Pine Cone Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pine Cone Observatory clear sky chart from 2005-11-06 to 2024-11-12.

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	16% 7% 2 6% 4 4 4 4 6% 7% 40%	101349
	Night	16% 7% 2 6% 4 4 4 3 5% 7% 42%	97855
Transparency	Day	41% 7% 12% 22% 16% 3	104907
	Night	40% 6% 12% 23% 17% 3	102386
Seeing	Day	19% 13% 30% 23% 12% 4	15085
	Night	18% 10% 31% 30% 10% 1	24297

By Month

Percentage Cloud Cover NE (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	15% 9% 3 5% 3 4 3 3 4 4 47%	2517
	11th to 20th	Day	15% 8% 2 9% 5% 4 4 3 4 5% 39%	2521
	21st to end	Day	23% 11% 3 6% 4 4 3 2 4 4 35%	3124
February	1st to 10th	Day	15% 8% 3 7% 4 4 3 3 5% 7% 40%	1713
	11th to 20th	Day	17% 7% 2 5% 5% 4 4 3 5% 6% 42%	1848
	21st to end	Day	17% 9% 3 7% 5% 3 4 3 4 6% 39%	1570
March	1st to 10th	Day	27% 7% 2 5% 3 3 3 2 3 5% 39%	3116
	11th to 20th	Day	9% 5% 2 6% 5% 5% 4 4 6% 7% 48%	3403
	21st to end	Day	21% 7% 2 5% 3 3 4 3 4 5% 44%	4096
April	1st to 10th	Day	17% 7% 3 5% 4 4 5% 4 5% 5% 41%	2280
	11th to 20th	Day	15% 6% 3 5% 5% 3 4 4 6% 7% 43%	2254
	21st to end	Day	17% 5% 2 6% 4 4 4 5% 5% 7% 40%	2280
May	1st to 10th	Day	26% 9% 3 7% 4 4 4 3 5% 7% 29%	4060
	11th to 20th	Day	27% 7% 3 7% 4 4 4 3 4 6% 31%	4361
	21st to end	Day	13% 5% 2 5% 4 4 4 4 6% 9% 43%	4837
June	1st to 10th	Day	12% 6% 2 6% 6% 5% 4 5% 7% 9% 39%	2660
	11th to 20th	Day	13% 7% 2 5% 6% 4 6% 4 6% 9% 39%	2660
	21st to end	Day	11% 5% 2 7% 4 5% 6% 5% 6% 9% 41%	2660
July	1st to 10th	Day	8% 5% 2 7% 6% 6% 7% 5% 8% 10% 35%	4440
	11th to 20th	Day	11% 6% 2 6% 5% 5% 6% 6% 8% 10% 35%	4440
	21st to end	Day	11% 9% 3 8% 6% 6% 6% 5% 7% 8% 31%	4814
August	1st to 10th	Day	18% 7% 3 8% 5% 5% 5% 4 7% 8% 30%	4032
	11th to 20th	Day	12% 7% 2 5% 5% 5% 6% 4 7% 8% 37%	3730
	21st to end	Day	10% 5% 2 5% 4 4 6% 5% 8% 10% 41%	4180
September	1st to 10th	Day	13% 6% 2 6% 4 5% 4 4 5% 7% 44%	2280
	11th to 20th	Day	12% 5% 2 6% 3 4 4 3 5% 8% 48%	2218
	21st to end	Day	19% 7% 3 7% 3 4 4 3 5% 6% 40%	2090
October	1st to 10th	Day	19% 7% 2 5% 3 3 3 3 4 6% 44%	1957
	11th to 20th	Day	16% 6% 2 4 3 3 4 3 4 6% 50%	1900
	21st to end	Day	17% 6% 2 5% 3 3 4 3 4 6% 47%	1986
November	1st to 10th	Day	13% 5% 2 4 4 3 3 3 4 6% 53%	1761
	11th to 20th	Day	16% 6% 2 6% 4 3 3 3 4 6% 47%	1719
	21st to end	Day	14% 5% 2 6% 4 4 4 4 5% 6% 46%	1644
December	1st to 10th	Day	18% 8% 2 6% 4 4 3 3 5% 7% 40%	1520
	11th to 20th	Day	19% 8% 3 5% 4 2 3 3 4 5% 45%	1906
	21st to end	Day	16% 7% 2 5% 4 5% 5% 5% 6% 7% 38%	2772
January	1st to 10th	Night	17% 6% 2 5% 3 3 3 3 5% 6% 46%	4429
	11th to 20th	Night	18% 9% 2 6% 3 3 3 3 4 5% 43%	4436
	21st to end	Night	23% 9% 3 6% 4 4 4 3 4 5% 36%	4532
February	1st to 10th	Night	16% 9% 3 5% 4 4 4 3 4 6% 42%	2466
	11th to 20th	Night	18% 9% 2 6% 3 4 3 3 6% 5% 41%	2218
	21st to end	Night	18% 7% 2 7% 3 2 3 3 5% 5% 43%	1884
