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 2024-02-20.

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	9% 8% 3 6% 5% 3 5% 5% 5% 7% 45%	78326
	Night	9% 9% 3 7% 6% 3 5% 5% 5% 6% 40%	80886
Transparency	Day	37% 8% 13% 20% 15% 6%	78029
	Night	41% 9% 14% 18% 13% 4	80704
Seeing	Day	12% 12% 24% 27% 19% 7%	13593
	Night	12% 6% 20% 37% 22% 2	22813

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	14% 16% 5% 9% 8% 5% 7% 6% 6% 7% 17%	2539
	11th to 20th	Day	21% 16% 4 9% 8% 5% 5% 4 6% 6% 17%	2540
	21st to end	Day	12% 13% 5% 7% 7% 5% 6% 6% 6% 9% 24%	2958
February	1st to 10th	Day	11% 14% 4 6% 6% 4 7% 6% 5% 8% 29%	1710
	11th to 20th	Day	10% 12% 5% 8% 7% 4 5% 6% 5% 7% 32%	1662
	21st to end	Day	8% 14% 4 9% 6% 4 7% 7% 6% 8% 27%	1480
March	1st to 10th	Day	9% 13% 6% 8% 7% 3 6% 6% 8% 8% 27%	1803
	11th to 20th	Day	10% 12% 5% 9% 8% 5% 5% 5% 6% 7% 28%	1980
	21st to end	Day	11% 12% 4 10% 9% 4 7% 7% 5% 7% 25%	2283
April	1st to 10th	Day	12% 12% 4 7% 6% 4 6% 6% 6% 7% 30%	2160
	11th to 20th	Day	9% 11% 4 8% 6% 4 5% 4 5% 7% 37%	2129
	21st to end	Day	8% 9% 3 5% 5% 3 6% 4 6% 9% 43%	2235
May	1st to 10th	Day	8% 7% 3 6% 5% 3 4 5% 6% 8% 47%	2520
	11th to 20th	Day	10% 7% 3 5% 6% 4 5% 5% 5% 9% 42%	2477
	21st to end	Day	12% 7% 4 6% 5% 3 4 4 6% 8% 41%	2723
June	1st to 10th	Day	12% 7% 3 5% 4 3 4 4 5% 7% 44%	2520
	11th to 20th	Day	9% 5% 3 5% 4 3 4 4 5% 7% 51%	2520
	21st to end	Day	4 3 1 3 3 1 3 4 4 6% 67%	2520
July	1st to 10th	Day	2 1 1 2 2 1 3 3 3 5% 75%	2520
	11th to 20th	Day	2 1 1 2 2 2 3 2 3 5% 76%	2520
	21st to end	Day	2 1 1 2 1 1 2 2 3 4 82%	2741
August	1st to 10th	Day	2 1 1 2 3 2 3 3 4 5% 74%	2423
	11th to 20th	Day	3 1 2 2 1 2 3 4 5% 76%	2286
	21st to end	Day	3 2 1 2 2 1 2 3 3 5% 77%	2376
September	1st to 10th	Day	2 2 1 2 2 1 2 3 3 5% 77%	2160
	11th to 20th	Day	5% 4 2 4 5% 3 4 4 4 7% 59%	2160
	21st to end	Day	9% 4 2 5% 3 2 3 4 4 6% 57%	1932
October	1st to 10th	Day	9% 7% 3 5% 5% 2 4 5% 4 6% 50%	1800
	11th to 20th	Day	9% 6% 3 6% 5% 3 4 5% 5% 8% 46%	1800
	21st to end	Day	11% 6% 3 7% 5% 4 5% 5% 6% 6% 42%	1878
November	1st to 10th	Day	12% 11% 4 8% 6% 3 6% 6% 6% 8% 31%	1674
	11th to 20th	Day	15% 9% 4 8% 8% 4 6% 6% 7% 8% 25%	1535
	21st to end	Day	12% 9% 5% 7% 6% 4 5% 6% 7% 7% 33%	1520
December	1st to 10th	Day	11% 9% 4 6% 6% 4 7% 6% 6% 6% 34%	1520
	11th to 20th	Day	11% 13% 4 8% 7% 5% 7% 9% 8% 8% 21%	1928
	21st to end	Day	11% 15% 6% 9% 8% 5% 6% 6% 6% 6% 22%	2794
January	1st to 10th	Night	11% 17% 6% 11% 10% 6% 7% 6% 5% 6% 16%	4406
	11th to 20th	Night	18% 17% 5% 10% 9% 4 5% 5% 6% 5% 16%	4420
	21st to end	Night	11% 13% 5% 11% 9% 4 6% 6% 6% 7% 23%	4702
February	1st to 10th	Night	9% 13% 4 8% 7% 4 6% 6% 6% 8% 29%	2470
	11th to 20th	Night	10% 12% 4 8% 5% 3 5% 4 6% 6% 35%	2388
	21st to end	Night	10% 15% 5% 7% 6% 4 5% 5% 6% 8% 29%	1776
