Little Piney Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Piney Observatory clear sky chart from 2005-11-06 to 2025-01-22.

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	15% 6% 2 5% 4 4 4 3 5% 7% 46%	104540
	Night	15% 6% 2 5% 3 3 3 3 5% 6% 49%	104930
Transparency	Day	36% 7% 11% 23% 18% 5%	108187
	Night	33% 6% 11% 23% 20% 6%	109423
Seeing	Day	16% 10% 22% 27% 20% 5%	15644
	Night	16% 8% 22% 33% 18% 2	25569

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	19% 9% 2 5% 3 3 3 2 3 4 47%	2937
	11th to 20th	Day	13% 9% 3 5% 3 3 3 3 3 4 52%	2940
	21st to end	Day	25% 6% 2 4 2 2 3 2 3 4 46%	3144
February	1st to 10th	Day	24% 9% 2 5% 3 2 2 2 3 4 45%	1710
	11th to 20th	Day	21% 7% 2 5% 3 3 3 3 4 5% 44%	1718
	21st to end	Day	21% 9% 3 6% 3 4 3 2 4 5% 40%	1677
March	1st to 10th	Day	23% 9% 2 5% 3 3 3 2 3 5% 41%	3436
	11th to 20th	Day	15% 6% 2 5% 4 3 4 3 4 6% 47%	3480
	21st to end	Day	19% 8% 2 6% 4 3 3 2 4 5% 41%	3814
April	1st to 10th	Day	18% 6% 2 6% 4 4 4 3 5% 6% 43%	2235
	11th to 20th	Day	20% 7% 2 5% 3 3 3 4 5% 6% 42%	2254
	21st to end	Day	23% 7% 2 6% 4 4 4 3 4 5% 40%	2280
May	1st to 10th	Day	22% 8% 3 6% 5% 4 4 3 5% 5% 34%	3912
	11th to 20th	Day	14% 6% 2 6% 5% 5% 4 4 5% 8% 40%	4082
	21st to end	Day	17% 7% 3 8% 4 5% 5% 4 6% 7% 34%	4477
June	1st to 10th	Day	10% 6% 2 5% 4 5% 5% 5% 7% 9% 42%	2470
	11th to 20th	Day	7% 5% 2 5% 5% 5% 6% 5% 8% 10% 43%	2470
	21st to end	Day	5% 4 1 4 4 4 6% 5% 7% 9% 51%	2470
July	1st to 10th	Day	10% 5% 2 5% 4 4 5% 4 6% 11% 44%	4120
	11th to 20th	Day	5% 4 1 4 4 4 4 4 6% 8% 55%	4120
	21st to end	Day	9% 6% 3 7% 6% 6% 6% 5% 7% 9% 35%	4465
August	1st to 10th	Day	4 3 1 4 3 3 4 4 5% 9% 60%	4104
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 6% 9% 44%	3864
	21st to end	Day	5% 3 1 3 4 4 5% 4 6% 8% 57%	4180
September	1st to 10th	Day	11% 5% 3 5% 3 3 5% 4 5% 7% 50%	2280
	11th to 20th	Day	13% 3 2 5% 3 5% 4 3 6% 8% 47%	2202
	21st to end	Day	9% 4 2 5% 4 3 4 3 5% 6% 54%	2019
October	1st to 10th	Day	10% 4 2 4 3 4 4 3 4 5% 58%	1900
	11th to 20th	Day	15% 4 2 4 2 2 3 2 4 5% 58%	1900
	21st to end	Day	21% 6% 1 4 2 3 3 3 3 4 50%	2090
November	1st to 10th	Day	15% 6% 2 4 3 2 3 2 4 5% 55%	1958
	11th to 20th	Day	14% 5% 1 4 3 3 3 3 4 5% 55%	2000
	21st to end	Day	21% 6% 2 5% 2 2 3 3 3 4 48%	1662
December	1st to 10th	Day	17% 8% 2 5% 2 3 2 2 4 4 51%	2610
	11th to 20th	Day	21% 7% 2 4 4 3 3 2 3 5% 44%	3072
	21st to end	Day	24% 11% 3 7% 3 3 3 2 4 5% 36%	4488
January	1st to 10th	Night	16% 8% 2 6% 4 4 4 3 4 5% 44%	4238
	11th to 20th	Night	15% 6% 1 4 3 2 2 2 4 4 57%	4250
	21st to end	Night	25% 7% 2 4 2 2 2 2 3 4 47%	4546
February	1st to 10th	Night	21% 8% 2 5% 3 3 3 2 4 5% 43%	2470
	11th to 20th	Night	18% 7% 2 5% 3 3 3 3 4 6% 46%	2347
	21st to end	Night	21% 6% 2 5% 3 2 3 2 4 5% 48%	1793
