Juniper Hills Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Juniper Hills Park clear sky chart from 2005-11-06 to 2026-07-31.

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	7% 7% 2 6% 4 4 4 3 5% 7% 51%	147503
	Night	8% 9% 3 7% 5% 4 4 4 5% 6% 46%	142842
Transparency	Day	33% 6% 11% 23% 18% 8%	142288
	Night	37% 8% 13% 23% 15% 5%	139056
Seeing	Day	11% 12% 23% 27% 20% 8%	16774
	Night	12% 6% 20% 38% 21% 2	25767

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	13% 18% 6% 12% 7% 7% 6% 5% 6% 6% 15%	4722
	11th to 20th	Day	11% 9% 3 6% 4 4 4 3 5% 7% 45%	4740
	21st to end	Day	7% 10% 3 7% 6% 6% 6% 4 7% 8% 35%	5503
February	1st to 10th	Day	10% 15% 4 8% 5% 5% 6% 5% 6% 8% 29%	1890
	11th to 20th	Day	10% 14% 4 10% 6% 5% 5% 5% 5% 7% 31%	1852
	21st to end	Day	9% 15% 4 9% 5% 5% 6% 5% 6% 8% 28%	1730
March	1st to 10th	Day	7% 11% 4 8% 6% 5% 6% 4 7% 9% 32%	4634
	11th to 20th	Day	7% 13% 4 10% 6% 5% 5% 3 5% 6% 35%	5110
	21st to end	Day	8% 11% 4 11% 7% 7% 6% 5% 7% 9% 25%	5873
April	1st to 10th	Day	11% 13% 3 8% 6% 5% 6% 5% 6% 7% 31%	2520
	11th to 20th	Day	8% 11% 4 8% 6% 5% 5% 3 5% 7% 38%	2489
	21st to end	Day	7% 9% 2 6% 5% 4 5% 3 6% 8% 44%	2608
May	1st to 10th	Day	8% 5% 2 5% 4 3 4 3 5% 6% 55%	8195
	11th to 20th	Day	6% 5% 2 6% 4 5% 4 3 4 7% 53%	8160
	21st to end	Day	7% 5% 2 5% 3 4 4 4 5% 8% 52%	8992
June	1st to 10th	Day	10% 7% 3 6% 4 4 4 3 6% 6% 47%	2940
	11th to 20th	Day	8% 5% 2 6% 4 3 3 3 5% 7% 53%	2940
	21st to end	Day	4 3 1 4 3 2 3 4 5% 6% 65%	2940
July	1st to 10th	Day	2 1 1 2 1 2 2 2 3 4 81%	6459
	11th to 20th	Day	1 1 1 1 1 1 2 1 2 3 85%	6460
	21st to end	Day	2 1 1 2 1 2 2 2 3 4 80%	7021
August	1st to 10th	Day	2 3 1 3 2 2 3 3 5% 6% 71%	5999
	11th to 20th	Day	2 2 1 3 2 2 3 2 4 6% 74%	5758
	21st to end	Day	4 4 1 4 3 2 3 2 5% 6% 65%	5984
September	1st to 10th	Day	2 2 1 3 2 2 2 3 4 5% 75%	2400
	11th to 20th	Day	5% 4 2 5% 4 4 4 3 5% 7% 59%	2400
	21st to end	Day	9% 4 2 5% 3 2 3 3 4 6% 59%	2144
October	1st to 10th	Day	6% 5% 2 4 3 3 3 3 4 6% 62%	3280
	11th to 20th	Day	6% 6% 2 6% 5% 5% 5% 5% 6% 9% 46%	3261
	21st to end	Day	9% 9% 3 9% 5% 6% 5% 4 6% 7% 37%	3369
November	1st to 10th	Day	11% 13% 3 9% 5% 4 5% 4 6% 8% 31%	1854
	11th to 20th	Day	14% 10% 3 10% 7% 6% 6% 5% 7% 8% 25%	1696
	21st to end	Day	12% 11% 4 8% 6% 4 6% 4 6% 8% 32%	1680
December	1st to 10th	Day	9% 8% 3 5% 4 5% 4 5% 6% 7% 44%	2700
	11th to 20th	Day	12% 14% 4 11% 6% 7% 7% 6% 8% 7% 18%	3108
	21st to end	Day	11% 16% 5% 12% 7% 7% 6% 5% 6% 7% 19%	4092
January	1st to 10th	Night	12% 16% 5% 14% 8% 7% 6% 5% 5% 6% 15%	8172
	11th to 20th	Night	10% 10% 3 7% 4 4 4 3 5% 6% 46%	8220
	21st to end	Night	7% 11% 4 10% 6% 5% 5% 4 5% 7% 36%	8681
February	1st to 10th	Night	9% 14% 3 9% 6% 5% 6% 5% 6% 7% 29%	2730
	11th to 20th	Night	10% 13% 4 9% 5% 5% 5% 4 6% 7% 34%	2654
	21st to end	Night	9% 16% 4 8% 5% 5% 4 5% 6% 8% 29%	2076
