Forest Road 006 Site 1
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Forest Road 006 Site 1 clear sky chart from 2005-11-06 to 2026-09-14.

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	2 5% 2 6% 5% 4 5% 4 6% 7% 54%	158001
	Night	3 5% 2 6% 4 5% 5% 4 6% 7% 53%	150735
Transparency	Day	25% 7% 10% 19% 23% 17%	152739
	Night	26% 7% 11% 20% 22% 14%	147017
Seeing	Day	8% 13% 28% 28% 17% 6%	17300
	Night	7% 7% 19% 37% 25% 5%	27401

By Month

Percentage Cloud Cover SW (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	2 8% 5% 13% 8% 6% 5% 5% 6% 8% 34%	5318
	11th to 20th	Day	1 5% 2 10% 6% 5% 5% 3 5% 6% 51%	5340
	21st to end	Day	2 7% 4 9% 4 4 5% 3 5% 7% 50%	5844
February	1st to 10th	Day	3 10% 4 11% 6% 5% 6% 4 5% 8% 38%	1890
	11th to 20th	Day	3 11% 3 11% 7% 6% 5% 4 7% 7% 37%	1975
	21st to end	Day	2 9% 3 7% 6% 6% 5% 5% 6% 7% 43%	1730
March	1st to 10th	Day	2 9% 5% 10% 6% 5% 5% 4 5% 7% 42%	4882
	11th to 20th	Day	2 6% 3 8% 7% 6% 7% 5% 6% 8% 41%	5110
	21st to end	Day	3 8% 4 11% 8% 7% 7% 6% 6% 8% 33%	5607
April	1st to 10th	Day	4 8% 3 7% 7% 5% 5% 4 5% 6% 45%	2310
	11th to 20th	Day	4 8% 3 7% 7% 6% 4 3 6% 7% 45%	2665
	21st to end	Day	5% 8% 2 6% 4 4 5% 5% 6% 7% 48%	2730
May	1st to 10th	Day	4 6% 2 5% 5% 4 5% 4 6% 7% 52%	7626
	11th to 20th	Day	4 5% 2 6% 4 5% 5% 4 6% 7% 52%	7596
	21st to end	Day	3 4 2 5% 5% 5% 5% 4 6% 7% 53%	8370
June	1st to 10th	Day	2 3 1 5% 4 4 4 4 7% 8% 57%	2730
	11th to 20th	Day	4 3 1 3 3 3 3 3 5% 6% 65%	2730
	21st to end	Day	2 2 1 3 3 3 4 3 5% 6% 69%	2730
July	1st to 10th	Day	1 2 1 3 2 3 3 3 4 5% 72%	7649
	11th to 20th	Day	2 3 1 5% 5% 5% 6% 5% 8% 9% 51%	7650
	21st to end	Day	2 2 1 4 3 4 4 4 6% 7% 64%	8304
August	1st to 10th	Day	1 2 1 3 3 3 4 3 5% 7% 69%	7549
	11th to 20th	Day	1 2 1 4 3 4 4 4 5% 7% 65%	7565
	21st to end	Day	2 2 1 5% 4 5% 6% 5% 7% 8% 55%	8344
September	1st to 10th	Day	2 3 1 3 2 2 4 4 5% 7% 67%	2310
	11th to 20th	Day	3 3 1 4 3 3 4 3 5% 7% 65%	2234
	21st to end	Day	3 3 1 4 2 2 3 2 4 6% 70%	2200
October	1st to 10th	Day	3 3 1 3 3 3 4 3 4 4 69%	3485
	11th to 20th	Day	4 6% 2 4 3 3 3 3 5% 7% 61%	3250
	21st to end	Day	4 4 1 6% 4 3 4 3 4 6% 62%	3496
November	1st to 10th	Day	4 5% 2 5% 5% 5% 5% 4 6% 7% 52%	1854
	11th to 20th	Day	5% 6% 2 7% 5% 4 5% 3 6% 8% 49%	1890