March	1st to 10th	Night	22% 12% 2 6% 3 3 3 2 3 5% 38%	3724
	11th to 20th	Night	12% 7% 2 6% 4 4 4 3 4 6% 48%	3553
	21st to end	Night	18% 9% 2 7% 3 3 3 3 3 4 43%	3535
April	1st to 10th	Night	16% 8% 3 7% 4 3 4 3 4 6% 41%	1900
	11th to 20th	Night	14% 8% 3 7% 4 4 4 3 4 7% 43%	1875
	21st to end	Night	18% 6% 2 5% 3 3 4 3 6% 8% 43%	1900
May	1st to 10th	Night	21% 11% 4 7% 4 4 3 3 6% 7% 30%	2879
	11th to 20th	Night	25% 9% 3 7% 4 3 3 3 5% 7% 31%	2560
	21st to end	Night	13% 8% 2 6% 5% 4 4 4 4 9% 42%	2738
June	1st to 10th	Night	14% 6% 2 6% 3 3 4 5% 6% 8% 42%	1520
	11th to 20th	Night	10% 7% 2 7% 6% 5% 5% 4 5% 7% 43%	1520
	21st to end	Night	9% 5% 2 5% 5% 5% 5% 6% 8% 11% 41%	1520
July	1st to 10th	Night	7% 6% 3 8% 6% 6% 6% 5% 9% 10% 34%	2520
	11th to 20th	Night	10% 7% 3 7% 4 5% 5% 4 7% 11% 39%	2520
	21st to end	Night	15% 8% 3 7% 5% 4 5% 4 7% 8% 34%	2739
August	1st to 10th	Night	21% 7% 3 7% 4 4 5% 4 6% 8% 31%	2864
	11th to 20th	Night	12% 7% 2 7% 4 4 5% 3 6% 7% 44%	3097
	21st to end	Night	9% 4 2 6% 4 4 4 4 6% 7% 50%	3476
September	1st to 10th	Night	14% 6% 2 6% 4 5% 4 3 4 6% 45%	1900
	11th to 20th	Night	10% 6% 2 4 3 3 4 3 5% 7% 53%	1962
	21st to end	Night	19% 8% 2 5% 4 3 4 3 6% 7% 40%	2090
October	1st to 10th	Night	18% 6% 3 6% 3 3 4 3 4 6% 45%	2219
	11th to 20th	Night	15% 5% 1 5% 3 3 4 3 4 6% 52%	2280
	21st to end	Night	17% 7% 2 5% 3 3 3 3 4 5% 48%	2612
November	1st to 10th	Night	11% 6% 2 6% 3 4 3 2 5% 6% 52%	2537
	11th to 20th	Night	17% 6% 3 6% 3 3 4 3 4 5% 47%	2484
	21st to end	Night	13% 6% 2 5% 5% 4 4 4 5% 7% 46%	2534
December	1st to 10th	Night	20% 7% 2 6% 3 3 4 4 5% 6% 40%	2660
	11th to 20th	Night	17% 6% 2 6% 4 4 4 3 5% 7% 42%	3288
	21st to end	Night	17% 9% 3 6% 4 5% 4 3 5% 6% 39%	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	39% 5% 12% 25% 16% 4	2518
	11th to 20th	Day	45% 5% 11% 22% 14% 3	2521
	21st to end	Day	52% 6% 9% 21% 10% 2	3124
February	1st to 10th	Day	44% 5% 13% 24% 13% 1	1713
	11th to 20th	Day	43% 6% 10% 23% 16% 3	1857
	21st to end	Day	47% 6% 9% 21% 13% 5%	1570
March	1st to 10th	Day	48% 5% 10% 26% 9% 2	3119
	11th to 20th	Day	31% 7% 13% 30% 17% 3	3403
	21st to end	Day	43% 6% 8% 18% 21% 5%	4096
April	1st to 10th	Day	42% 7% 10% 20% 15% 5%	2280
	11th to 20th	Day	38% 7% 14% 22% 17% 3	2254
	21st to end	Day	41% 7% 11% 19% 18% 4	2280
May	1st to 10th	Day	53% 9% 12% 16% 9% 1	4074
	11th to 20th	Day	52% 7% 14% 18% 8% 1	4365
	21st to end	Day	34% 11% 13% 24% 17% 2	4837
June	1st to 10th	Day	40% 10% 13% 21% 15% 2	2660
	11th to 20th	Day	39% 9% 13% 25% 12% 2	2660
	21st to end	Day	38% 10% 12% 22% 16% 1	2660
July	1st to 10th	Day	40% 11% 16% 19% 12% 2	4370
	11th to 20th	Day	41% 9% 17% 19% 13% 1	4365
	21st to end	Day	47% 9% 11% 18% 14% 1	4661
August	1st to 10th	Day	50% 8% 15% 19% 8% 1	4018
	11th to 20th	Day	40% 9% 13% 24% 13% 1	3766
	21st to end	Day	34% 8% 13% 26% 17% 2	4180