March	1st to 10th	Night	24% 6% 2 6% 3 4 3 3 4 5% 41%	3419
	11th to 20th	Night	18% 6% 2 5% 3 3 3 2 3 5% 49%	3480
	21st to end	Night	17% 7% 2 6% 3 4 3 3 4 6% 45%	3817
April	1st to 10th	Night	16% 5% 2 4 3 3 3 3 5% 6% 48%	1943
	11th to 20th	Night	16% 5% 2 5% 4 4 3 3 4 6% 48%	1875
	21st to end	Night	19% 6% 2 5% 4 4 3 3 5% 7% 42%	1900
May	1st to 10th	Night	22% 7% 2 5% 4 3 3 3 5% 6% 40%	2984
	11th to 20th	Night	15% 7% 3 6% 4 4 4 3 6% 7% 42%	2823
	21st to end	Night	18% 7% 2 5% 4 4 4 3 6% 8% 40%	3090
June	1st to 10th	Night	7% 4 1 5% 3 4 3 4 6% 10% 52%	1710
	11th to 20th	Night	5% 3 1 3 3 3 3 4 7% 11% 57%	1710
	21st to end	Night	5% 4 1 4 3 3 3 4 6% 9% 59%	1710
July	1st to 10th	Night	9% 4 2 5% 4 5% 4 3 6% 9% 48%	2850
	11th to 20th	Night	4 3 1 3 3 3 3 3 6% 9% 61%	2850
	21st to end	Night	7% 6% 3 7% 5% 5% 5% 4 7% 8% 42%	3098
August	1st to 10th	Night	2 2 1 4 3 3 4 3 6% 9% 62%	2836
	11th to 20th	Night	6% 4 2 5% 4 4 4 4 6% 9% 53%	2966
	21st to end	Night	4 3 2 4 3 3 4 4 6% 8% 58%	3476
September	1st to 10th	Night	8% 5% 2 4 3 3 3 3 6% 8% 56%	1900
	11th to 20th	Night	9% 5% 2 5% 4 4 4 3 5% 8% 51%	1973
	21st to end	Night	9% 4 1 4 3 4 3 3 6% 6% 57%	2140
October	1st to 10th	Night	9% 3 1 3 2 3 3 3 6% 7% 60%	2280
	11th to 20th	Night	15% 3 1 4 3 2 2 2 3 4 60%	2280
	21st to end	Night	20% 5% 2 4 3 2 2 2 3 4 53%	2508
November	1st to 10th	Night	14% 6% 2 5% 3 3 3 2 3 5% 55%	2340
	11th to 20th	Night	15% 5% 1 3 3 2 2 3 5% 5% 57%	2400
	21st to end	Night	20% 5% 2 3 2 3 3 2 4 6% 51%	2728
December	1st to 10th	Night	15% 6% 2 4 3 3 3 2 3 5% 52%	4580
	11th to 20th	Night	22% 6% 2 5% 3 2 3 2 3 4 47%	5130
	21st to end	Night	26% 8% 2 7% 4 3 3 2 3 4 37%	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	40% 5% 8% 23% 20% 3	2938
	11th to 20th	Day	37% 5% 11% 23% 20% 3	2940
	21st to end	Day	43% 5% 7% 18% 20% 7%	3144
February	1st to 10th	Day	45% 3 11% 21% 16% 4	1710
	11th to 20th	Day	42% 6% 8% 21% 19% 4	1727
	21st to end	Day	49% 3 9% 15% 16% 8%	1677
March	1st to 10th	Day	43% 8% 8% 15% 16% 11%	3436
	11th to 20th	Day	37% 7% 10% 22% 20% 4	3480
	21st to end	Day	44% 6% 9% 24% 15% 1	3814
April	1st to 10th	Day	41% 6% 9% 19% 21% 4	2235
	11th to 20th	Day	42% 7% 9% 20% 17% 5%	2254
	21st to end	Day	46% 6% 8% 20% 17% 2	2280
May	1st to 10th	Day	47% 9% 10% 18% 15% 1	3947
	11th to 20th	Day	38% 11% 13% 25% 13% 1	4086
	21st to end	Day	44% 11% 12% 18% 13% 1	4489
June	1st to 10th	Day	35% 10% 14% 26% 14% 1	2470
	11th to 20th	Day	32% 10% 16% 23% 17% 2	2470
	21st to end	Day	27% 9% 16% 28% 17% 4	2470
July	1st to 10th	Day	33% 8% 19% 27% 11% 2	4056
	11th to 20th	Day	25% 6% 12% 34% 20% 2	4051
	21st to end	Day	40% 10% 18% 24% 7% 1	4325
August	1st to 10th	Day	21% 7% 17% 30% 20% 5%	4090
	11th to 20th	Day	35% 7% 17% 28% 12% 1	3903
	21st to end	Day	24% 7% 15% 35% 15% 3	4179
September	1st to 10th	Day	32% 8% 12% 22% 18% 8%	2280