	21st to end	Day	3 9% 3 7% 4 5% 5% 4 5% 7% 48%	1890
December	1st to 10th	Day	2 5% 2 5% 3 3 3 2 5% 7% 62%	3040
	11th to 20th	Day	2 6% 2 8% 6% 5% 7% 5% 8% 11% 41%	3499
	21st to end	Day	2 10% 4 12% 8% 6% 6% 5% 6% 7% 34%	4609
January	1st to 10th	Night	1 8% 4 12% 7% 6% 6% 4 6% 7% 38%	7605
	11th to 20th	Night	1 5% 2 8% 6% 5% 4 3 5% 6% 53%	7650
	21st to end	Night	2 6% 3 7% 5% 5% 4 4 5% 7% 53%	8370
February	1st to 10th	Night	3 7% 2 8% 6% 6% 6% 5% 7% 8% 42%	2730
	11th to 20th	Night	3 10% 3 9% 6% 5% 5% 4 5% 7% 43%	2530
	21st to end	Night	2 7% 3 8% 6% 6% 5% 4 6% 7% 47%	2076
March	1st to 10th	Night	3 9% 5% 9% 5% 6% 5% 4 5% 5% 44%	5231
	11th to 20th	Night	3 6% 2 8% 5% 6% 7% 5% 8% 8% 43%	5110
	21st to end	Night	3 7% 2 6% 5% 6% 6% 5% 8% 7% 45%	5610
April	1st to 10th	Night	5% 7% 3 5% 4 4 5% 4 5% 7% 51%	2310
	11th to 20th	Night	4 7% 3 5% 5% 4 4 4 5% 9% 51%	1897
	21st to end	Night	5% 7% 2 5% 4 5% 5% 4 6% 6% 50%	1890
May	1st to 10th	Night	4 5% 2 6% 5% 5% 5% 4 6% 7% 54%	5321
	11th to 20th	Night	3 4 1 5% 3 4 4 4 6% 7% 60%	5296
	21st to end	Night	4 5% 2 6% 4 4 4 4 6% 7% 55%	5837
June	1st to 10th	Night	4 4 1 5% 3 4 4 4 5% 8% 58%	1890
	11th to 20th	Night	3 3 2 4 3 3 4 2 4 6% 66%	1890
	21st to end	Night	2 3 1 5% 3 3 3 5% 5% 7% 63%	1890
July	1st to 10th	Night	1 2 2 5% 4 4 4 3 4 5% 67%	5340
	11th to 20th	Night	3 4 2 8% 5% 6% 7% 6% 8% 8% 43%	5340
	21st to end	Night	2 3 2 6% 4 4 4 3 6% 7% 59%	5805
August	1st to 10th	Night	2 2 1 4 3 4 4 4 5% 6% 66%	5273
	11th to 20th	Night	2 3 2 6% 4 4 5% 3 5% 7% 59%	5291
	21st to end	Night	1 3 2 7% 5% 6% 6% 5% 7% 7% 51%	5857
September	1st to 10th	Night	3 3 1 3 3 3 3 3 5% 6% 68%	2309
	11th to 20th	Night	2 3 1 4 3 4 3 3 4 7% 66%	2233
	21st to end	Night	5% 3 1 3 2 2 3 3 3 5% 71%	2200
October	1st to 10th	Night	3 2 1 3 2 2 3 3 4 5% 71%	3710
	11th to 20th	Night	5% 4 2 4 4 4 4 3 4 5% 61%	3898
	21st to end	Night	5% 3 1 4 2 3 4 4 6% 8% 60%	4299
November	1st to 10th	Night	4 7% 2 5% 3 3 4 4 6% 7% 55%	2665
	11th to 20th	Night	3 5% 2 6% 4 4 5% 4 6% 7% 55%	2730
	21st to end	Night	3 7% 3 7% 5% 4 4 3 5% 7% 51%	2730
December	1st to 10th	Night	2 5% 1 5% 3 3 4 3 4 7% 62%	4370
	11th to 20th	Night	3 7% 2 7% 5% 4 4 4 7% 10% 47%	4941
	21st to end	Night	3 8% 4 11% 6% 6% 6% 5% 7% 8% 37%	6611