March	1st to 10th	Night	12% 13% 4 6% 6% 4 5% 6% 6% 7% 29%	2155
	11th to 20th	Night	8% 11% 5% 7% 8% 4 5% 5% 6% 10% 31%	1980
	21st to end	Night	6% 12% 5% 8% 7% 4 8% 7% 8% 7% 28%	2072
April	1st to 10th	Night	12% 12% 4 7% 5% 4 5% 5% 6% 7% 34%	1800
	11th to 20th	Night	9% 9% 4 8% 6% 3 5% 5% 5% 6% 39%	1779
	21st to end	Night	12% 9% 3 5% 5% 3 5% 4 6% 8% 40%	1723
May	1st to 10th	Night	9% 7% 2 4 5% 3 5% 4 6% 7% 48%	1440
	11th to 20th	Night	10% 6% 3 5% 5% 3 3 5% 6% 7% 46%	1416
	21st to end	Night	10% 7% 3 5% 6% 3 4 5% 5% 7% 44%	1552
June	1st to 10th	Night	13% 6% 3 6% 4 3 4 4 5% 6% 46%	1440
	11th to 20th	Night	9% 6% 2 5% 4 2 4 4 4 7% 54%	1440
	21st to end	Night	5% 3 1 2 3 2 3 3 3 5% 68%	1440
July	1st to 10th	Night	2 1 1 2 3 1 3 3 4 5% 76%	1440
	11th to 20th	Night	1 1 1 2 1 1 2 3 3 5% 79%	1440
	21st to end	Night	1 1 1 1 1 1 2 2 3 4 83%	1576
August	1st to 10th	Night	1 1 1 2 2 1 2 3 4 6% 75%	1512
	11th to 20th	Night	2 1 1 2 3 2 2 3 3 5% 77%	1612
	21st to end	Night	1 2 1 2 2 1 3 3 3 5% 76%	1980
September	1st to 10th	Night	2 1 1 2 2 1 2 3 4 4 79%	1800
	11th to 20th	Night	5% 3 2 3 3 2 4 4 5% 5% 63%	1800
	21st to end	Night	8% 5% 2 4 3 2 3 4 4 6% 59%	2026
October	1st to 10th	Night	9% 7% 3 5% 4 2 3 3 4 5% 56%	2160
	11th to 20th	Night	9% 6% 2 5% 5% 3 3 4 6% 6% 51%	2160
	21st to end	Night	12% 8% 3 6% 5% 4 4 4 5% 6% 44%	2476
November	1st to 10th	Night	15% 10% 3 8% 7% 3 5% 4 5% 7% 32%	2405
	11th to 20th	Night	15% 9% 4 8% 7% 5% 5% 5% 6% 7% 29%	2642
	21st to end	Night	9% 10% 3 6% 6% 4 5% 6% 6% 7% 37%	2660
December	1st to 10th	Night	11% 12% 4 8% 6% 4 5% 5% 7% 6% 32%	2660
	11th to 20th	Night	11% 14% 5% 10% 9% 5% 6% 7% 6% 6% 22%	3276
	21st to end	Night	11% 12% 5% 10% 9% 5% 6% 5% 5% 6% 26%	4862

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	58% 14% 14% 12% 2	2539
	11th to 20th	Day	63% 13% 12% 7% 3 2	2540
	21st to end	Day	54% 14% 17% 10% 4 1	2958
February	1st to 10th	Day	51% 10% 16% 17% 5% 1	1710
	11th to 20th	Day	48% 11% 16% 18% 7% 1	1671
	21st to end	Day	50% 11% 18% 15% 6% 1	1480
March	1st to 10th	Day	50% 10% 16% 16% 7% 1	1803
	11th to 20th	Day	53% 7% 14% 22% 5%	1980
	21st to end	Day	54% 11% 15% 16% 5%	2283
April	1st to 10th	Day	50% 9% 14% 17% 9% 1	2160
	11th to 20th	Day	46% 7% 15% 17% 11% 3	2132
	21st to end	Day	36% 9% 15% 26% 11% 2	2235
May	1st to 10th	Day	33% 7% 16% 27% 16% 1	2520
	11th to 20th	Day	38% 8% 14% 25% 14% 2	2480
	21st to end	Day	41% 8% 15% 24% 12% 1	2724
June	1st to 10th	Day	38% 7% 13% 27% 13% 2	2520
	11th to 20th	Day	31% 6% 14% 31% 15% 3	2520
	21st to end	Day	18% 5% 12% 31% 25% 9%	2520
July	1st to 10th	Day	13% 4 9% 21% 30% 22%	2451
	11th to 20th	Day	12% 3 8% 14% 33% 30%	2445
	21st to end	Day	9% 2 4 15% 40% 30%	2589
August	1st to 10th	Day	12% 4 8% 25% 34% 17%	2406
	11th to 20th	Day	12% 3 7% 24% 35% 20%	2286
	21st to end	Day	12% 3 7% 29% 36% 14%	2376
