Woodland Altars Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woodland Altars Campground clear sky chart from 2005-11-06 to 2026-03-03.

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% 9% 3 7% 5% 4 4 4 5% 7% 35%	131180
	Night	15% 10% 4 8% 5% 4 4 3 5% 7% 36%	130023
Transparency	Day	47% 6% 11% 22% 13% 2	134841
	Night	47% 5% 11% 21% 14% 2	134431
Seeing	Day	22% 14% 27% 21% 12% 5%	16497
	Night	20% 12% 25% 27% 15% 2	26649

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	18% 18% 6% 11% 5% 4 3 3 4 5% 22%	5258
	11th to 20th	Day	14% 16% 7% 15% 5% 5% 4 2 3 4 28%	5280
	21st to end	Day	20% 13% 6% 9% 7% 6% 5% 3 5% 5% 21%	5780
February	1st to 10th	Day	20% 13% 5% 8% 4 4 4 3 4 5% 29%	1932
	11th to 20th	Day	19% 13% 4 10% 6% 4 4 3 5% 5% 28%	2048
	21st to end	Day	19% 14% 5% 8% 4 3 3 2 4 6% 32%	1730
March	1st to 10th	Day	17% 15% 5% 9% 5% 4 3 3 4 4 31%	4674
	11th to 20th	Day	14% 8% 3 7% 4 4 4 4 6% 7% 40%	4980
	21st to end	Day	19% 9% 3 7% 5% 4 4 3 5% 7% 34%	5465
April	1st to 10th	Day	15% 11% 3 7% 4 4 4 3 5% 6% 36%	2269
	11th to 20th	Day	18% 9% 3 6% 4 4 3 3 5% 7% 38%	2483
	21st to end	Day	18% 7% 3 7% 6% 6% 4 3 5% 6% 35%	2600
May	1st to 10th	Day	20% 9% 3 7% 5% 5% 5% 4 6% 7% 29%	5862
	11th to 20th	Day	21% 9% 3 7% 4 4 4 4 5% 7% 31%	5861
	21st to end	Day	16% 6% 3 8% 5% 5% 5% 4 7% 8% 33%	6433
June	1st to 10th	Day	12% 5% 2 6% 5% 5% 5% 5% 7% 9% 39%	2600
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 5% 6% 9% 40%	2600
	21st to end	Day	10% 5% 2 6% 5% 5% 6% 5% 7% 9% 40%	2600
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 4 4 6% 8% 42%	5900
	11th to 20th	Day	11% 7% 2 6% 5% 6% 6% 5% 7% 11% 34%	5900
	21st to end	Day	12% 7% 3 8% 6% 5% 6% 5% 7% 9% 32%	6424
August	1st to 10th	Day	8% 5% 2 7% 4 5% 5% 5% 8% 11% 40%	4234
	11th to 20th	Day	8% 6% 2 6% 5% 5% 5% 5% 8% 10% 40%	4174
	21st to end	Day	6% 3 1 5% 4 4 4 4 6% 8% 55%	4486
September	1st to 10th	Day	14% 5% 2 4 4 4 4 3 5% 6% 48%	2220
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 5% 7% 51%	2200
	21st to end	Day	19% 6% 3 6% 4 3 4 3 5% 5% 44%	2200
October	1st to 10th	Day	13% 5% 2 4 3 3 5% 4 5% 7% 48%	2176
	11th to 20th	Day	14% 8% 2 5% 3 3 4 3 4 7% 47%	2000
	21st to end	Day	21% 9% 2 6% 4 3 3 3 4 6% 40%	2131
November	1st to 10th	Day	12% 8% 2 5% 4 3 3 4 5% 6% 49%	1852
	11th to 20th	Day	16% 13% 4 6% 4 3 3 3 5% 6% 37%	1890
	21st to end	Day	18% 12% 4 7% 4 4 3 3 4 5% 35%	1890
December	1st to 10th	Day	19% 13% 4 9% 5% 5% 4 3 4 4 31%	3020
	11th to 20th	Day	22% 14% 6% 8% 4 5% 5% 3 5% 5% 24%	3463
	21st to end	Day	21% 19% 5% 11% 5% 4 4 3 4 5% 20%	4565
January	1st to 10th	Night	15% 16% 6% 14% 7% 5% 5% 3 5% 5% 20%	7635
	11th to 20th	Night	13% 16% 7% 15% 7% 4 4 3 4 4 24%	7680
	21st to end	Night	18% 12% 5% 9% 6% 5% 4 2 4 4 31%	8401
February	1st to 10th	Night	20% 14% 4 8% 6% 3 3 3 4 5% 29%	2686
	11th to 20th	Night	20% 13% 3 9% 5% 4 4 3 4 6% 30%	2458