March	1st to 10th	Night	7% 10% 3 8% 5% 6% 6% 5% 7% 9% 33%	5478
	11th to 20th	Night	6% 11% 4 8% 6% 5% 5% 4 5% 8% 39%	5110
	21st to end	Night	8% 12% 5% 11% 7% 7% 6% 5% 7% 9% 24%	5343
April	1st to 10th	Night	11% 13% 3 7% 4 5% 4 4 7% 7% 35%	2100
	11th to 20th	Night	8% 10% 3 8% 5% 5% 5% 4 5% 6% 40%	2079
	21st to end	Night	10% 9% 2 6% 4 4 5% 3 6% 7% 43%	2009
May	1st to 10th	Night	7% 6% 2 3 3 3 3 3 5% 7% 58%	4723
	11th to 20th	Night	7% 7% 2 6% 4 3 3 3 4 6% 54%	4700
	21st to end	Night	9% 7% 2 4 3 2 3 3 5% 7% 55%	5181
June	1st to 10th	Night	12% 7% 2 7% 3 4 3 3 5% 6% 48%	1680
	11th to 20th	Night	7% 5% 2 6% 3 3 3 3 4 7% 55%	1680
	21st to end	Night	5% 4 1 2 2 2 3 3 4 6% 68%	1680
July	1st to 10th	Night	1 1 1 2 2 2 3 2 3 4 79%	3720
	11th to 20th	Night	1 1 1 2 1 1 2 2 3 3 84%	3720
	21st to end	Night	2 1 1 2 1 2 2 2 4 5% 78%	4050
August	1st to 10th	Night	2 3 1 3 3 3 4 3 6% 8% 65%	3799
	11th to 20th	Night	1 1 1 3 3 3 3 3 4 6% 72%	4090
	21st to end	Night	3 3 1 4 3 3 3 2 5% 6% 67%	5015
September	1st to 10th	Night	2 1 1 3 2 2 2 3 4 4 76%	2000
	11th to 20th	Night	5% 3 2 4 3 3 4 3 5% 6% 62%	2000
	21st to end	Night	7% 4 2 4 2 3 4 2 5% 6% 61%	2253
October	1st to 10th	Night	6% 5% 2 4 3 2 2 2 3 4 68%	3920
	11th to 20th	Night	7% 6% 2 6% 4 4 4 4 6% 8% 49%	3897
	21st to end	Night	9% 7% 3 8% 5% 6% 5% 4 6% 8% 37%	4434
November	1st to 10th	Night	14% 11% 3 9% 6% 5% 5% 3 5% 7% 32%	2665
	11th to 20th	Night	14% 11% 4 9% 6% 6% 5% 4 6% 7% 28%	2921
	21st to end	Night	9% 11% 3 8% 6% 5% 6% 4 6% 8% 36%	2940
December	1st to 10th	Night	7% 8% 2 6% 4 4 4 4 6% 7% 49%	4700
	11th to 20th	Night	12% 16% 5% 12% 8% 7% 7% 6% 6% 6% 18%	5316
	21st to end	Night	12% 13% 4 11% 8% 6% 6% 4 6% 6% 24%	7106

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% 11% 12% 11% 2	4723
	11th to 20th	Day	37% 8% 10% 24% 17% 4	4740
	21st to end	Day	44% 9% 12% 20% 12% 3	5503
February	1st to 10th	Day	51% 9% 15% 18% 6% 1	1890
	11th to 20th	Day	49% 10% 15% 18% 7% 1	1861
	21st to end	Day	49% 10% 18% 15% 8% 1	1730
March	1st to 10th	Day	43% 9% 11% 23% 13% 1	4634
	11th to 20th	Day	47% 6% 11% 25% 11%	5110
	21st to end	Day	50% 11% 16% 18% 6%	5873
April	1st to 10th	Day	48% 9% 15% 20% 8% 1	2520
	11th to 20th	Day	44% 7% 14% 19% 13% 3	2492
	21st to end	Day	35% 9% 15% 27% 12% 2	2608
May	1st to 10th	Day	27% 5% 10% 29% 25% 3	8195
	11th to 20th	Day	29% 5% 13% 29% 23% 2	8163
	21st to end	Day	27% 7% 18% 30% 17% 1	8994
June	1st to 10th	Day	35% 7% 13% 27% 16% 3	2940
	11th to 20th	Day	29% 5% 13% 30% 19% 4	2940
	21st to end	Day	19% 5% 12% 31% 25% 9%	2940
July	1st to 10th	Day	9% 2 5% 18% 30% 36%	6391
	11th to 20th	Day	7% 2 4 9% 27% 50%	6385
	21st to end	Day	10% 2 5% 29% 34% 21%	6822
August	1st to 10th	Day	15% 2 5% 16% 39% 23%	4370
	11th to 20th	Day	14% 3 7% 32% 31% 13%	4169
	21st to end	Day	16% 3 7% 29% 30% 15%	4311
September	1st to 10th	Day	13% 4 8% 25% 32% 18%	2400
