ScrubGrass Campgrounds
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the ScrubGrass Campgrounds clear sky chart from 2005-11-06 to 2026-01-02.

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	12% 6% 2 6% 4 4 4 4 5% 7% 45%	126311
	Night	13% 6% 2 5% 4 3 4 3 5% 7% 49%	125221
Transparency	Day	24% 38% 6% 16% 12% 3	129918
	Night	23% 37% 6% 15% 14% 5%	129691
Seeing	Day	13% 8% 21% 25% 23% 10%	16793
	Night	14% 7% 23% 32% 21% 3	26590

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	17% 11% 4 8% 3 2 2 2 3 3 46%	4086
	11th to 20th	Day	17% 6% 2 6% 3 2 3 2 4 4 51%	4080
	21st to end	Day	20% 7% 3 5% 3 2 2 2 3 5% 48%	4488
February	1st to 10th	Day	21% 8% 3 5% 4 3 4 3 4 5% 41%	1877
	11th to 20th	Day	21% 9% 3 7% 3 3 3 2 3 5% 41%	1948
	21st to end	Day	21% 9% 3 7% 4 3 3 3 4 6% 39%	1650
March	1st to 10th	Day	20% 12% 3 9% 4 4 3 3 3 5% 34%	4797
	11th to 20th	Day	11% 5% 2 6% 4 3 4 3 4 6% 50%	4980
	21st to end	Day	12% 7% 3 9% 5% 4 4 3 5% 6% 41%	5640
April	1st to 10th	Day	14% 5% 3 6% 4 4 4 4 6% 7% 44%	2400
	11th to 20th	Day	14% 6% 2 6% 3 3 3 4 5% 7% 46%	2374
	21st to end	Day	11% 6% 3 7% 6% 5% 4 3 5% 6% 43%	2400
May	1st to 10th	Day	16% 8% 3 7% 5% 5% 4 4 5% 7% 38%	5405
	11th to 20th	Day	12% 7% 3 8% 6% 5% 5% 4 7% 9% 36%	5404
	21st to end	Day	13% 6% 2 7% 6% 5% 5% 5% 7% 8% 35%	6723
June	1st to 10th	Day	8% 5% 2 6% 5% 5% 6% 4 6% 9% 43%	2800
	11th to 20th	Day	6% 4 2 6% 5% 5% 5% 4 6% 10% 47%	2800
	21st to end	Day	4 4 2 5% 5% 4 5% 5% 7% 10% 50%	2800
July	1st to 10th	Day	6% 5% 2 7% 5% 6% 7% 6% 9% 10% 38%	5953
	11th to 20th	Day	6% 4 2 6% 4 5% 6% 5% 9% 12% 42%	5900
	21st to end	Day	10% 6% 2 6% 4 5% 5% 4 7% 9% 41%	6422
August	1st to 10th	Day	3 2 1 4 3 3 4 3 6% 8% 64%	4018
	11th to 20th	Day	6% 3 2 6% 5% 5% 6% 5% 7% 10% 46%	3849
	21st to end	Day	7% 4 2 5% 5% 4 6% 4 6% 8% 50%	4312
September	1st to 10th	Day	8% 5% 2 6% 4 6% 6% 4 6% 8% 46%	2400
	11th to 20th	Day	11% 5% 3 6% 4 4 4 5% 5% 7% 47%	2400
	21st to end	Day	10% 4 2 4 4 3 4 3 5% 7% 54%	2165
October	1st to 10th	Day	7% 3 1 4 3 3 3 4 5% 7% 59%	2000
	11th to 20th	Day	11% 4 2 5% 2 2 2 2 4 6% 60%	2000
	21st to end	Day	18% 6% 2 4 2 3 3 3 4 4 52%	2200
November	1st to 10th	Day	14% 4 2 4 3 3 3 2 3 5% 57%	2058
	11th to 20th	Day	11% 5% 2 4 4 3 3 3 3 6% 54%	1895
	21st to end	Day	18% 7% 2 6% 3 3 3 2 5% 6% 45%	1890
December	1st to 10th	Day	18% 8% 3 5% 4 3 3 3 3 5% 45%	2898
	11th to 20th	Day	20% 9% 3 6% 3 3 3 2 3 6% 42%	3088
	21st to end	Day	15% 7% 3 7% 5% 4 5% 3 5% 5% 43%	4211
January	1st to 10th	Night	17% 7% 2 6% 4 3 3 2 3 4 49%	5902
	11th to 20th	Night	16% 5% 2 4 3 3 3 2 3 3 55%	5900
	21st to end	Night	23% 8% 2 5% 2 2 2 2 4 5% 43%	6490
February	1st to 10th	Night	21% 7% 2 6% 3 4 3 2 4 4 43%	2520
	11th to 20th	Night	20% 8% 2 5% 3 3 4 3 4 5% 43%	2338
	21st to end	Night	21% 7% 2 6% 4 3 4 2 3 5% 43%	1980