	21st to end	Night	21% 15% 4 7% 4 4 3 3 4 5% 30%	2076
March	1st to 10th	Night	18% 13% 3 6% 4 4 4 3 4 5% 37%	5224
	11th to 20th	Night	13% 9% 3 5% 3 3 4 4 6% 9% 42%	4980
	21st to end	Night	17% 10% 3 8% 6% 5% 4 3 5% 6% 33%	5467
April	1st to 10th	Night	16% 9% 2 6% 5% 5% 4 4 5% 7% 36%	2148
	11th to 20th	Night	14% 8% 2 6% 4 5% 4 4 6% 6% 41%	1864
	21st to end	Night	17% 7% 3 6% 5% 4 4 4 6% 8% 37%	1800
May	1st to 10th	Night	24% 9% 3 7% 5% 4 5% 3 5% 7% 29%	4033
	11th to 20th	Night	18% 7% 3 5% 4 4 5% 4 7% 9% 34%	4032
	21st to end	Night	15% 6% 3 6% 4 4 5% 4 6% 9% 37%	4421
June	1st to 10th	Night	8% 5% 2 5% 4 5% 5% 4 5% 9% 47%	1800
	11th to 20th	Night	9% 4 2 5% 4 4 5% 4 6% 11% 46%	1800
	21st to end	Night	8% 4 2 5% 4 3 6% 4 9% 10% 45%	1800
July	1st to 10th	Night	10% 6% 2 5% 4 5% 5% 4 6% 8% 46%	4058
	11th to 20th	Night	11% 6% 2 7% 5% 4 4 4 7% 10% 39%	4057
	21st to end	Night	9% 7% 3 8% 5% 6% 5% 5% 7% 8% 39%	4427
August	1st to 10th	Night	7% 6% 2 6% 5% 5% 4 4 7% 9% 45%	2915
	11th to 20th	Night	10% 7% 3 7% 4 5% 4 4 5% 8% 43%	2875
	21st to end	Night	4 3 2 4 3 3 5% 4 7% 10% 57%	3408
September	1st to 10th	Night	12% 5% 2 5% 4 3 3 3 4 7% 52%	2160
	11th to 20th	Night	9% 4 2 4 4 4 4 4 5% 7% 54%	2200
	21st to end	Night	14% 5% 2 6% 4 4 4 3 5% 5% 47%	2200
October	1st to 10th	Night	9% 5% 2 6% 3 3 3 3 5% 6% 54%	2222
	11th to 20th	Night	15% 7% 2 4 4 4 4 3 5% 7% 47%	2400
	21st to end	Night	20% 8% 2 5% 4 4 4 3 4 5% 42%	2705
November	1st to 10th	Night	14% 7% 2 5% 4 3 4 3 4 6% 48%	2666
	11th to 20th	Night	16% 11% 3 5% 5% 4 3 3 4 6% 39%	2730
	21st to end	Night	20% 13% 3 6% 5% 4 3 3 4 6% 32%	2730
December	1st to 10th	Night	19% 12% 4 7% 4 3 3 2 3 5% 36%	4380
	11th to 20th	Night	20% 15% 7% 8% 4 4 4 3 4 5% 27%	4952
	21st to end	Night	22% 19% 6% 9% 5% 4 4 3 4 5% 18%	6633

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	64% 4 12% 15% 5%	5259
	11th to 20th	Day	61% 4 7% 15% 11% 2	5280
	21st to end	Day	66% 3 8% 15% 7% 1	5780
February	1st to 10th	Day	58% 5% 11% 17% 9% 1	1932
	11th to 20th	Day	57% 5% 10% 17% 10% 1	2058
	21st to end	Day	55% 4 10% 21% 9% 2	1730
March	1st to 10th	Day	54% 5% 7% 20% 11% 3	4674
	11th to 20th	Day	41% 6% 9% 26% 15% 2	4980
	21st to end	Day	49% 6% 10% 21% 12% 2	5465
April	1st to 10th	Day	46% 7% 11% 22% 11% 2	2269
	11th to 20th	Day	45% 6% 10% 22% 14% 3	2483
	21st to end	Day	48% 7% 11% 20% 11% 2	2600
May	1st to 10th	Day	53% 6% 12% 18% 10% 1	5897
	11th to 20th	Day	51% 7% 11% 22% 10% 1	5865
	21st to end	Day	43% 9% 14% 19% 13% 2	6447
June	1st to 10th	Day	38% 9% 14% 22% 16% 2	2600
	11th to 20th	Day	38% 9% 15% 21% 16% 1	2600
	21st to end	Day	37% 9% 14% 23% 13% 3	2600
July	1st to 10th	Day	40% 5% 12% 25% 17% 1	5835
	11th to 20th	Day	42% 6% 14% 25% 12% 1	5831
	21st to end	Day	48% 5% 14% 18% 13% 2	6240
August	1st to 10th	Day	35% 7% 14% 32% 10% 1	4221
