Camp Onas
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Onas clear sky chart from 2005-11-06 to 2024-11-05.

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 5% 7% 39%	101370
	Night	17% 7% 2 6% 4 4 4 3 5% 6% 41%	97696
Transparency	Day	43% 4 11% 24% 16% 2	104903
	Night	42% 3 11% 24% 16% 2	102252
Seeing	Day	21% 17% 29% 21% 10% 3	14965
	Night	20% 15% 30% 25% 9% 1	24194

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 7% 4 4 3 3 4 5% 45%	2517
	11th to 20th	Day	14% 10% 4 11% 5% 5% 4 3 5% 6% 34%	2552
	21st to end	Day	21% 10% 3 8% 5% 4 4 3 4 5% 35%	3124
February	1st to 10th	Day	17% 7% 3 6% 5% 4 4 4 6% 7% 38%	1710
	11th to 20th	Day	16% 9% 3 8% 5% 4 4 3 5% 5% 40%	1800
	21st to end	Day	20% 9% 3 6% 4 4 4 3 4 5% 37%	1570
March	1st to 10th	Day	26% 8% 2 6% 4 3 3 2 4 5% 37%	3116
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 5% 5% 7% 44%	3468
	21st to end	Day	21% 7% 2 5% 3 2 3 3 4 5% 43%	4056
April	1st to 10th	Day	17% 8% 3 6% 5% 4 4 3 5% 5% 39%	2280
	11th to 20th	Day	17% 7% 2 5% 5% 4 4 3 5% 8% 41%	2254
	21st to end	Day	16% 6% 2 6% 5% 5% 4 4 6% 6% 39%	2280
May	1st to 10th	Day	27% 8% 3 6% 4 4 4 3 5% 7% 29%	4114
	11th to 20th	Day	25% 9% 3 7% 5% 4 4 3 5% 6% 29%	4398
	21st to end	Day	13% 6% 2 6% 3 4 4 4 6% 9% 44%	4837
June	1st to 10th	Day	14% 6% 2 6% 5% 4 5% 5% 6% 9% 38%	2660
	11th to 20th	Day	13% 7% 2 6% 6% 5% 5% 4 6% 9% 37%	2660
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 4 6% 8% 41%	2660
July	1st to 10th	Day	8% 5% 3 7% 5% 5% 7% 5% 7% 10% 37%	4440
	11th to 20th	Day	9% 6% 2 6% 4 5% 5% 4 7% 11% 40%	4440
	21st to end	Day	13% 8% 3 8% 6% 5% 5% 5% 6% 8% 34%	4787
August	1st to 10th	Day	21% 5% 2 6% 5% 4 6% 5% 6% 8% 32%	4104
	11th to 20th	Day	13% 6% 2 5% 4 4 5% 4 6% 10% 42%	3739
	21st to end	Day	12% 5% 2 5% 3 3 4 3 5% 8% 48%	4180
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 4 5% 6% 44%	2280
	11th to 20th	Day	13% 4 2 4 3 3 4 3 5% 8% 50%	2246
	21st to end	Day	19% 6% 2 8% 4 4 4 3 5% 6% 39%	2090
October	1st to 10th	Day	19% 6% 2 5% 3 4 5% 3 5% 6% 43%	1908
	11th to 20th	Day	14% 6% 2 5% 4 4 4 3 5% 6% 48%	1900
	21st to end	Day	19% 7% 2 5% 3 4 4 3 4 6% 44%	2007
November	1st to 10th	Day	14% 6% 2 5% 3 2 3 3 4 6% 52%	1708
	11th to 20th	Day	17% 5% 2 4 3 3 4 4 5% 6% 46%	1710
	21st to end	Day	15% 6% 2 5% 4 3 4 3 6% 7% 44%	1577
December	1st to 10th	Day	18% 8% 2 7% 4 3 4 3 6% 7% 37%	1520
	11th to 20th	Day	20% 8% 2 6% 4 4 3 3 4 6% 41%	1906
	21st to end	Day	18% 7% 3 8% 6% 5% 5% 4 5% 6% 32%	2772
January	1st to 10th	Night	16% 7% 2 6% 3 4 4 3 5% 6% 45%	4429
	11th to 20th	Night	17% 9% 3 7% 4 4 4 3 4 6% 41%	4408
	21st to end	Night	25% 9% 2 5% 3 3 3 3 4 5% 37%	4532
February	1st to 10th	Night	16% 9% 3 5% 5% 4 3 4 5% 6% 41%	2470
	11th to 20th	Night	17% 9% 2 7% 4 4 4 3 4 5% 41%	2265
	21st to end	Night	19% 8% 2 5% 4 3 4 4 5% 6% 41%	1884