September	1st to 10th	Day	11% 4 8% 26% 32% 19%	2160
	11th to 20th	Day	24% 6% 11% 24% 24% 11%	2160
	21st to end	Day	28% 5% 14% 23% 21% 9%	1932
October	1st to 10th	Day	34% 7% 10% 22% 20% 6%	1800
	11th to 20th	Day	35% 8% 15% 22% 16% 3	1800
	21st to end	Day	42% 8% 14% 21% 13% 2	1878
November	1st to 10th	Day	48% 9% 14% 20% 8% 1	1674
	11th to 20th	Day	52% 12% 16% 14% 6%	1535
	21st to end	Day	46% 11% 17% 15% 10% 1	1520
December	1st to 10th	Day	46% 13% 15% 19% 6%	1520
	11th to 20th	Day	52% 13% 20% 14% 2	1928
	21st to end	Day	55% 13% 16% 15% 2	2794
January	1st to 10th	Night	59% 17% 15% 8% 2	4406
	11th to 20th	Night	62% 13% 12% 7% 4 1	4420
	21st to end	Night	58% 14% 13% 11% 4	4702
February	1st to 10th	Night	51% 11% 17% 14% 7%	2470
	11th to 20th	Night	45% 10% 18% 19% 7% 1	2390
	21st to end	Night	51% 11% 15% 16% 7% 1	1776
March	1st to 10th	Night	49% 10% 15% 18% 7% 1	2155
	11th to 20th	Night	46% 9% 20% 21% 4	1980
	21st to end	Night	48% 14% 17% 16% 5%	2072
April	1st to 10th	Night	46% 9% 19% 18% 8% 1	1800
	11th to 20th	Night	44% 9% 16% 18% 11% 2	1779
	21st to end	Night	41% 10% 15% 21% 10% 3	1723
May	1st to 10th	Night	32% 7% 18% 29% 14% 1	1440
	11th to 20th	Night	36% 8% 17% 27% 12% 2	1416
	21st to end	Night	37% 9% 19% 24% 11%	1552
June	1st to 10th	Night	37% 10% 15% 27% 11% 1	1440
	11th to 20th	Night	28% 7% 17% 34% 12% 3	1440
	21st to end	Night	19% 5% 12% 33% 24% 7%	1440
July	1st to 10th	Night	12% 4 12% 25% 29% 19%	1400
	11th to 20th	Night	9% 4 9% 20% 29% 30%	1392
	21st to end	Night	7% 2 5% 18% 41% 27%	1488
August	1st to 10th	Night	10% 4 10% 26% 35% 15%	1504
	11th to 20th	Night	12% 3 9% 24% 37% 15%	1612
	21st to end	Night	12% 3 8% 27% 39% 11%	1980
September	1st to 10th	Night	9% 3 9% 29% 33% 17%	1800
	11th to 20th	Night	21% 7% 11% 25% 24% 13%	1800
	21st to end	Night	25% 5% 12% 25% 23% 11%	2026
October	1st to 10th	Night	32% 5% 10% 25% 23% 5%	2160
	11th to 20th	Night	31% 8% 15% 23% 19% 4	2160
	21st to end	Night	38% 9% 14% 19% 18% 2	2476
November	1st to 10th	Night	49% 10% 13% 19% 9% 1	2405
	11th to 20th	Night	51% 11% 15% 19% 4	2642
	21st to end	Night	43% 10% 17% 19% 11% 1	2660
December	1st to 10th	Night	50% 10% 18% 17% 5%	2660
	11th to 20th	Night	58% 10% 16% 11% 4	3276
	21st to end	Night	53% 14% 18% 12% 3	4862

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	26% 15% 22% 22% 13% 2	180
	11th to 20th	Day	21% 8% 26% 30% 10% 5%	180
	21st to end	Day	18% 11% 24% 25% 19% 4	297
February	1st to 10th	Day	19% 15% 22% 28% 13% 2	370
	11th to 20th	Day	17% 14% 30% 25% 12% 2	366
	21st to end	Day	20% 15% 28% 25% 11% 1	346
March	1st to 10th	Day	20% 16% 27% 25% 10% 2	420
	11th to 20th	Day	17% 17% 22% 27% 15% 3	420
	21st to end	Day	18% 20% 24% 26% 12%	462
April	1st to 10th	Day	24% 16% 22% 22% 11% 5%	420
	11th to 20th	Day	18% 20% 27% 19% 10% 6%	412
	21st to end	Day	12% 21% 25% 23% 15% 5%	420