March	1st to 10th	Night	17% 8% 3 7% 4 4 4 2 4 5% 42%	5097
	11th to 20th	Night	12% 5% 2 5% 4 3 4 4 5% 7% 49%	4980
	21st to end	Night	14% 7% 2 7% 5% 3 4 3 5% 6% 44%	5289
April	1st to 10th	Night	13% 5% 3 6% 4 4 4 4 5% 7% 48%	2000
	11th to 20th	Night	13% 5% 2 5% 4 3 3 4 5% 7% 49%	1975
	21st to end	Night	11% 5% 3 5% 5% 3 4 3 5% 6% 49%	2000
May	1st to 10th	Night	18% 8% 3 6% 4 4 4 3 6% 7% 38%	4490
	11th to 20th	Night	18% 9% 3 8% 4 4 4 4 5% 6% 35%	4489
	21st to end	Night	11% 7% 3 7% 5% 5% 5% 3 6% 8% 41%	4117
June	1st to 10th	Night	5% 4 2 5% 5% 4 5% 3 7% 11% 50%	1600
	11th to 20th	Night	4 4 2 5% 3 3 4 5% 7% 10% 54%	1600
	21st to end	Night	4 3 2 4 4 5% 5% 4 6% 9% 57%	1600
July	1st to 10th	Night	4 4 2 6% 5% 4 5% 5% 9% 11% 44%	4019
	11th to 20th	Night	5% 3 2 4 3 4 5% 5% 8% 13% 49%	4077
	21st to end	Night	9% 6% 2 5% 3 4 4 4 7% 11% 45%	4449
August	1st to 10th	Night	2 2 1 2 2 2 2 3 5% 7% 72%	3132
	11th to 20th	Night	4 4 1 4 3 4 5% 4 6% 11% 55%	3200
	21st to end	Night	5% 4 2 5% 4 4 4 4 5% 8% 54%	3586
September	1st to 10th	Night	8% 5% 2 5% 5% 4 4 3 4 6% 53%	2000
	11th to 20th	Night	11% 5% 2 5% 4 3 5% 4 5% 6% 51%	2000
	21st to end	Night	8% 5% 2 4 3 2 3 3 5% 7% 58%	2209
October	1st to 10th	Night	7% 2 1 4 2 3 2 3 4 6% 66%	2400
	11th to 20th	Night	10% 4 2 4 2 3 3 2 5% 5% 61%	2400
	21st to end	Night	15% 5% 1 5% 2 2 3 3 3 5% 55%	2640
November	1st to 10th	Night	11% 5% 2 4 4 3 3 2 4 5% 56%	2460
	11th to 20th	Night	10% 4 2 4 3 3 3 2 4 6% 57%	2722
	21st to end	Night	14% 5% 2 5% 4 3 3 3 4 5% 51%	2730
December	1st to 10th	Night	17% 7% 2 5% 3 2 3 3 4 5% 49%	4500
	11th to 20th	Night	18% 8% 2 6% 4 4 3 2 3 4 47%	5339
	21st to end	Night	17% 7% 2 6% 4 4 4 3 5% 5% 43%	6991

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	35% 26% 3 21% 13% 1	4087
	11th to 20th	Day	27% 26% 6% 20% 18% 3	4080
	21st to end	Day	30% 28% 3 12% 19% 8%	4488
February	1st to 10th	Day	20% 62% 2 8% 6% 2	1877
	11th to 20th	Day	21% 61% 2 9% 5% 2	1958
	21st to end	Day	20% 61% 3 5% 5% 5%	1650
March	1st to 10th	Day	43% 29% 2 10% 9% 7%	4797
	11th to 20th	Day	22% 29% 4 13% 21% 11%	4980
	21st to end	Day	32% 29% 5% 16% 16% 1	5642
April	1st to 10th	Day	17% 63% 3 9% 7% 2	2400
	11th to 20th	Day	18% 63% 3 9% 6% 2	2374
	21st to end	Day	16% 63% 5% 7% 8% 1	2400
May	1st to 10th	Day	32% 30% 6% 22% 8% 1	5440
	11th to 20th	Day	33% 31% 11% 16% 8% 1	5408
	21st to end	Day	34% 31% 9% 15% 10% 2	6737
June	1st to 10th	Day	14% 63% 5% 9% 8% 1	2800
	11th to 20th	Day	14% 63% 7% 10% 5% 1	2800
	21st to end	Day	11% 62% 7% 15% 5%	2800
July	1st to 10th	Day	27% 30% 13% 19% 10% 1	5889
	11th to 20th	Day	23% 29% 17% 27% 4	5831
	21st to end	Day	28% 27% 12% 26% 6%	6240
August	1st to 10th	Day	7% 37% 10% 23% 21% 2	4004
	11th to 20th	Day	19% 39% 13% 24% 6%	3885
	21st to end	Day	20% 37% 6% 17% 18% 1	4311