March	1st to 10th	Night	23% 10% 3 5% 3 4 3 2 4 5% 37%	3724
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 4 6% 49%	3488
	21st to end	Night	18% 8% 3 6% 4 3 3 2 4 4 45%	3575
April	1st to 10th	Night	18% 6% 3 6% 4 4 4 4 6% 6% 39%	1900
	11th to 20th	Night	16% 7% 2 7% 5% 4 4 4 5% 7% 40%	1875
	21st to end	Night	19% 6% 1 5% 4 2 3 3 5% 8% 43%	1900
May	1st to 10th	Night	26% 9% 3 5% 4 4 4 4 6% 7% 29%	2856
	11th to 20th	Night	25% 10% 3 7% 4 4 4 3 5% 7% 29%	2495
	21st to end	Night	14% 6% 2 6% 4 4 3 3 7% 9% 41%	2738
June	1st to 10th	Night	16% 7% 2 6% 4 3 4 4 5% 7% 43%	1520
	11th to 20th	Night	12% 5% 2 5% 5% 4 5% 5% 7% 8% 41%	1520
	21st to end	Night	11% 4 2 5% 5% 5% 6% 4 7% 9% 43%	1520
July	1st to 10th	Night	9% 5% 2 7% 6% 6% 5% 4 8% 9% 38%	2520
	11th to 20th	Night	11% 6% 2 6% 5% 4 6% 5% 8% 11% 37%	2520
	21st to end	Night	16% 7% 2 5% 4 5% 5% 5% 7% 8% 37%	2762
August	1st to 10th	Night	22% 6% 2 6% 4 4 5% 4 6% 8% 33%	2825
	11th to 20th	Night	14% 7% 2 6% 5% 4 5% 4 6% 7% 40%	3058
	21st to end	Night	11% 5% 2 5% 4 3 4 4 6% 8% 49%	3476
September	1st to 10th	Night	15% 6% 3 5% 4 4 4 3 4 6% 47%	1900
	11th to 20th	Night	12% 6% 1 5% 3 3 3 3 4 7% 53%	1933
	21st to end	Night	18% 6% 2 6% 4 4 4 3 5% 6% 42%	2090
October	1st to 10th	Night	19% 6% 3 6% 3 4 3 3 4 6% 43%	2270
	11th to 20th	Night	16% 4 2 5% 3 4 3 3 5% 5% 50%	2280
	21st to end	Night	20% 6% 2 4 3 2 3 3 4 6% 46%	2589
November	1st to 10th	Night	13% 5% 2 5% 3 3 3 3 4 6% 53%	2470
	11th to 20th	Night	18% 6% 2 5% 3 3 4 3 3 4 48%	2470
	21st to end	Night	14% 6% 2 6% 4 4 4 3 7% 7% 44%	2602
December	1st to 10th	Night	20% 7% 3 5% 4 4 4 3 5% 6% 39%	2660
	11th to 20th	Night	18% 6% 2 6% 4 4 4 4 6% 6% 40%	3288
	21st to end	Night	19% 8% 3 7% 5% 4 3 3 4 6% 37%	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	43% 2 11% 28% 13% 3	2518
	11th to 20th	Day	51% 3 10% 21% 12% 2	2552
	21st to end	Day	53% 2 11% 22% 10% 1	3124
February	1st to 10th	Day	46% 4 14% 24% 12% 2	1710
	11th to 20th	Day	47% 3 8% 24% 15% 2	1809
	21st to end	Day	50% 3 8% 23% 12% 4	1570
March	1st to 10th	Day	52% 3 7% 27% 9% 2	3119
	11th to 20th	Day	38% 4 10% 31% 15% 3	3468
	21st to end	Day	45% 2 9% 18% 22% 4	4056
April	1st to 10th	Day	46% 4 8% 22% 15% 5%	2280
	11th to 20th	Day	42% 4 12% 22% 17% 4	2254
	21st to end	Day	44% 4 10% 21% 17% 4	2280
May	1st to 10th	Day	55% 4 11% 18% 11% 2	4128
	11th to 20th	Day	57% 3 10% 19% 9% 1	4402
	21st to end	Day	37% 5% 11% 27% 18% 2	4837
June	1st to 10th	Day	41% 7% 13% 24% 15% 1	2660
	11th to 20th	Day	43% 5% 14% 24% 11% 2	2660
	21st to end	Day	39% 5% 15% 26% 15% 1	2660
July	1st to 10th	Day	41% 6% 14% 22% 14% 2	4370
	11th to 20th	Day	38% 4 16% 27% 13% 1	4365
	21st to end	Day	49% 4 10% 20% 17% 1	4634
August	1st to 10th	Day	48% 5% 13% 24% 10%	4091
	11th to 20th	Day	39% 3 13% 30% 14% 1	3775
	21st to end	Day	35% 3 10% 30% 20% 2	4180
