% 6% 8% 53%	4120
	11th to 20th	Day	3 2 1 4 3 3 4 3 5% 8% 63%	4120
	21st to end	Day	6% 5% 2 6% 4 5% 5% 5% 7% 11% 44%	4465
August	1st to 10th	Day	2 1 2 3 3 3 3 5% 7% 72%	4104
	11th to 20th	Day	5% 2 1 3 3 3 3 2 5% 8% 65%	3798
	21st to end	Day	4 3 1 4 4 4 4 4 6% 10% 55%	4034
September	1st to 10th	Day	11% 5% 1 5% 4 4 4 4 5% 6% 51%	2090
	11th to 20th	Day	11% 5% 2 6% 4 4 3 3 5% 7% 51%	2090
	21st to end	Day	7% 3 2 5% 2 3 4 3 6% 7% 57%	2090
October	1st to 10th	Day	5% 4 1 4 3 3 3 4 5% 5% 62%	2090
	11th to 20th	Day	10% 4 1 4 2 2 3 3 3 5% 61%	1949
	21st to end	Day	11% 5% 1 3 3 3 2 2 3 5% 62%	2090
November	1st to 10th	Day	14% 6% 2 5% 3 2 3 3 4 5% 54%	1958
	11th to 20th	Day	7% 5% 2 5% 3 3 3 2 4 6% 60%	1815
	21st to end	Day	15% 6% 2 5% 4 3 3 2 4 5% 52%	1746
December	1st to 10th	Day	13% 6% 2 5% 3 3 4 3 4 5% 52%	1710
	11th to 20th	Day	13% 7% 2 5% 4 4 4 3 5% 6% 48%	2161
	21st to end	Day	14% 6% 2 4 2 2 2 2 3 5% 57%	3135
January	1st to 10th	Night	15% 6% 2 3 2 2 2 2 3 5% 59%	4108
	11th to 20th	Night	12% 4 1 3 2 2 2 1 2 4 66%	4120
	21st to end	Night	17% 7% 2 6% 3 3 3 3 4 5% 47%	4407
February	1st to 10th	Night	13% 7% 3 5% 4 4 2 2 3 5% 53%	2280
	11th to 20th	Night	16% 6% 2 5% 3 2 3 2 4 5% 53%	2218
	21st to end	Night	16% 5% 1 4 3 3 2 3 5% 5% 53%	1884
March	1st to 10th	Night	12% 5% 2 6% 4 4 3 3 5% 6% 50%	3483
	11th to 20th	Night	16% 7% 2 6% 4 4 4 4 6% 7% 41%	3480
	21st to end	Night	10% 6% 2 6% 4 4 5% 3 5% 6% 49%	3817
April	1st to 10th	Night	8% 5% 2 4 5% 4 4 4 5% 6% 53%	2090
	11th to 20th	Night	12% 6% 2 6% 3 4 4 3 4 5% 50%	2021
	21st to end	Night	11% 6% 1 4 3 3 3 3 5% 7% 53%	1729
May	1st to 10th	Night	22% 9% 2 4 3 2 3 3 4 7% 43%	2823
	11th to 20th	Night	9% 7% 2 6% 3 4 4 3 5% 7% 50%	2823
	21st to end	Night	12% 5% 1 5% 3 4 5% 4 7% 8% 47%	3090
June	1st to 10th	Night	3 2 1 3 3 3 3 4 6% 10% 61%	1710
	11th to 20th	Night	5% 2 1 3 3 3 3 4 6% 9% 62%	1710
	21st to end	Night	4 5% 1 3 3 3 3 3 7% 8% 59%	1710
July	1st to 10th	Night	4 2 1 4 3 3 3 3 5% 9% 63%	2850
	11th to 20th	Night	2 2 1 2 2 3 3 3 6% 9% 68%	2850
	21st to end	Night	5% 5% 2 6% 4 4 4 3 6% 9% 53%	3098
August	1st to 10th	Night	1 1 1 1 1 2 2 4 7% 79%	2836
	11th to 20th	Night	3 2 1 3 2 2 3 3 6% 10% 64%	3036
	21st to end	Night	3 2 1 3 3 3 3 3 7% 10% 60%	3626
September	1st to 10th	Night	9% 3 2 4 3 3 5% 3 6% 7% 54%	2090
	11th to 20th	Night	10% 6% 2 4 3 4 3 4 5% 8% 51%	2090
	21st to end	Night	7% 4 1 4 2 3 4 3 5% 7% 61%	2090