September	1st to 10th	Day	38% 7% 13% 18% 21% 3	2280
	11th to 20th	Day	34% 5% 11% 22% 24% 3	2218
	21st to end	Day	46% 6% 8% 18% 19% 3	2090
October	1st to 10th	Day	36% 4 11% 18% 27% 5%	3256
	11th to 20th	Day	24% 4 9% 23% 32% 8%	3140
	21st to end	Day	26% 4 12% 26% 27% 6%	3250
November	1st to 10th	Day	33% 4 13% 26% 20% 3	1761
	11th to 20th	Day	38% 5% 9% 22% 23% 3	1719
	21st to end	Day	37% 6% 12% 30% 13% 2	1644
December	1st to 10th	Day	44% 5% 15% 22% 14% 1	1520
	11th to 20th	Day	41% 5% 12% 27% 13% 2	1906
	21st to end	Day	42% 8% 14% 23% 13% 1	2772
January	1st to 10th	Night	38% 5% 11% 29% 14% 4	4429
	11th to 20th	Night	43% 5% 11% 24% 14% 3	4436
	21st to end	Night	49% 5% 8% 23% 13% 2	4532
February	1st to 10th	Night	43% 6% 13% 23% 13% 2	2466
	11th to 20th	Night	44% 5% 9% 19% 18% 5%	2220
	21st to end	Night	42% 5% 9% 22% 18% 5%	1884
March	1st to 10th	Night	49% 4 9% 22% 12% 3	3734
	11th to 20th	Night	35% 7% 13% 26% 16% 3	3554
	21st to end	Night	45% 5% 7% 16% 22% 5%	3535
April	1st to 10th	Night	43% 5% 10% 19% 18% 5%	1900
	11th to 20th	Night	42% 5% 10% 21% 19% 3	1875
	21st to end	Night	39% 7% 10% 19% 20% 5%	1900
May	1st to 10th	Night	52% 8% 10% 19% 9% 1	2885
	11th to 20th	Night	53% 7% 14% 15% 10% 2	2561
	21st to end	Night	38% 10% 15% 20% 16% 2	2739
June	1st to 10th	Night	39% 9% 11% 21% 18% 2	1520
	11th to 20th	Night	39% 10% 13% 24% 13% 2	1520
	21st to end	Night	34% 9% 17% 22% 16% 2	1520
July	1st to 10th	Night	42% 11% 18% 17% 11% 2	2480
	11th to 20th	Night	39% 9% 18% 24% 10% 1	2472
	21st to end	Night	45% 7% 16% 18% 14% 1	2651
August	1st to 10th	Night	50% 8% 19% 15% 9% 1	2854
	11th to 20th	Night	39% 6% 13% 30% 12% 1	3127
	21st to end	Night	32% 6% 12% 28% 21% 2	3476
September	1st to 10th	Night	39% 8% 12% 18% 20% 3	1900
	11th to 20th	Night	32% 6% 13% 22% 24% 4	1962
	21st to end	Night	42% 7% 8% 21% 19% 2	2090
October	1st to 10th	Night	37% 5% 11% 22% 22% 2	3700
	11th to 20th	Night	24% 3 10% 27% 30% 6%	3779
	21st to end	Night	26% 4 10% 31% 24% 4	4298
November	1st to 10th	Night	32% 5% 12% 24% 21% 5%	2537
	11th to 20th	Night	40% 5% 8% 22% 20% 5%	2484
	21st to end	Night	36% 5% 13% 26% 18% 2	2534
December	1st to 10th	Night	45% 5% 12% 23% 14% 2	2660
	11th to 20th	Night	41% 5% 13% 19% 18% 4	3288
	21st to end	Night	43% 8% 13% 24% 11% 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	21% 22% 36% 16% 4 1	180
	11th to 20th	Day	27% 29% 29% 14% 2	181
	21st to end	Day	25% 23% 31% 15% 5% 1	297
February	1st to 10th	Day	23% 22% 39% 11% 4	273
	11th to 20th	Day	28% 21% 36% 14% 2	456
	21st to end	Day	27% 22% 29% 18% 3	382
March	1st to 10th	Day	22% 22% 32% 20% 4 1	460
	11th to 20th	Day	17% 26% 37% 14% 5% 2	460
	21st to end	Day	24% 20% 32% 19% 6%	506
April	1st to 10th	Day	22% 21% 35% 15% 5% 1	460
	11th to 20th	Day	19% 17% 34% 19% 8% 2	452
	21st to end	Day	25% 16% 34% 17% 6% 2	460