September	1st to 10th	Day	40% 5% 11% 21% 21% 3	2280
	11th to 20th	Day	33% 4 10% 26% 25% 3	2246
	21st to end	Day	47% 3 8% 20% 20% 2	2090
October	1st to 10th	Day	39% 3 8% 20% 25% 5%	3168
	11th to 20th	Day	28% 2 10% 27% 27% 5%	3140
	21st to end	Day	27% 2 13% 25% 28% 4	3284
November	1st to 10th	Day	35% 3 12% 25% 21% 3	1708
	11th to 20th	Day	39% 4 9% 26% 20% 2	1710
	21st to end	Day	39% 3 13% 30% 12% 2	1577
December	1st to 10th	Day	48% 3 16% 21% 12% 1	1520
	11th to 20th	Day	46% 3 15% 24% 10% 2	1906
	21st to end	Day	52% 3 11% 24% 9%	2772
January	1st to 10th	Night	42% 2 10% 31% 12% 3	4429
	11th to 20th	Night	47% 2 12% 26% 11% 2	4408
	21st to end	Night	50% 2 8% 26% 12% 2	4532
February	1st to 10th	Night	45% 3 13% 26% 11% 2	2470
	11th to 20th	Night	46% 4 8% 21% 18% 4	2267
	21st to end	Night	44% 4 7% 24% 17% 4	1884
March	1st to 10th	Night	51% 2 8% 25% 12% 2	3734
	11th to 20th	Night	37% 3 13% 28% 16% 2	3489
	21st to end	Night	45% 2 6% 18% 23% 6%	3575
April	1st to 10th	Night	44% 4 10% 22% 16% 4	1900
	11th to 20th	Night	44% 4 9% 22% 19% 2	1875
	21st to end	Night	40% 5% 9% 22% 20% 5%	1900
May	1st to 10th	Night	55% 3 10% 21% 10% 1	2862
	11th to 20th	Night	56% 4 14% 15% 10% 1	2496
	21st to end	Night	39% 5% 15% 23% 14% 3	2739
June	1st to 10th	Night	40% 7% 11% 23% 19% 2	1520
	11th to 20th	Night	38% 7% 14% 26% 13% 1	1520
	21st to end	Night	37% 6% 14% 28% 15% 1	1520
July	1st to 10th	Night	42% 6% 17% 18% 15% 2	2480
	11th to 20th	Night	40% 5% 16% 26% 12% 1	2472
	21st to end	Night	45% 5% 13% 18% 17% 1	2674
August	1st to 10th	Night	49% 4 19% 18% 9% 1	2814
	11th to 20th	Night	43% 4 12% 25% 15% 1	3088
	21st to end	Night	34% 3 10% 31% 21% 1	3476
September	1st to 10th	Night	40% 5% 10% 21% 22% 2	1900
	11th to 20th	Night	33% 3 10% 23% 26% 4	1933
	21st to end	Night	43% 3 8% 22% 22% 1	2090
October	1st to 10th	Night	43% 3 9% 23% 21% 2	3790
	11th to 20th	Night	27% 2 9% 30% 28% 4	3779
	21st to end	Night	29% 2 11% 33% 22% 3	4262
November	1st to 10th	Night	33% 4 12% 25% 21% 4	2470
	11th to 20th	Night	40% 3 9% 24% 20% 4	2470
	21st to end	Night	39% 3 12% 28% 15% 2	2602
December	1st to 10th	Night	47% 3 12% 23% 14% 1	2660
	11th to 20th	Night	43% 4 13% 21% 16% 3	3288
	21st to end	Night	49% 3 12% 26% 10% 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	24% 31% 29% 14% 1 1	180
	11th to 20th	Day	30% 33% 26% 9% 2	189
	21st to end	Day	23% 31% 30% 11% 4	297
February	1st to 10th	Day	28% 30% 32% 7% 4	270
	11th to 20th	Day	29% 28% 32% 9% 1	408
	21st to end	Day	34% 23% 27% 13% 3	382
March	1st to 10th	Day	28% 24% 30% 15% 4	460
	11th to 20th	Day	25% 29% 30% 13% 2 1	460
	21st to end	Day	28% 26% 30% 10% 5% 1	506
April	1st to 10th	Day	25% 27% 28% 14% 5% 1	460
	11th to 20th	Day	24% 25% 30% 12% 6% 2	452
	21st to end	Day	27% 18% 34% 15% 4 2	460