	11th to 20th	Day	32% 8% 12% 22% 22% 4	2202
	21st to end	Day	29% 7% 11% 21% 27% 6%	2019
October	1st to 10th	Day	17% 3 6% 13% 39% 23%	3160
	11th to 20th	Day	19% 3 5% 20% 37% 17%	3140
	21st to end	Day	33% 4 8% 29% 21% 5%	3428
November	1st to 10th	Day	33% 5% 9% 25% 21% 8%	1958
	11th to 20th	Day	32% 4 9% 23% 23% 10%	2000
	21st to end	Day	40% 4 8% 20% 23% 5%	1662
December	1st to 10th	Day	37% 4 7% 29% 21% 3	2610
	11th to 20th	Day	43% 4 8% 21% 21% 3	3069
	21st to end	Day	50% 6% 8% 21% 12% 3	4488
January	1st to 10th	Night	40% 7% 9% 20% 22% 3	4238
	11th to 20th	Night	31% 5% 13% 23% 25% 3	4250
	21st to end	Night	42% 4 11% 17% 22% 4	4546
February	1st to 10th	Night	44% 4 9% 22% 17% 4	2470
	11th to 20th	Night	40% 4 9% 22% 19% 6%	2348
	21st to end	Night	40% 4 8% 20% 20% 9%	1793
March	1st to 10th	Night	43% 7% 9% 15% 16% 10%	3419
	11th to 20th	Night	37% 6% 9% 24% 19% 4	3480
	21st to end	Night	38% 7% 12% 25% 16% 2	3817
April	1st to 10th	Night	35% 6% 11% 21% 20% 7%	1943
	11th to 20th	Night	36% 6% 9% 22% 19% 8%	1875
	21st to end	Night	40% 7% 10% 23% 19% 2	1900
May	1st to 10th	Night	42% 9% 12% 20% 14% 3	3014
	11th to 20th	Night	37% 9% 14% 26% 13% 1	2824
	21st to end	Night	39% 11% 14% 21% 13% 2	3099
June	1st to 10th	Night	25% 9% 15% 30% 18% 3	1710
	11th to 20th	Night	20% 7% 16% 33% 22% 2	1710
	21st to end	Night	20% 6% 18% 27% 23% 7%	1710
July	1st to 10th	Night	30% 8% 20% 22% 18% 2	2805
	11th to 20th	Night	18% 7% 13% 38% 23% 2	2796
	21st to end	Night	35% 10% 17% 26% 11% 1	2999
August	1st to 10th	Night	17% 6% 19% 32% 24% 2	2826
	11th to 20th	Night	26% 7% 21% 29% 15% 2	2993
	21st to end	Night	21% 7% 14% 33% 23% 2	3476
September	1st to 10th	Night	25% 8% 10% 30% 18% 9%	1900
	11th to 20th	Night	31% 8% 12% 20% 23% 6%	1973
	21st to end	Night	25% 7% 10% 21% 29% 8%	2140
October	1st to 10th	Night	14% 4 9% 13% 31% 29%	3800
	11th to 20th	Night	18% 2 4 15% 40% 21%	3779
	21st to end	Night	30% 4 5% 25% 27% 9%	4120
November	1st to 10th	Night	32% 4 9% 23% 23% 9%	2340
	11th to 20th	Night	29% 4 8% 24% 26% 10%	2400
	21st to end	Night	36% 4 8% 21% 26% 5%	2728
December	1st to 10th	Night	36% 3 8% 31% 19% 3	4580
	11th to 20th	Night	42% 3 6% 20% 20% 8%	5132
	21st to end	Night	47% 6% 11% 22% 11% 4	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	27% 16% 30% 22% 5%	300
	11th to 20th	Day	25% 23% 33% 14% 4 1	300
	21st to end	Day	21% 24% 32% 17% 6%	300
February	1st to 10th	Day	29% 17% 34% 15% 4 1	270
	11th to 20th	Day	27% 23% 32% 15% 3	270
	21st to end	Day	36% 23% 29% 10% 3	225
March	1st to 10th	Day	24% 20% 33% 17% 5%	270
	11th to 20th	Day	28% 23% 35% 12% 2	270
	21st to end	Day	26% 23% 35% 11% 4	297
April	1st to 10th	Day	22% 18% 33% 18% 9%	415
	11th to 20th	Day	26% 15% 32% 20% 7% 1	452
	21st to end	Day	22% 16% 32% 20% 8% 2	460