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	38% 13% 20% 19% 9%	5321
	11th to 20th	Day	29% 8% 13% 27% 18% 5%	5340
	21st to end	Day	31% 7% 15% 19% 23% 4	5844
February	1st to 10th	Day	42% 7% 16% 21% 13% 2	1890
	11th to 20th	Day	40% 9% 15% 21% 13% 2	1985
	21st to end	Day	34% 7% 15% 26% 14% 3	1730
March	1st to 10th	Day	33% 9% 12% 22% 17% 6%	4882
	11th to 20th	Day	30% 10% 14% 27% 16% 3	5110
	21st to end	Day	40% 12% 17% 20% 11% 1	5607
April	1st to 10th	Day	34% 7% 11% 22% 19% 7%	2310
	11th to 20th	Day	34% 7% 10% 20% 22% 7%	2668
	21st to end	Day	30% 6% 11% 24% 25% 5%	2730
May	1st to 10th	Day	24% 8% 11% 18% 28% 11%	7626
	11th to 20th	Day	23% 7% 9% 18% 32% 11%	7599
	21st to end	Day	23% 8% 8% 19% 34% 8%	8371
June	1st to 10th	Day	20% 5% 9% 17% 33% 16%	2730
	11th to 20th	Day	18% 4 6% 13% 30% 30%	2730
	21st to end	Day	15% 2 4 10% 27% 41%	2730
July	1st to 10th	Day	13% 3 3 4 16% 60%	7586
	11th to 20th	Day	22% 7% 9% 12% 19% 31%	7581
	21st to end	Day	15% 5% 6% 13% 20% 39%	8120
August	1st to 10th	Day	16% 4 6% 14% 23% 37%	5978
	11th to 20th	Day	20% 6% 7% 20% 24% 23%	5964
	21st to end	Day	17% 5% 8% 21% 23% 27%	6551
September	1st to 10th	Day	15% 4 7% 12% 28% 34%	2310
	11th to 20th	Day	17% 4 7% 18% 28% 26%	2234
	21st to end	Day	16% 4 6% 18% 32% 25%	2200
October	1st to 10th	Day	18% 3 5% 11% 37% 25%	3485
	11th to 20th	Day	22% 5% 6% 26% 30% 12%	3250
	21st to end	Day	22% 4 7% 27% 32% 7%	3496
November	1st to 10th	Day	28% 6% 12% 24% 22% 8%	1854
	11th to 20th	Day	29% 7% 12% 29% 20% 2	1890
	21st to end	Day	33% 6% 14% 26% 18% 3	1890
December	1st to 10th	Day	23% 4 12% 40% 20% 2	3040
	11th to 20th	Day	33% 8% 17% 25% 16% 1	3498
	21st to end	Day	41% 11% 14% 17% 16% 1	4609
January	1st to 10th	Night	34% 13% 21% 19% 13% 1	7605
	11th to 20th	Night	26% 10% 12% 25% 21% 6%	7650
	21st to end	Night	28% 8% 16% 21% 26% 3	8370
February	1st to 10th	Night	35% 8% 17% 25% 11% 3	2730
	11th to 20th	Night	37% 7% 12% 24% 17% 3	2531
	21st to end	Night	32% 7% 13% 28% 16% 4	2076
March	1st to 10th	Night	34% 10% 10% 22% 17% 7%	5231
	11th to 20th	Night	28% 9% 14% 27% 19% 3	5110
	21st to end	Night	31% 8% 17% 23% 19% 2	5610
April	1st to 10th	Night	31% 5% 11% 24% 21% 8%	2310
	11th to 20th	Night	30% 5% 11% 25% 23% 6%	1897
	21st to end	Night	30% 6% 13% 24% 23% 4	1890
May	1st to 10th	Night	25% 7% 10% 17% 31% 10%	5319
	11th to 20th	Night	19% 6% 7% 19% 36% 13%	5297
	21st to end	Night	24% 6% 7% 20% 38% 5%	5838
June	1st to 10th	Night	22% 5% 9% 18% 31% 16%	1890
	11th to 20th	Night	17% 5% 6% 14% 29% 29%	1890
	21st to end	Night	17% 5% 5% 9% 24% 39%	1890
July	1st to 10th	Night	19% 4 3 5% 13% 56%	5295
	11th to 20th	Night	30% 6% 8% 9% 14% 31%	5286
	21st to end	Night	22% 5% 6% 10% 19% 37%	5677
August	1st to 10th	Night	21% 4 7% 11% 19% 38%	4168
	11th to 20th	Night	26% 5% 9% 18% 21% 21%	4168
	21st to end	Night	22% 6% 10% 15% 19% 28%	4593
September	1st to 10th	Night	16% 3 6% 14% 25% 35%	2309
	11th to 20th	Night	18% 5% 7% 17% 26% 28%	2233
	21st to end	Night	18% 3 5% 15% 31% 29%	2200
October	1st to 10th	Night	15% 3 6% 12% 34% 30%	3710
	11th to 20th	Night	24% 4 6% 24% 30% 13%	3898
	21st to end	Night	20% 4 7% 28% 35% 7%	4299
November	1st to 10th	Night	27% 6% 9% 26% 24% 8%	2665
	11th to 20th	Night	25% 6% 13% 30% 22% 3	2730
	21st to end	Night	31% 4 11% 27% 23% 4	2730
December	1st to 10th	Night	21% 5% 10% 38% 24% 3	4370
	11th to 20th	Night	29% 7% 18% 28% 16% 2	4941
	21st to end	Night	38% 9% 16% 21% 15% 1	6611