	11th to 20th	Day	36% 6% 12% 29% 16% 1	4213
	21st to end	Day	26% 6% 15% 29% 21% 3	4485
September	1st to 10th	Day	35% 6% 11% 22% 19% 5%	2220
	11th to 20th	Day	32% 7% 12% 23% 24% 3	2200
	21st to end	Day	42% 5% 10% 22% 20% 2	2200
October	1st to 10th	Day	23% 4 9% 30% 32% 2	3540
	11th to 20th	Day	30% 4 9% 30% 26% 2	3240
	21st to end	Day	36% 3 10% 26% 22% 3	3420
November	1st to 10th	Day	36% 5% 11% 26% 19% 2	1852
	11th to 20th	Day	48% 4 9% 21% 15% 3	1890
	21st to end	Day	51% 5% 10% 20% 13% 1	1890
December	1st to 10th	Day	56% 4 9% 23% 7%	3020
	11th to 20th	Day	61% 6% 9% 18% 6%	3460
	21st to end	Day	67% 5% 9% 12% 6% 1	4565
January	1st to 10th	Night	66% 5% 8% 14% 6%	7636
	11th to 20th	Night	64% 4 6% 13% 10% 2	7680
	21st to end	Night	57% 4 10% 19% 9% 1	8401
February	1st to 10th	Night	58% 5% 10% 18% 8% 1	2686
	11th to 20th	Night	57% 4 8% 19% 11% 1	2459
	21st to end	Night	58% 4 11% 15% 10% 3	2076
March	1st to 10th	Night	49% 5% 7% 26% 12% 2	5224
	11th to 20th	Night	38% 6% 10% 30% 17% 1	4980
	21st to end	Night	51% 6% 8% 22% 12% 1	5467
April	1st to 10th	Night	45% 7% 11% 22% 14% 2	2148
	11th to 20th	Night	41% 7% 11% 19% 17% 5%	1864
	21st to end	Night	45% 7% 11% 21% 14% 2	1800
May	1st to 10th	Night	54% 7% 11% 17% 8% 3	4060
	11th to 20th	Night	46% 9% 14% 22% 9% 1	4033
	21st to end	Night	40% 8% 17% 21% 10% 3	4429
June	1st to 10th	Night	32% 8% 13% 24% 20% 2	1800
	11th to 20th	Night	31% 9% 16% 20% 21% 3	1800
	21st to end	Night	30% 10% 17% 24% 16% 3	1800
July	1st to 10th	Night	37% 5% 12% 24% 19% 3	4015
	11th to 20th	Night	39% 7% 16% 24% 13% 1	4006
	21st to end	Night	41% 6% 14% 23% 13% 3	4297
August	1st to 10th	Night	35% 6% 15% 32% 11% 1	2904
	11th to 20th	Night	39% 6% 10% 25% 18% 1	2902
	21st to end	Night	22% 6% 17% 30% 22% 3	3408
September	1st to 10th	Night	31% 6% 13% 23% 20% 6%	2160
	11th to 20th	Night	28% 8% 11% 23% 28% 3	2200
	21st to end	Night	38% 6% 10% 20% 26% 1	2200
October	1st to 10th	Night	24% 5% 8% 25% 36% 3	3638
	11th to 20th	Night	28% 4 8% 26% 29% 5%	3899
	21st to end	Night	34% 3 9% 22% 26% 7%	4366
November	1st to 10th	Night	37% 3 11% 24% 22% 3	2666
	11th to 20th	Night	46% 4 8% 21% 18% 3	2730
	21st to end	Night	53% 5% 10% 20% 11% 1	2730
December	1st to 10th	Night	53% 3 11% 24% 8% 1	4380
	11th to 20th	Night	59% 4 11% 18% 7%	4954
	21st to end	Night	68% 5% 9% 14% 4	6633

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	33% 22% 30% 12% 3	330
	11th to 20th	Day	37% 26% 29% 6% 1	330
	21st to end	Day	36% 25% 26% 10% 2	363
February	1st to 10th	Day	31% 25% 31% 12% 2	330
	11th to 20th	Day	38% 27% 30% 4 1	330
	21st to end	Day	36% 23% 35% 5% 1	273
March	1st to 10th	Day	32% 24% 27% 14% 3	376
	11th to 20th	Day	28% 23% 31% 13% 4	500
	21st to end	Day	35% 20% 27% 15% 3	550
April	1st to 10th	Day	27% 20% 29% 14% 8% 1	500
	11th to 20th	Day	27% 21% 27% 13% 9% 2	492
	21st to end	Day	27% 16% 34% 14% 7% 2	500