October	1st to 10th	Night	5% 3 1 3 2 3 3 3 4 6% 68%	2090
	11th to 20th	Night	10% 4 1 4 3 3 3 3 4 5% 62%	2209
	21st to end	Night	12% 4 2 4 2 3 2 2 3 4 62%	2508
November	1st to 10th	Night	12% 5% 2 5% 3 2 3 2 4 5% 59%	2340
	11th to 20th	Night	6% 5% 2 4 4 3 3 3 5% 5% 60%	2580
	21st to end	Night	15% 5% 2 4 3 3 3 2 4 4 54%	2529
December	1st to 10th	Night	11% 4 2 5% 3 3 3 3 5% 7% 54%	2470
	11th to 20th	Night	12% 7% 3 6% 3 3 3 3 4 5% 50%	3036
	21st to end	Night	16% 5% 2 4 2 2 2 2 3 4 57%	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	31% 4 5% 16% 29% 14%	2848
	11th to 20th	Day	29% 3 6% 17% 30% 14%	2850
	21st to end	Day	38% 4 5% 13% 27% 13%	3276
February	1st to 10th	Day	37% 4 6% 15% 22% 16%	1900
	11th to 20th	Day	37% 4 6% 18% 20% 14%	1859
	21st to end	Day	35% 4 4 15% 24% 18%	1570
March	1st to 10th	Day	38% 6% 6% 13% 23% 14%	3372
	11th to 20th	Day	45% 8% 12% 11% 16% 9%	3480
	21st to end	Day	35% 7% 11% 16% 23% 9%	3814
April	1st to 10th	Day	38% 5% 7% 19% 17% 15%	2090
	11th to 20th	Day	39% 5% 8% 17% 20% 11%	2103
	21st to end	Day	34% 6% 8% 19% 25% 9%	2451
May	1st to 10th	Day	44% 8% 10% 17% 16% 5%	4120
	11th to 20th	Day	38% 6% 8% 18% 26% 4	4086
	21st to end	Day	39% 10% 13% 22% 11% 5%	4489
June	1st to 10th	Day	26% 7% 13% 28% 21% 4	2470
	11th to 20th	Day	26% 6% 14% 29% 18% 7%	2470
	21st to end	Day	29% 7% 13% 23% 23% 5%	2470
July	1st to 10th	Day	28% 6% 18% 37% 10% 1	4056
	11th to 20th	Day	18% 5% 15% 37% 21% 5%	4051
	21st to end	Day	31% 7% 15% 32% 15% 1	4325
August	1st to 10th	Day	13% 4 12% 32% 38% 2	4090
	11th to 20th	Day	18% 5% 16% 40% 19% 3	3836
	21st to end	Day	23% 7% 19% 27% 20% 3	4033
September	1st to 10th	Day	34% 6% 10% 19% 20% 11%	2090
	11th to 20th	Day	34% 5% 11% 21% 22% 6%	2090
	21st to end	Day	26% 6% 9% 21% 22% 15%	2090
October	1st to 10th	Day	13% 4 6% 13% 27% 37%	3480
	11th to 20th	Day	18% 3 7% 18% 33% 23%	3215
	21st to end	Day	22% 4 3 21% 38% 13%	3428
November	1st to 10th	Day	34% 4 8% 18% 25% 11%	1958
	11th to 20th	Day	26% 4 9% 18% 24% 18%	1815
	21st to end	Day	37% 3 5% 18% 22% 15%	1746
December	1st to 10th	Day	34% 3 8% 22% 23% 11%	1710
	11th to 20th	Day	37% 5% 8% 12% 24% 13%	2159
	21st to end	Day	32% 3 5% 16% 28% 16%	3135
January	1st to 10th	Night	30% 3 4 16% 30% 17%	4108
	11th to 20th	Night	25% 2 5% 17% 29% 22%	4120
	21st to end	Night	40% 5% 5% 13% 23% 14%	4407
February	1st to 10th	Night	36% 4 7% 13% 22% 19%	2280
