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 2024-10-20.

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	7% 8% 3 6% 4 4 4 3 5% 6% 50%	101417
	Night	8% 9% 3 7% 5% 4 4 4 5% 6% 44%	97434
Transparency	Day	33% 7% 12% 21% 17% 10%	101160
	Night	37% 9% 14% 20% 13% 6%	97280
Seeing	Day	12% 12% 24% 27% 19% 7%	14564
	Night	12% 6% 20% 38% 22% 2	23572

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% 17% 5% 11% 7% 7% 6% 5% 6% 7% 17%	2539
	11th to 20th	Day	20% 16% 4 11% 6% 6% 4 3 6% 6% 17%	2540
	21st to end	Day	12% 14% 4 8% 6% 6% 6% 4 7% 8% 24%	2958
February	1st to 10th	Day	11% 14% 3 7% 5% 5% 6% 5% 6% 8% 29%	1710
	11th to 20th	Day	10% 14% 4 10% 5% 5% 5% 5% 5% 7% 32%	1670
	21st to end	Day	8% 15% 4 10% 6% 6% 6% 5% 6% 8% 27%	1570
March	1st to 10th	Day	6% 12% 5% 9% 6% 6% 6% 4 7% 9% 31%	3154
	11th to 20th	Day	6% 9% 3 7% 5% 4 4 3 5% 6% 47%	3490
	21st to end	Day	8% 12% 4 11% 7% 7% 6% 5% 6% 8% 26%	4007
April	1st to 10th	Day	11% 13% 3 8% 6% 5% 5% 5% 6% 7% 31%	2280
	11th to 20th	Day	9% 12% 4 8% 6% 5% 5% 3 5% 6% 37%	2249
	21st to end	Day	7% 10% 3 6% 5% 4 5% 3 6% 8% 42%	2360
May	1st to 10th	Day	12% 8% 3 6% 4 3 4 3 5% 6% 46%	4420
	11th to 20th	Day	5% 4 2 4 3 3 3 3 4 6% 64%	4377
	21st to end	Day	10% 7% 3 6% 4 4 4 4 6% 7% 45%	4813
June	1st to 10th	Day	11% 8% 3 6% 4 4 4 3 6% 7% 44%	2660
	11th to 20th	Day	8% 6% 3 6% 4 4 3 3 5% 7% 51%	2660
	21st to end	Day	4 3 1 3 3 2 3 3 4 6% 67%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 2 3 85%	4420
	11th to 20th	Day	1 1 1 2 2 1 2 2 2 4 82%	4420
	21st to end	Day	2 1 1 2 1 2 2 2 3 4 81%	4790
August	1st to 10th	Day	3 3 1 3 2 2 2 2 4 5% 73%	4251
	11th to 20th	Day	2 2 1 3 2 2 3 2 4 6% 72%	4001
	21st to end	Day	3 3 1 3 2 2 3 2 4 5% 72%	4180
September	1st to 10th	Day	2 2 1 2 2 2 2 3 4 5% 76%	2280
	11th to 20th	Day	5% 4 2 5% 4 4 4 3 5% 7% 58%	2280
	21st to end	Day	9% 4 2 5% 3 3 3 3 4 6% 58%	2038
October	1st to 10th	Day	9% 7% 3 5% 4 3 4 3 4 6% 52%	1900
	11th to 20th	Day	8% 6% 2 7% 5% 4 4 4 6% 8% 46%	1891
	21st to end	Day	11% 7% 3 8% 5% 5% 5% 3 6% 6% 41%	1878
November	1st to 10th	Day	12% 13% 3 9% 5% 4 5% 5% 6% 8% 31%	1674
	11th to 20th	Day	14% 10% 3 10% 7% 6% 5% 5% 7% 7% 25%	1535
	21st to end	Day	12% 11% 4 8% 6% 4 6% 4 7% 7% 32%	1520
December	1st to 10th	Day	11% 10% 4 8% 6% 6% 5% 5% 6% 6% 34%	1520
	11th to 20th	Day	11% 13% 3 10% 6% 6% 7% 7% 9% 7% 21%	1928
	21st to end	Day	10% 16% 5% 10% 7% 6% 6% 5% 6% 6% 22%	2794