	11th to 20th	Day	24% 6% 11% 26% 24% 10%	2400
	21st to end	Day	26% 5% 13% 24% 23% 9%	2144
October	1st to 10th	Day	25% 5% 9% 26% 25% 11%	3280
	11th to 20th	Day	33% 7% 18% 25% 16% 2	3261
	21st to end	Day	44% 6% 10% 25% 13% 1	3369
November	1st to 10th	Day	49% 8% 14% 20% 8% 1	1854
	11th to 20th	Day	52% 11% 17% 14% 6%	1696
	21st to end	Day	46% 11% 17% 16% 9% 1	1680
December	1st to 10th	Day	38% 9% 13% 28% 11%	2700
	11th to 20th	Day	57% 10% 17% 13% 2	3108
	21st to end	Day	58% 11% 15% 14% 2	4092
January	1st to 10th	Night	63% 11% 14% 10% 2	8172
	11th to 20th	Night	37% 8% 9% 25% 17% 3	8220
	21st to end	Night	47% 9% 10% 18% 13% 3	8681
February	1st to 10th	Night	51% 11% 17% 15% 7%	2730
	11th to 20th	Night	46% 9% 17% 19% 7% 1	2656
	21st to end	Night	50% 11% 15% 16% 9% 1	2076
March	1st to 10th	Night	41% 9% 13% 25% 11% 2	5478
	11th to 20th	Night	40% 8% 16% 27% 9%	5110
	21st to end	Night	48% 16% 17% 15% 4	5343
April	1st to 10th	Night	44% 9% 19% 19% 8% 1	2100
	11th to 20th	Night	42% 9% 17% 20% 11% 2	2079
	21st to end	Night	39% 9% 15% 22% 11% 3	2009
May	1st to 10th	Night	23% 6% 12% 32% 26% 1	4721
	11th to 20th	Night	28% 5% 17% 34% 15% 1	4700
	21st to end	Night	26% 7% 25% 28% 13% 1	5182
June	1st to 10th	Night	35% 9% 13% 27% 14% 1	1680
	11th to 20th	Night	28% 6% 14% 34% 15% 4	1680
	21st to end	Night	19% 4 12% 33% 24% 7%	1680
July	1st to 10th	Night	11% 2 6% 23% 25% 32%	3680
	11th to 20th	Night	7% 2 5% 13% 25% 48%	3672
	21st to end	Night	9% 2 5% 34% 32% 19%	3937
August	1st to 10th	Night	14% 3 7% 18% 37% 22%	2756
	11th to 20th	Night	13% 3 10% 38% 27% 9%	2954
	21st to end	Night	13% 3 11% 31% 30% 13%	3608
September	1st to 10th	Night	12% 4 8% 29% 32% 16%	2000
	11th to 20th	Night	21% 6% 11% 26% 23% 11%	2000
	21st to end	Night	23% 5% 12% 26% 24% 10%	2253
October	1st to 10th	Night	22% 4 9% 28% 33% 4	3920
	11th to 20th	Night	31% 6% 21% 24% 17% 2	3897
	21st to end	Night	41% 7% 11% 27% 13% 1	4434
November	1st to 10th	Night	49% 9% 13% 19% 9% 1	2665
	11th to 20th	Night	52% 11% 15% 18% 4	2921
	21st to end	Night	43% 9% 17% 20% 10% 1	2940
December	1st to 10th	Night	34% 7% 14% 33% 12%	4700
	11th to 20th	Night	62% 9% 14% 11% 4	5316
	21st to end	Night	54% 12% 18% 12% 4	7106

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	25% 16% 24% 22% 11% 1	220
	11th to 20th	Day	17% 7% 23% 32% 15% 6%	220
	21st to end	Day	16% 12% 22% 26% 20% 4	352
February	1st to 10th	Day	19% 16% 22% 27% 14% 2	430
	11th to 20th	Day	17% 13% 28% 27% 13% 2	430
	21st to end	Day	20% 16% 26% 26% 11% 1	446
March	1st to 10th	Day	18% 16% 29% 26% 10% 2	540
	11th to 20th	Day	18% 18% 22% 26% 14% 3	540
	21st to end	Day	16% 20% 26% 26% 12% 1	594
April	1st to 10th	Day	21% 15% 22% 23% 14% 5%	540
	11th to 20th	Day	16% 17% 28% 22% 12% 5%	532
	21st to end	Day	11% 18% 25% 23% 17% 6%	540
May	1st to 10th	Day	11% 15% 26% 25% 17% 6%	543