	11th to 20th	Night	35% 3 6% 17% 23% 16%	2218
	21st to end	Night	34% 4 6% 15% 21% 20%	1884
March	1st to 10th	Night	34% 6% 8% 15% 25% 13%	3483
	11th to 20th	Night	41% 8% 11% 15% 16% 9%	3480
	21st to end	Night	34% 7% 10% 18% 23% 8%	3817
April	1st to 10th	Night	31% 6% 9% 20% 18% 16%	2090
	11th to 20th	Night	36% 5% 10% 15% 19% 15%	2021
	21st to end	Night	31% 6% 10% 20% 23% 9%	1729
May	1st to 10th	Night	42% 7% 9% 19% 15% 8%	2850
	11th to 20th	Night	31% 7% 13% 21% 21% 6%	2824
	21st to end	Night	33% 8% 13% 30% 11% 5%	3099
June	1st to 10th	Night	18% 8% 17% 32% 22% 4	1710
	11th to 20th	Night	17% 6% 16% 32% 21% 8%	1710
	21st to end	Night	21% 8% 12% 30% 23% 5%	1710
July	1st to 10th	Night	19% 5% 20% 44% 10% 1	2805
	11th to 20th	Night	14% 4 18% 41% 20% 3	2796
	21st to end	Night	28% 6% 18% 35% 13% 1	2999
August	1st to 10th	Night	7% 3 13% 37% 37% 3	2826
	11th to 20th	Night	16% 4 23% 36% 18% 3	3064
	21st to end	Night	19% 8% 21% 30% 18% 3	3626
September	1st to 10th	Night	28% 7% 13% 23% 19% 11%	2090
	11th to 20th	Night	32% 7% 13% 23% 20% 7%	2090
	21st to end	Night	24% 4 11% 25% 21% 16%	2090
October	1st to 10th	Night	11% 3 6% 16% 21% 43%	3480
	11th to 20th	Night	17% 3 8% 17% 31% 24%	3669
	21st to end	Night	22% 3 4 20% 36% 16%	4120
November	1st to 10th	Night	30% 4 7% 20% 25% 15%	2340
	11th to 20th	Night	26% 4 8% 20% 24% 19%	2580
	21st to end	Night	35% 4 7% 16% 23% 16%	2529
December	1st to 10th	Night	31% 3 10% 20% 24% 12%	2470
	11th to 20th	Night	37% 4 5% 12% 25% 17%	3037
	21st to end	Night	33% 3 4 15% 27% 18%	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	17% 14% 36% 28% 5% 1	270
	11th to 20th	Day	22% 10% 34% 23% 8% 3	270
	21st to end	Day	19% 11% 37% 25% 8%	297
February	1st to 10th	Day	21% 17% 36% 19% 6%	270
	11th to 20th	Day	20% 16% 41% 18% 4	270
	21st to end	Day	20% 20% 36% 22% 1	225
March	1st to 10th	Day	21% 17% 32% 26% 3	270
	11th to 20th	Day	19% 16% 37% 22% 6%	270
	21st to end	Day	14% 15% 42% 23% 6%	297
April	1st to 10th	Day	18% 16% 42% 18% 6%	270
	11th to 20th	Day	14% 13% 44% 20% 7% 1	301
	21st to end	Day	15% 16% 39% 22% 8% 1	631
May	1st to 10th	Day	13% 8% 38% 30% 10%	653
	11th to 20th	Day	17% 7% 28% 33% 12% 3	675
	21st to end	Day	15% 6% 25% 34% 15% 4	734
June	1st to 10th	Day	6% 1 15% 43% 29% 6%	680
	11th to 20th	Day	5% 2 15% 49% 24% 5%	680
	21st to end	Day	5% 2 10% 36% 36% 11%	680
July	1st to 10th	Day	7% 2 7% 33% 38% 14%	671
	11th to 20th	Day	3 4 32% 48% 13%	668