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	13% 15% 28% 25% 16% 4	330
	11th to 20th	Day	6% 14% 27% 31% 15% 8%	330
	21st to end	Day	5% 12% 27% 34% 18% 4	363
February	1st to 10th	Day	11% 23% 26% 22% 14% 4	330
	11th to 20th	Day	9% 19% 34% 25% 10% 2	461
	21st to end	Day	8% 14% 37% 27% 11% 3	446
March	1st to 10th	Day	13% 16% 31% 26% 12% 2	540
	11th to 20th	Day	11% 19% 31% 24% 12% 3	540
	21st to end	Day	14% 22% 32% 20% 10% 2	594
April	1st to 10th	Day	12% 19% 30% 22% 13% 4	540
	11th to 20th	Day	16% 25% 27% 20% 10% 2	532
	21st to end	Day	15% 20% 29% 23% 10% 2	540
May	1st to 10th	Day	13% 17% 33% 22% 12% 4	543
	11th to 20th	Day	11% 17% 29% 26% 13% 4	568
	21st to end	Day	10% 12% 28% 27% 18% 6%	617
June	1st to 10th	Day	4 12% 30% 27% 20% 6%	570
	11th to 20th	Day	6% 16% 32% 28% 14% 5%	570
	21st to end	Day	4 9% 31% 36% 15% 4	570
July	1st to 10th	Day	2 6% 29% 39% 18% 6%	566
	11th to 20th	Day	4 4 24% 38% 22% 8%	564
	21st to end	Day	3 5% 20% 39% 23% 10%	619
August	1st to 10th	Day	4 6% 27% 36% 19% 8%	567
	11th to 20th	Day	5% 6% 23% 36% 20% 10%	557
	21st to end	Day	4 7% 24% 30% 25% 9%	627
September	1st to 10th	Day	5% 9% 25% 26% 22% 13%	570
	11th to 20th	Day	5% 12% 25% 29% 20% 8%	543
	21st to end	Day	4 12% 22% 29% 23% 8%	530
October	1st to 10th	Day	7% 13% 24% 24% 22% 9%	467
	11th to 20th	Day	6% 15% 23% 22% 22% 12%	330
	21st to end	Day	9% 13% 25% 25% 22% 5%	363
November	1st to 10th	Day	9% 14% 26% 28% 12% 11%	330
	11th to 20th	Day	6% 14% 28% 26% 18% 8%	330
	21st to end	Day	9% 12% 22% 28% 22% 7%	330
December	1st to 10th	Day	7% 11% 22% 37% 16% 6%	330
	11th to 20th	Day	8% 11% 28% 30% 17% 6%	330
	21st to end	Day	15% 13% 28% 29% 13% 2	363
January	1st to 10th	Night	9% 10% 18% 34% 23% 6%	840
	11th to 20th	Night	7% 8% 19% 36% 24% 5%	840
	21st to end	Night	8% 7% 20% 38% 22% 6%	924
February	1st to 10th	Night	7% 10% 24% 36% 18% 4	840
	11th to 20th	Night	8% 7% 25% 38% 19% 2	824
	21st to end	Night	6% 8% 25% 42% 17% 1	692
March	1st to 10th	Night	10% 11% 23% 38% 16% 3	840
	11th to 20th	Night	7% 10% 22% 38% 21% 2	840
	21st to end	Night	9% 12% 25% 37% 15% 2	924
April	1st to 10th	Night	10% 15% 20% 36% 18% 3	840
	11th to 20th	Night	9% 14% 27% 35% 14% 2	644
	21st to end	Night	11% 10% 22% 38% 16% 3	630
May	1st to 10th	Night	10% 7% 25% 37% 18% 3	630
	11th to 20th	Night	8% 7% 18% 39% 24% 4	621
	21st to end	Night	11% 7% 16% 36% 25% 5%	683
June	1st to 10th	Night	7% 8% 17% 37% 29% 2	630
	11th to 20th	Night	6% 11% 19% 38% 24% 1	630
	21st to end	Night	4 3 20% 40% 30% 3	630
July	1st to 10th	Night	4 3 17% 39% 32% 5%	615
	11th to 20th	Night	7% 3 11% 42% 32% 5%	612
	21st to end	Night	5% 2 10% 37% 42% 4	690
August	1st to 10th	Night	6% 2 17% 39% 33% 3	627
	11th to 20th	Night	3 1 16% 43% 32% 4	624
	21st to end	Night	3 4 14% 42% 32% 6%	695
September	1st to 10th	Night	4 4 13% 35% 36% 8%	840
	11th to 20th	Night	4 5% 15% 37% 32% 9%	812
	21st to end	Night	5% 5% 13% 34% 32% 11%	800
October	1st to 10th	Night	7% 5% 16% 37% 27% 8%	800
	11th to 20th	Night	7% 5% 14% 39% 28% 8%	800
	21st to end	Night	7% 7% 17% 33% 30% 6%	880
November	1st to 10th	Night	9% 8% 14% 34% 27% 8%	820
	11th to 20th	Night	6% 7% 19% 41% 22% 5%	840
	21st to end	Night	7% 10% 17% 33% 24% 9%	840
December	1st to 10th	Night	8% 7% 19% 40% 22% 5%	840
	11th to 20th	Night	12% 7% 17% 38% 23% 2	840
	21st to end	Night	12% 11% 22% 36% 17% 2	924

Page generated at 2026-09-11 02:11:51. Version ac07

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