	11th to 20th	Day	15% 14% 25% 24% 16% 7%	568
	21st to end	Day	13% 9% 21% 28% 20% 9%	617
June	1st to 10th	Day	9% 14% 24% 24% 21% 9%	570
	11th to 20th	Day	8% 16% 25% 29% 17% 5%	570
	21st to end	Day	5% 8% 23% 30% 25% 9%	570
July	1st to 10th	Day	2 6% 23% 32% 25% 11%	566
	11th to 20th	Day	2 8% 24% 27% 27% 12%	564
	21st to end	Day	1 5% 23% 28% 27% 15%	616
August	1st to 10th	Day	2 4 21% 32% 25% 15%	527
	11th to 20th	Day	2 5% 18% 28% 29% 18%	517
	21st to end	Day	4 7% 20% 28% 27% 13%	583
September	1st to 10th	Day	3 5% 22% 26% 28% 16%	530
	11th to 20th	Day	6% 7% 20% 28% 28% 11%	530
	21st to end	Day	11% 8% 18% 27% 27% 9%	530
October	1st to 10th	Day	9% 9% 21% 29% 22% 9%	530
	11th to 20th	Day	12% 11% 22% 24% 25% 7%	530
	21st to end	Day	14% 15% 23% 22% 21% 5%	469
November	1st to 10th	Day	16% 11% 25% 31% 15% 2	330
	11th to 20th	Day	15% 12% 25% 26% 18% 4	228
	21st to end	Day	20% 10% 20% 30% 18% 3	220
December	1st to 10th	Day	15% 10% 24% 26% 16% 9%	220
	11th to 20th	Day	21% 11% 29% 29% 9% 1	220
	21st to end	Day	16% 13% 29% 29% 12% 2	242
January	1st to 10th	Night	18% 10% 28% 30% 13% 2	840
	11th to 20th	Night	15% 9% 22% 30% 21% 2	840
	21st to end	Night	15% 8% 18% 38% 19% 2	924
February	1st to 10th	Night	15% 8% 27% 33% 15% 2	840
	11th to 20th	Night	15% 8% 25% 34% 17% 1	824
	21st to end	Night	18% 11% 26% 34% 11%	692
March	1st to 10th	Night	16% 10% 27% 35% 12% 1	840
	11th to 20th	Night	12% 10% 25% 37% 15% 2	840
	21st to end	Night	11% 11% 29% 35% 15% 1	924
April	1st to 10th	Night	16% 7% 21% 34% 20% 1	840
	11th to 20th	Night	12% 9% 26% 36% 16% 2	831
	21st to end	Night	13% 8% 22% 37% 18% 1	749
May	1st to 10th	Night	10% 5% 23% 40% 21% 1	420
	11th to 20th	Night	12% 4 18% 41% 24% 1	414
	21st to end	Night	8% 5% 15% 44% 26% 1	455
June	1st to 10th	Night	13% 4 17% 46% 19% 1	420
	11th to 20th	Night	7% 4 23% 46% 20%	420
	21st to end	Night	8% 1 13% 50% 27% 1	420
July	1st to 10th	Night	3 9% 60% 28% 1	410
	11th to 20th	Night	1 1 17% 57% 23% 1	408
	21st to end	Night	1 1 9% 53% 34% 2	458
August	1st to 10th	Night	1 1 6% 53% 35% 4	488
	11th to 20th	Night	1 1 5% 39% 46% 7%	606
	21st to end	Night	2 3 15% 46% 32% 2	880
September	1st to 10th	Night	2 2 16% 42% 35% 4	800
	11th to 20th	Night	5% 2 12% 41% 34% 6%	800
	21st to end	Night	9% 3 13% 39% 32% 5%	800
October	1st to 10th	Night	11% 3 17% 40% 26% 3	800
	11th to 20th	Night	12% 5% 18% 37% 26% 4	800
	21st to end	Night	13% 6% 21% 38% 18% 4	880
November	1st to 10th	Night	16% 8% 23% 36% 17%	820
	11th to 20th	Night	19% 9% 24% 32% 16% 1	840
	21st to end	Night	14% 8% 22% 35% 19% 2	840
December	1st to 10th	Night	16% 7% 21% 33% 19% 3	840
	11th to 20th	Night	19% 7% 24% 34% 15% 1	840
	21st to end	Night	20% 11% 29% 29% 11% 1	924

Page generated at 2026-07-28 00:25:21. Version ac07

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