	21st to end	Day	4 1 3 31% 45% 15%	739
August	1st to 10th	Day	2 4 29% 47% 17%	676
	11th to 20th	Day	7% 1 2 33% 42% 15%	525
	21st to end	Day	5% 1 5% 25% 40% 25%	458
September	1st to 10th	Day	12% 5% 16% 42% 25%	300
	11th to 20th	Day	4 1 6% 22% 42% 26%	300
	21st to end	Day	12% 2 4 28% 37% 16%	300
October	1st to 10th	Day	3 2 11% 34% 39% 11%	300
	11th to 20th	Day	9% 3 26% 34% 24% 4	300
	21st to end	Day	18% 10% 23% 23% 22% 4	330
November	1st to 10th	Day	21% 5% 28% 29% 14% 4	300
	11th to 20th	Day	12% 12% 24% 31% 16% 4	300
	21st to end	Day	21% 13% 32% 20% 12% 2	282
December	1st to 10th	Day	16% 8% 33% 27% 13% 4	270
	11th to 20th	Day	17% 13% 39% 21% 9%	270
	21st to end	Day	20% 10% 35% 25% 9% 1	297
January	1st to 10th	Night	16% 9% 37% 31% 7%	950
	11th to 20th	Night	16% 12% 30% 34% 7% 1	950
	21st to end	Night	17% 10% 35% 30% 7%	972
February	1st to 10th	Night	18% 13% 34% 30% 5%	760
	11th to 20th	Night	19% 12% 40% 26% 3	744
	21st to end	Night	21% 11% 43% 21% 3	628
March	1st to 10th	Night	17% 13% 37% 30% 3	612
	11th to 20th	Night	16% 11% 38% 30% 6%	570
	21st to end	Night	10% 11% 47% 29% 3	627
April	1st to 10th	Night	10% 10% 48% 28% 4	570
	11th to 20th	Night	14% 11% 44% 27% 4	563
	21st to end	Night	13% 9% 45% 25% 8%	570
May	1st to 10th	Night	14% 9% 43% 29% 5%	570
	11th to 20th	Night	11% 6% 35% 36% 12%	561
	21st to end	Night	11% 5% 32% 38% 14%	617
June	1st to 10th	Night	3 2 21% 49% 23% 2	570
	11th to 20th	Night	5% 1 24% 52% 17%	570
	21st to end	Night	3 3 15% 48% 29% 2	570
July	1st to 10th	Night	5% 1 9% 50% 31% 4	555
	11th to 20th	Night	3 1 8% 53% 33% 2	552
	21st to end	Night	2 6% 50% 37% 4	624
August	1st to 10th	Night	1 1 4 51% 40% 4	567
	11th to 20th	Night	7% 1 4 45% 39% 4	564
	21st to end	Night	4 3 44% 42% 7%	627
September	1st to 10th	Night	8% 3 8% 39% 36% 6%	570
	11th to 20th	Night	12% 1 5% 39% 39% 3	570
	21st to end	Night	10% 1 9% 40% 37% 3	570
October	1st to 10th	Night	6% 1 14% 48% 29% 3	570
	11th to 20th	Night	11% 4 26% 41% 17% 1	689
	21st to end	Night	14% 7% 28% 33% 17% 1	836
November	1st to 10th	Night	14% 3 23% 44% 15% 1	780
	11th to 20th	Night	9% 7% 30% 38% 15% 1	980
	21st to end	Night	17% 9% 31% 31% 11% 1	973
December	1st to 10th	Night	13% 9% 29% 39% 10% 1	950
	11th to 20th	Night	19% 9% 31% 34% 6%	950
	21st to end	Night	17% 8% 33% 34% 7%	1045

Page generated at 2024-11-22 07:02:30. Version ac07

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