May	1st to 10th	Day	31% 20% 28% 14% 5% 2	463
	11th to 20th	Day	23% 16% 32% 21% 7% 1	487
	21st to end	Day	19% 10% 29% 26% 15% 2	529
June	1st to 10th	Day	16% 14% 31% 26% 11% 2	490
	11th to 20th	Day	16% 15% 26% 27% 12% 3	490
	21st to end	Day	16% 12% 33% 25% 11% 2	490
July	1st to 10th	Day	11% 8% 23% 32% 20% 7%	485
	11th to 20th	Day	10% 5% 27% 32% 22% 5%	484
	21st to end	Day	14% 7% 32% 31% 13% 4	532
August	1st to 10th	Day	12% 7% 27% 30% 18% 6%	486
	11th to 20th	Day	15% 7% 21% 33% 19% 6%	479
	21st to end	Day	14% 5% 28% 30% 15% 8%	539
September	1st to 10th	Day	19% 10% 23% 26% 14% 7%	490
	11th to 20th	Day	15% 5% 28% 26% 17% 9%	490
	21st to end	Day	24% 13% 25% 23% 11% 4	490
October	1st to 10th	Day	25% 10% 27% 20% 12% 6%	490
	11th to 20th	Day	18% 17% 31% 24% 8% 2	490
	21st to end	Day	22% 16% 34% 15% 11% 1	494
November	1st to 10th	Day	20% 13% 31% 23% 11% 2	378
	11th to 20th	Day	22% 23% 31% 19% 5% 1	370
	21st to end	Day	20% 25% 36% 14% 4	237
December	1st to 10th	Day	26% 30% 29% 9% 6%	180
	11th to 20th	Day	31% 28% 24% 12% 4	180
	21st to end	Day	28% 23% 30% 13% 5% 1	198
January	1st to 10th	Night	19% 27% 35% 16% 2	760
	11th to 20th	Night	26% 21% 30% 20% 3	760
	21st to end	Night	19% 25% 35% 19% 1	836
February	1st to 10th	Night	22% 21% 35% 21% 1	760
	11th to 20th	Night	24% 29% 34% 12% 1	743
	21st to end	Night	26% 24% 32% 16% 2	628
March	1st to 10th	Night	24% 24% 31% 19% 3	760
	11th to 20th	Night	23% 25% 32% 16% 4 1	760
	21st to end	Night	23% 20% 36% 16% 5%	836
April	1st to 10th	Night	21% 24% 34% 17% 4	760
	11th to 20th	Night	22% 17% 36% 19% 6%	751
	21st to end	Night	23% 15% 33% 23% 5%	760
May	1st to 10th	Night	26% 13% 31% 23% 7%	592
	11th to 20th	Night	21% 11% 37% 22% 10%	374
	21st to end	Night	17% 6% 25% 39% 12% 2	411
June	1st to 10th	Night	17% 8% 27% 36% 13%	380
	11th to 20th	Night	14% 6% 30% 39% 11% 1	380
	21st to end	Night	11% 3 27% 47% 11% 1	380
July	1st to 10th	Night	12% 4 25% 39% 18% 2	370
	11th to 20th	Night	9% 3 27% 40% 20% 1	368
	21st to end	Night	11% 5% 24% 39% 20% 2	427
August	1st to 10th	Night	13% 2 17% 42% 23% 2	567
	11th to 20th	Night	14% 3 17% 39% 25% 2	723
	21st to end	Night	15% 4 17% 39% 23% 2	836
September	1st to 10th	Night	18% 3 27% 34% 17% 2	760
	11th to 20th	Night	15% 5% 22% 33% 21% 4	760
	21st to end	Night	21% 7% 23% 31% 17% 1	760
October	1st to 10th	Night	21% 9% 26% 24% 16% 3	760
	11th to 20th	Night	17% 12% 29% 29% 12%	760
	21st to end	Night	23% 15% 31% 23% 8%	836
November	1st to 10th	Night	15% 15% 33% 25% 11% 1	760
	11th to 20th	Night	21% 19% 28% 24% 7%	760
	21st to end	Night	17% 20% 34% 23% 6% 1	760
December	1st to 10th	Night	26% 20% 30% 18% 5% 1	760
	11th to 20th	Night	20% 20% 35% 20% 4	760
	21st to end	Night	22% 20% 33% 22% 3	836

Page generated at 2024-11-03 02:11:30. Version ac07

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