January	1st to 10th	Night	11% 17% 5% 12% 8% 7% 7% 5% 5% 6% 16%	4406
	11th to 20th	Night	18% 18% 5% 12% 7% 6% 5% 4 6% 5% 16%	4420
	21st to end	Night	10% 14% 5% 12% 7% 5% 6% 4 6% 7% 23%	4702
February	1st to 10th	Night	9% 14% 3 9% 6% 6% 6% 5% 6% 7% 29%	2470
	11th to 20th	Night	10% 13% 4 9% 5% 5% 5% 4 6% 6% 35%	2396
	21st to end	Night	10% 17% 4 8% 6% 6% 4 5% 6% 8% 28%	1884
March	1st to 10th	Night	7% 12% 4 8% 5% 6% 6% 5% 6% 8% 33%	3718
	11th to 20th	Night	5% 9% 3 6% 5% 3 4 3 5% 7% 51%	3490
	21st to end	Night	7% 12% 4 11% 7% 7% 7% 6% 7% 8% 24%	3645
April	1st to 10th	Night	11% 13% 4 7% 4 5% 5% 4 6% 6% 35%	1900
	11th to 20th	Night	9% 10% 3 8% 5% 5% 5% 4 5% 7% 40%	1879
	21st to end	Night	11% 10% 2 6% 5% 4 5% 4 6% 8% 40%	1818
May	1st to 10th	Night	13% 10% 3 5% 4 4 4 3 5% 6% 45%	2540
	11th to 20th	Night	6% 5% 2 4 3 3 2 2 4 5% 63%	2516
	21st to end	Night	11% 8% 3 6% 3 3 4 3 4 6% 50%	2762
June	1st to 10th	Night	13% 7% 2 7% 3 4 3 3 4 6% 46%	1520
	11th to 20th	Night	8% 6% 2 6% 3 3 3 3 4 7% 54%	1520
	21st to end	Night	5% 4 1 3 3 2 3 3 3 5% 69%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 2 3 86%	2540
	11th to 20th	Night	1 1 1 2 1 2 2 2 3 4 81%	2540
	21st to end	Night	1 1 1 1 1 1 2 2 3 3 84%	2761
August	1st to 10th	Night	1 2 1 3 2 2 3 3 5% 6% 72%	2679
	11th to 20th	Night	1 1 1 3 2 3 3 3 4 6% 74%	2836
	21st to end	Night	2 2 1 3 2 2 3 2 4 6% 74%	3498
September	1st to 10th	Night	2 1 1 2 1 2 2 2 4 4 79%	1900
	11th to 20th	Night	5% 3 2 4 3 3 4 3 5% 6% 62%	1900
	21st to end	Night	7% 4 2 4 2 3 4 2 4 6% 60%	2140
October	1st to 10th	Night	8% 7% 2 6% 3 2 2 2 3 5% 57%	2280
	11th to 20th	Night	9% 7% 2 6% 4 3 3 4 6% 6% 50%	2273
	21st to end	Night	12% 8% 3 7% 4 5% 4 3 5% 6% 44%	2476
November	1st to 10th	Night	14% 11% 3 9% 6% 5% 5% 3 5% 7% 32%	2405
	11th to 20th	Night	14% 10% 4 9% 6% 6% 5% 4 6% 7% 29%	2642
	21st to end	Night	9% 11% 3 7% 5% 5% 5% 4 6% 7% 36%	2660
December	1st to 10th	Night	11% 13% 3 8% 5% 6% 5% 4 7% 6% 31%	2660
	11th to 20th	Night	11% 15% 5% 11% 7% 7% 6% 5% 6% 6% 21%	3276
	21st to end	Night	11% 13% 4 11% 8% 6% 6% 4 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% 10% 16% 18% 7% 1	1679
	21st to end	Day	49% 11% 19% 15% 6% 1	1570
March	1st to 10th	Day	42% 11% 14% 22% 11%	3154
	11th to 20th	Day	36% 7% 13% 32% 12%	3490
	21st to end	Day	49% 13% 16% 17% 5%	4007
April	1st to 10th	Day	49% 10% 15% 17% 9% 1	2280