May	1st to 10th	Day	28% 17% 30% 16% 7% 2	503
	11th to 20th	Day	23% 11% 32% 20% 11% 4	527
	21st to end	Day	17% 11% 26% 26% 15% 5%	573
June	1st to 10th	Day	15% 11% 25% 29% 15% 6%	530
	11th to 20th	Day	14% 8% 25% 31% 16% 6%	530
	21st to end	Day	11% 9% 30% 25% 16% 8%	530
July	1st to 10th	Day	16% 6% 18% 23% 18% 19%	525
	11th to 20th	Day	10% 6% 24% 29% 21% 10%	524
	21st to end	Day	13% 2 22% 30% 19% 14%	576
August	1st to 10th	Day	10% 4 20% 30% 23% 13%	526
	11th to 20th	Day	12% 5% 20% 33% 20% 9%	519
	21st to end	Day	9% 5% 19% 33% 24% 11%	583
September	1st to 10th	Day	13% 5% 18% 28% 25% 11%	530
	11th to 20th	Day	10% 2 18% 27% 31% 12%	530
	21st to end	Day	23% 8% 19% 25% 21% 4	530
October	1st to 10th	Day	13% 7% 25% 31% 17% 7%	530
	11th to 20th	Day	19% 13% 33% 19% 11% 5%	530
	21st to end	Day	26% 17% 31% 21% 6%	514
November	1st to 10th	Day	19% 19% 34% 19% 7% 2	330
	11th to 20th	Day	32% 16% 32% 16% 3 2	330
	21st to end	Day	30% 22% 33% 12% 2	330
December	1st to 10th	Day	33% 19% 34% 10% 5%	330
	11th to 20th	Day	29% 24% 34% 11% 3	330
	21st to end	Day	36% 21% 28% 12% 3	363
January	1st to 10th	Night	29% 20% 28% 18% 4	840
	11th to 20th	Night	31% 22% 29% 16% 2	840
	21st to end	Night	27% 21% 31% 20% 2	924
February	1st to 10th	Night	31% 16% 30% 21% 2	840
	11th to 20th	Night	31% 22% 29% 17% 1	823
	21st to end	Night	30% 18% 32% 19% 1	692
March	1st to 10th	Night	24% 19% 28% 24% 4	809
	11th to 20th	Night	25% 18% 30% 20% 7%	800
	21st to end	Night	24% 14% 31% 24% 7%	880
April	1st to 10th	Night	22% 15% 33% 22% 7%	748
	11th to 20th	Night	17% 13% 34% 23% 11% 1	593
	21st to end	Night	21% 11% 35% 27% 6% 1	600
May	1st to 10th	Night	22% 10% 29% 26% 11% 1	600
	11th to 20th	Night	19% 9% 25% 28% 18% 1	591
	21st to end	Night	9% 5% 24% 32% 26% 4	650
June	1st to 10th	Night	10% 3 24% 39% 22% 2	600
	11th to 20th	Night	10% 4 19% 38% 25% 4	600
	21st to end	Night	8% 4 24% 34% 27% 4	600
July	1st to 10th	Night	14% 1 13% 31% 31% 9%	585
	11th to 20th	Night	7% 2 17% 36% 33% 5%	582
	21st to end	Night	9% 3 13% 35% 36% 4	657
August	1st to 10th	Night	8% 2 12% 40% 33% 5%	597
	11th to 20th	Night	8% 3 12% 39% 32% 7%	594
	21st to end	Night	8% 1 17% 35% 33% 7%	660
September	1st to 10th	Night	13% 4 14% 32% 32% 6%	760
	11th to 20th	Night	10% 4 14% 32% 34% 7%	800
	21st to end	Night	15% 7% 18% 34% 24% 2	800
October	1st to 10th	Night	12% 6% 22% 32% 24% 4	800
	11th to 20th	Night	18% 11% 25% 31% 14% 1	800
	21st to end	Night	24% 13% 26% 26% 10% 1	880
November	1st to 10th	Night	19% 10% 25% 28% 16% 1	820
	11th to 20th	Night	24% 17% 25% 24% 9% 1	840
	21st to end	Night	29% 14% 25% 25% 7% 1	840
December	1st to 10th	Night	31% 17% 28% 20% 5%	840
	11th to 20th	Night	28% 15% 29% 22% 5% 1	840
	21st to end	Night	30% 18% 27% 22% 3	924

Page generated at 2026-02-28 01:40:23. Version ac07

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