May	1st to 10th	Day	12% 17% 26% 25% 16% 5%	423
	11th to 20th	Day	17% 12% 25% 23% 15% 8%	448
	21st to end	Day	15% 10% 21% 28% 18% 8%	485
June	1st to 10th	Day	9% 14% 25% 23% 20% 9%	450
	11th to 20th	Day	9% 17% 27% 29% 14% 4	450
	21st to end	Day	4 9% 23% 32% 24% 8%	450
July	1st to 10th	Day	2 7% 26% 33% 25% 7%	446
	11th to 20th	Day	2 9% 26% 26% 27% 11%	444
	21st to end	Day	1 5% 25% 28% 28% 13%	487
August	1st to 10th	Day	2 5% 21% 34% 23% 15%	447
	11th to 20th	Day	2 5% 19% 28% 28% 18%	437
	21st to end	Day	4 7% 21% 29% 26% 12%	495
September	1st to 10th	Day	2 6% 24% 25% 28% 14%	450
	11th to 20th	Day	6% 8% 21% 28% 28% 10%	450
	21st to end	Day	12% 9% 19% 27% 26% 6%	450
October	1st to 10th	Day	9% 10% 23% 28% 22% 8%	450
	11th to 20th	Day	13% 11% 21% 22% 26% 8%	450
	21st to end	Day	14% 14% 24% 22% 21% 5%	393
November	1st to 10th	Day	16% 10% 24% 32% 15% 2	270
	11th to 20th	Day	15% 10% 25% 27% 18% 5%	187
	21st to end	Day	22% 9% 20% 28% 18% 3	180
December	1st to 10th	Day	14% 10% 25% 28% 14% 9%	180
	11th to 20th	Day	21% 11% 29% 31% 7% 2	180
	21st to end	Day	17% 12% 28% 28% 13% 3	198
January	1st to 10th	Night	18% 9% 28% 29% 14% 3	760
	11th to 20th	Night	16% 10% 22% 29% 20% 2	760
	21st to end	Night	16% 8% 17% 38% 19% 1	836
February	1st to 10th	Night	15% 8% 27% 34% 15% 2	760
	11th to 20th	Night	15% 8% 25% 34% 18% 1	742
	21st to end	Night	17% 11% 26% 35% 11% 1	592
March	1st to 10th	Night	17% 9% 26% 35% 13% 1	720
	11th to 20th	Night	11% 9% 23% 38% 17% 1	720
	21st to end	Night	10% 11% 28% 35% 16% 1	792
April	1st to 10th	Night	17% 8% 22% 33% 19% 1	720
	11th to 20th	Night	12% 9% 26% 34% 17% 2	711
	21st to end	Night	15% 8% 22% 35% 18% 1	643
May	1st to 10th	Night	11% 5% 23% 39% 21% 1	360
	11th to 20th	Night	12% 4 16% 41% 26% 1	354
	21st to end	Night	8% 5% 16% 44% 25% 2	389
June	1st to 10th	Night	13% 4 17% 45% 20% 1	360
	11th to 20th	Night	8% 4 24% 44% 19% 1	360
	21st to end	Night	7% 1 15% 50% 27% 1	360
July	1st to 10th	Night	3 9% 60% 27% 1	350
	11th to 20th	Night	1 17% 57% 24% 1	348
	21st to end	Night	1 10% 52% 35% 2	394
August	1st to 10th	Night	1 1 6% 50% 37% 5%	438
	11th to 20th	Night	2 1 5% 36% 49% 7%	544
	21st to end	Night	2 3 16% 44% 32% 2	792
September	1st to 10th	Night	2 2 17% 43% 34% 3	720
	11th to 20th	Night	5% 2 12% 39% 35% 7%	720
	21st to end	Night	10% 3 12% 38% 32% 5%	720
October	1st to 10th	Night	12% 3 18% 38% 26% 4	720
	11th to 20th	Night	12% 4 17% 36% 26% 4	720
	21st to end	Night	13% 6% 20% 37% 18% 5%	792
November	1st to 10th	Night	15% 8% 22% 37% 17% 1	740
	11th to 20th	Night	18% 9% 24% 31% 17% 1	760
	21st to end	Night	14% 7% 23% 35% 19% 3	760
December	1st to 10th	Night	17% 6% 21% 34% 19% 2	760
	11th to 20th	Night	18% 6% 25% 34% 15% 1	760
	21st to end	Night	19% 11% 29% 29% 11% 1	836

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