September	1st to 10th	Day	13% 58% 7% 12% 8% 2	2400
	11th to 20th	Day	13% 58% 5% 12% 10% 1	2400
	21st to end	Day	15% 58% 6% 11% 8% 2	2165
October	1st to 10th	Day	8% 35% 3 6% 18% 29%	3260
	11th to 20th	Day	7% 35% 2 14% 26% 16%	3240
	21st to end	Day	18% 35% 2 13% 25% 7%	3538
November	1st to 10th	Day	21% 53% 3 7% 13% 3	2058
	11th to 20th	Day	16% 54% 4 10% 12% 5%	1895
	21st to end	Day	20% 54% 3 10% 12% 1	1890
December	1st to 10th	Day	29% 34% 2 20% 14% 2	2898
	11th to 20th	Day	32% 30% 2 16% 17% 4	3085
	21st to end	Day	33% 27% 4 22% 12% 1	4211
January	1st to 10th	Night	31% 26% 4 22% 16% 1	5902
	11th to 20th	Night	25% 26% 3 16% 23% 6%	5900
	21st to end	Night	34% 27% 5% 14% 16% 4	6490
February	1st to 10th	Night	19% 61% 3 7% 8% 2	2520
	11th to 20th	Night	18% 61% 3 10% 5% 3	2339
	21st to end	Night	18% 62% 2 5% 8% 5%	1980
March	1st to 10th	Night	35% 30% 4 9% 14% 9%	5097
	11th to 20th	Night	23% 29% 4 15% 13% 16%	4980
	21st to end	Night	29% 29% 5% 17% 17% 4	5289
April	1st to 10th	Night	15% 62% 4 9% 7% 3	2000
	11th to 20th	Night	16% 63% 3 9% 7% 2	1975
	21st to end	Night	14% 62% 4 8% 10% 2	2000
May	1st to 10th	Night	35% 30% 9% 16% 10% 1	4520
	11th to 20th	Night	40% 30% 7% 17% 6%	4490
	21st to end	Night	34% 30% 9% 14% 10% 4	4125
June	1st to 10th	Night	11% 62% 7% 11% 8% 2	1600
	11th to 20th	Night	11% 64% 8% 9% 7% 1	1600
	21st to end	Night	10% 62% 5% 15% 7%	1600
July	1st to 10th	Night	23% 30% 16% 18% 12% 1	3976
	11th to 20th	Night	18% 29% 16% 30% 6% 1	4026
	21st to end	Night	27% 27% 11% 25% 10%	4320
August	1st to 10th	Night	5% 35% 6% 23% 27% 3	3122
	11th to 20th	Night	12% 38% 15% 24% 10%	3230
	21st to end	Night	18% 37% 5% 15% 22% 3	3586
September	1st to 10th	Night	11% 57% 6% 15% 9% 2	2000
	11th to 20th	Night	12% 58% 4 12% 12% 2	2000
	21st to end	Night	11% 58% 5% 14% 10% 3	2209
October	1st to 10th	Night	6% 36% 4 11% 16% 28%	3920
	11th to 20th	Night	7% 35% 2 11% 23% 23%	3899
	21st to end	Night	14% 35% 3 13% 24% 12%	4252
November	1st to 10th	Night	20% 54% 3 8% 11% 4	2460
	11th to 20th	Night	14% 54% 4 12% 11% 5%	2722
	21st to end	Night	15% 54% 4 12% 13% 3	2730
December	1st to 10th	Night	26% 34% 4 20% 15% 2	4500
	11th to 20th	Night	31% 31% 4 14% 17% 4	5341
	21st to end	Night	32% 28% 6% 18% 14% 2	6991

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% 16% 40% 17% 5% 1	303
	11th to 20th	Day	24% 16% 40% 16% 3 2	300
	21st to end	Day	18% 17% 43% 17% 5%	330
February	1st to 10th	Day	25% 15% 33% 20% 5% 2	300
	11th to 20th	Day	32% 21% 30% 13% 4	300
	21st to end	Day	30% 22% 31% 12% 4	249
March	1st to 10th	Day	23% 17% 34% 17% 8% 1	300
	11th to 20th	Day	18% 22% 35% 22% 3	300
	21st to end	Day	15% 20% 36% 20% 9%	405
April	1st to 10th	Day	19% 13% 35% 25% 7%	500
	11th to 20th	Day	20% 16% 27% 25% 10% 2	492
	21st to end	Day	14% 11% 31% 26% 15% 2	500
May	1st to 10th	Day	15% 13% 25% 30% 15% 2	503