May	1st to 10th	Day	19% 19% 28% 25% 9% 1	545
	11th to 20th	Day	18% 9% 24% 30% 16% 3	675
	21st to end	Day	11% 8% 26% 34% 16% 4	734
June	1st to 10th	Day	11% 5% 16% 31% 30% 7%	680
	11th to 20th	Day	8% 2 16% 35% 33% 7%	680
	21st to end	Day	5% 3 20% 37% 28% 8%	680
July	1st to 10th	Day	7% 3 12% 33% 35% 10%	671
	11th to 20th	Day	6% 2 11% 31% 35% 15%	668
	21st to end	Day	6% 2 9% 30% 39% 13%	739
August	1st to 10th	Day	7% 1 12% 35% 36% 9%	676
	11th to 20th	Day	15% 2 10% 30% 35% 9%	566
	21st to end	Day	10% 1 5% 26% 41% 15%	539
September	1st to 10th	Day	10% 2 7% 29% 41% 10%	490
	11th to 20th	Day	9% 3 15% 30% 33% 10%	412
	21st to end	Day	13% 5% 20% 32% 23% 6%	300
October	1st to 10th	Day	7% 4 25% 35% 25% 4	300
	11th to 20th	Day	13% 15% 24% 32% 16% 1	300
	21st to end	Day	28% 15% 25% 23% 8% 1	330
November	1st to 10th	Day	19% 11% 28% 29% 12% 2	300
	11th to 20th	Day	16% 14% 36% 26% 6% 1	300
	21st to end	Day	26% 17% 21% 26% 8% 2	300
December	1st to 10th	Day	24% 16% 31% 20% 7% 2	300
	11th to 20th	Day	26% 15% 31% 21% 7%	300
	21st to end	Day	29% 18% 33% 18% 3	330
January	1st to 10th	Night	23% 12% 29% 32% 5%	1000
	11th to 20th	Night	21% 13% 33% 29% 4	1000
	21st to end	Night	21% 11% 32% 31% 4	1051
February	1st to 10th	Night	24% 13% 30% 29% 4	950
	11th to 20th	Night	22% 14% 36% 25% 3	873
	21st to end	Night	24% 16% 34% 25% 1	537
March	1st to 10th	Night	23% 10% 28% 35% 4	570
	11th to 20th	Night	24% 11% 25% 35% 5%	570
	21st to end	Night	22% 10% 33% 28% 7%	627
April	1st to 10th	Night	18% 12% 34% 29% 7%	570
	11th to 20th	Night	16% 11% 32% 31% 9%	563
	21st to end	Night	20% 10% 30% 30% 10%	570
May	1st to 10th	Night	17% 7% 25% 40% 11%	570
	11th to 20th	Night	15% 7% 23% 33% 22% 1	561
	21st to end	Night	10% 4 21% 39% 23% 3	617
June	1st to 10th	Night	6% 4 11% 36% 41% 2	570
	11th to 20th	Night	4 1 9% 45% 38% 2	570
	21st to end	Night	5% 1 11% 35% 44% 4	570
July	1st to 10th	Night	5% 1 9% 33% 45% 8%	555
	11th to 20th	Night	4 1 8% 32% 45% 10%	552
	21st to end	Night	6% 1 4 33% 46% 10%	624
August	1st to 10th	Night	5% 1 7% 32% 49% 6%	567
	11th to 20th	Night	10% 2 8% 36% 40% 5%	564
	21st to end	Night	7% 2 6% 32% 47% 7%	627
September	1st to 10th	Night	9% 2 6% 35% 44% 4	570
	11th to 20th	Night	11% 2 11% 35% 36% 4	570
	21st to end	Night	11% 3 12% 36% 34% 4	620
October	1st to 10th	Night	10% 3 16% 37% 30% 4	760
	11th to 20th	Night	15% 7% 24% 37% 17%	760
	21st to end	Night	21% 9% 23% 31% 14% 2	836
November	1st to 10th	Night	16% 8% 24% 35% 16% 1	780
	11th to 20th	Night	16% 10% 26% 38% 10%	800
	21st to end	Night	20% 11% 26% 29% 13%	945
December	1st to 10th	Night	22% 8% 30% 33% 7%	1000
	11th to 20th	Night	24% 11% 24% 36% 6%	1000
	21st to end	Night	24% 15% 25% 32% 5%	1100

Page generated at 2025-01-19 02:06:45. Version ac07

Copyright © 2025 Attilla Danko.