May	1st to 10th	Day	27% 17% 29% 17% 9% 2	463
	11th to 20th	Day	22% 11% 35% 21% 8% 3	487
	21st to end	Day	18% 8% 22% 28% 19% 5%	529
June	1st to 10th	Day	14% 10% 31% 27% 16% 3	490
	11th to 20th	Day	14% 9% 31% 28% 15% 3	490
	21st to end	Day	13% 7% 29% 31% 17% 4	490
July	1st to 10th	Day	14% 3 23% 30% 23% 8%	485
	11th to 20th	Day	7% 2 25% 34% 25% 7%	484
	21st to end	Day	11% 5% 26% 32% 20% 5%	532
August	1st to 10th	Day	11% 5% 25% 33% 19% 8%	486
	11th to 20th	Day	13% 3 22% 31% 23% 8%	479
	21st to end	Day	12% 6% 23% 29% 20% 10%	539
September	1st to 10th	Day	15% 8% 25% 24% 18% 10%	490
	11th to 20th	Day	13% 4 25% 31% 17% 10%	490
	21st to end	Day	25% 8% 26% 25% 13% 4	490
October	1st to 10th	Day	23% 7% 26% 23% 14% 7%	490
	11th to 20th	Day	16% 13% 29% 25% 13% 4	490
	21st to end	Day	18% 12% 33% 23% 12% 2	484
November	1st to 10th	Day	15% 10% 35% 25% 12% 3	395
	11th to 20th	Day	20% 18% 31% 23% 8%	373
	21st to end	Day	17% 15% 33% 25% 9% 1	304
December	1st to 10th	Day	25% 20% 36% 9% 9% 1	180
	11th to 20th	Day	29% 16% 35% 15% 4 1	180
	21st to end	Day	26% 15% 33% 19% 6% 2	198
January	1st to 10th	Night	19% 16% 38% 23% 4	760
	11th to 20th	Night	23% 16% 34% 24% 3	760
	21st to end	Night	19% 15% 40% 24% 2	836
February	1st to 10th	Night	20% 14% 38% 25% 2	760
	11th to 20th	Night	24% 19% 39% 17% 1	743
	21st to end	Night	23% 20% 34% 20% 3	628
March	1st to 10th	Night	21% 15% 38% 22% 4	760
	11th to 20th	Night	20% 17% 36% 21% 5% 1	760
	21st to end	Night	21% 11% 42% 21% 5%	836
April	1st to 10th	Night	20% 18% 38% 19% 6%	760
	11th to 20th	Night	18% 12% 38% 28% 5%	751
	21st to end	Night	20% 9% 36% 28% 6%	760
May	1st to 10th	Night	20% 11% 35% 27% 7%	602
	11th to 20th	Night	22% 9% 35% 30% 5%	413
	21st to end	Night	18% 4 20% 43% 14% 2	411
June	1st to 10th	Night	17% 4 27% 40% 12% 1	380
	11th to 20th	Night	13% 3 25% 44% 15%	380
	21st to end	Night	8% 5% 27% 46% 14%	380
July	1st to 10th	Night	11% 4 19% 45% 20% 1	370
	11th to 20th	Night	8% 4 19% 46% 21% 2	368
	21st to end	Night	9% 3 23% 47% 18% 1	416
August	1st to 10th	Night	11% 2 15% 49% 21% 2	580
	11th to 20th	Night	12% 3 18% 39% 26% 1	750
	21st to end	Night	13% 3 16% 40% 25% 3	836
September	1st to 10th	Night	17% 2 21% 39% 18% 3	760
	11th to 20th	Night	14% 4 18% 37% 23% 5%	760
	21st to end	Night	23% 4 22% 33% 17% 1	760
October	1st to 10th	Night	21% 5% 26% 28% 16% 4	760
	11th to 20th	Night	17% 8% 27% 35% 13% 1	760
	21st to end	Night	19% 8% 34% 28% 10% 1	836
November	1st to 10th	Night	15% 7% 35% 31% 12% 1	780
	11th to 20th	Night	19% 13% 31% 28% 8% 1	765
	21st to end	Night	15% 13% 36% 28% 9% 1	760
December	1st to 10th	Night	24% 13% 35% 21% 7% 1	760
	11th to 20th	Night	19% 13% 37% 25% 6%	760
	21st to end	Night	20% 12% 36% 29% 3	836

Page generated at 2024-11-08 22:45:39. Version ac07

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