	11th to 20th	Day	14% 6% 25% 24% 24% 7%	527
	21st to end	Day	10% 4 21% 32% 24% 9%	767
June	1st to 10th	Day	9% 4 14% 30% 28% 15%	730
	11th to 20th	Day	5% 3 12% 33% 35% 12%	730
	21st to end	Day	6% 2 10% 32% 33% 19%	730
July	1st to 10th	Day	7% 2 7% 24% 40% 20%	721
	11th to 20th	Day	6% 1 6% 27% 36% 24%	718
	21st to end	Day	6% 3 5% 23% 39% 24%	794
August	1st to 10th	Day	5% 2 8% 25% 42% 19%	601
	11th to 20th	Day	10% 1 7% 21% 41% 19%	519
	21st to end	Day	13% 1 7% 18% 35% 26%	583
September	1st to 10th	Day	8% 2 10% 27% 36% 18%	530
	11th to 20th	Day	11% 2 9% 23% 32% 22%	530
	21st to end	Day	14% 3 14% 25% 30% 14%	495
October	1st to 10th	Day	8% 2 22% 29% 29% 11%	330
	11th to 20th	Day	8% 6% 31% 34% 16% 5%	330
	21st to end	Day	21% 9% 25% 28% 14% 3	363
November	1st to 10th	Day	20% 6% 25% 29% 17% 2	330
	11th to 20th	Day	10% 13% 33% 32% 10% 2	330
	21st to end	Day	22% 14% 28% 21% 12% 3	330
December	1st to 10th	Day	21% 18% 34% 20% 7% 1	330
	11th to 20th	Day	24% 11% 32% 20% 11% 1	330
	21st to end	Day	22% 19% 32% 23% 4 1	363
January	1st to 10th	Night	21% 9% 34% 31% 5%	1006
	11th to 20th	Night	22% 11% 35% 26% 5% 1	1000
	21st to end	Night	20% 10% 38% 29% 3	1100
February	1st to 10th	Night	25% 11% 35% 25% 5%	920
	11th to 20th	Night	23% 13% 33% 28% 3	783
	21st to end	Night	23% 14% 34% 26% 3	660
March	1st to 10th	Night	19% 10% 32% 32% 7%	680
	11th to 20th	Night	19% 10% 33% 31% 8% 1	600
	21st to end	Night	19% 8% 31% 32% 10%	660
April	1st to 10th	Night	15% 10% 34% 33% 8% 1	600
	11th to 20th	Night	15% 10% 30% 33% 11% 1	593
	21st to end	Night	14% 8% 30% 34% 13% 1	600
May	1st to 10th	Night	13% 6% 22% 44% 14% 1	600
	11th to 20th	Night	14% 5% 24% 36% 19% 2	591
	21st to end	Night	7% 3 18% 39% 28% 6%	650
June	1st to 10th	Night	6% 3 11% 39% 36% 6%	600
	11th to 20th	Night	5% 1 9% 38% 41% 6%	600
	21st to end	Night	5% 1 6% 35% 45% 9%	600
July	1st to 10th	Night	4 1 4 32% 49% 9%	585
	11th to 20th	Night	5% 1 4 25% 54% 10%	582
	21st to end	Night	6% 4 29% 50% 11%	657
August	1st to 10th	Night	4 1 4 28% 53% 11%	597
	11th to 20th	Night	6% 2 4 32% 46% 10%	594
	21st to end	Night	10% 1 6% 26% 46% 11%	660
September	1st to 10th	Night	9% 1 9% 34% 40% 7%	600
	11th to 20th	Night	10% 2 9% 30% 42% 7%	600
	21st to end	Night	11% 3 13% 34% 35% 5%	779
October	1st to 10th	Night	8% 2 15% 36% 35% 5%	800
	11th to 20th	Night	11% 5% 21% 43% 19% 1	800
	21st to end	Night	17% 6% 23% 35% 18% 1	880
November	1st to 10th	Night	13% 6% 24% 36% 20% 2	820
	11th to 20th	Night	12% 6% 33% 36% 12% 1	840
	21st to end	Night	15% 8% 31% 32% 12% 2	840
December	1st to 10th	Night	19% 10% 31% 32% 7%	908
	11th to 20th	Night	22% 9% 30% 33% 7%	1050
	21st to end	Night	22% 12% 31% 29% 6%	1155

Page generated at 2025-12-30 00:14:07. Version ac07

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