	11th to 20th	Day	45% 8% 14% 18% 12% 3	2252
	21st to end	Day	36% 9% 15% 27% 11% 2	2360
May	1st to 10th	Day	35% 7% 15% 26% 17% 1	4420
	11th to 20th	Day	22% 5% 10% 29% 31% 3	4380
	21st to end	Day	34% 10% 20% 26% 10% 1	4814
June	1st to 10th	Day	38% 7% 13% 26% 13% 2	2660
	11th to 20th	Day	30% 6% 14% 31% 16% 3	2660
	21st to end	Day	18% 5% 12% 31% 26% 9%	2660
July	1st to 10th	Day	7% 2 5% 12% 24% 49%	4351
	11th to 20th	Day	8% 2 5% 9% 23% 54%	4345
	21st to end	Day	9% 2 5% 18% 36% 30%	4639
August	1st to 10th	Day	15% 2 5% 15% 40% 23%	4235
	11th to 20th	Day	14% 3 7% 32% 31% 12%	4040
	21st to end	Day	16% 3 7% 29% 30% 15%	4179
September	1st to 10th	Day	11% 4 7% 25% 33% 19%	2280
	11th to 20th	Day	24% 6% 12% 25% 23% 10%	2280
	21st to end	Day	27% 5% 14% 24% 22% 8%	2038
October	1st to 10th	Day	33% 7% 10% 23% 20% 7%	1900
	11th to 20th	Day	35% 8% 16% 22% 16% 3	1891
	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	2398
	21st to end	Night	50% 11% 15% 15% 7% 1	1884
March	1st to 10th	Night	42% 11% 15% 23% 8% 1	3718
	11th to 20th	Night	30% 8% 18% 34% 10%	3490
	21st to end	Night	46% 18% 18% 14% 4	3645
April	1st to 10th	Night	45% 10% 20% 17% 8% 1	1900
	11th to 20th	Night	42% 9% 17% 19% 10% 2	1879
	21st to end	Night	41% 10% 15% 21% 10% 3	1818
May	1st to 10th	Night	34% 10% 16% 28% 12%	2540
	11th to 20th	Night	22% 5% 13% 39% 20% 1	2516
	21st to end	Night	30% 10% 32% 22% 6%	2762
June	1st to 10th	Night	37% 10% 14% 26% 12% 1	1520
	11th to 20th	Night	28% 7% 16% 34% 12% 3	1520
	21st to end	Night	19% 4 12% 33% 25% 7%	1520
July	1st to 10th	Night	7% 2 7% 14% 26% 44%	2500
	11th to 20th	Night	9% 2 5% 14% 19% 50%	2492
	21st to end	Night	7% 2 5% 21% 38% 28%	2674
August	1st to 10th	Night	13% 3 6% 17% 38% 23%	2671
	11th to 20th	Night	13% 3 9% 38% 28% 9%	2863
	21st to end	Night	12% 3 11% 31% 30% 12%	3498
September	1st to 10th	Night	10% 3 8% 29% 33% 17%	1900
	11th to 20th	Night	22% 6% 11% 26% 23% 12%	1900
	21st to end	Night	24% 5% 12% 26% 23% 10%	2140
October	1st to 10th	Night	31% 5% 10% 26% 24% 4	2280
	11th to 20th	Night	31% 8% 16% 22% 19% 3	2273
	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% 29% 26% 12% 2	368
	21st to end	Day	19% 15% 28% 25% 11% 1	382
March	1st to 10th	Day	19% 16% 27% 26% 10% 2	460
	11th to 20th	Day	17% 16% 22% 27% 15% 4	460
	21st to end	Day	16% 21% 25% 26% 12%	506
April	1st to 10th	Day	23% 16% 23% 22% 12% 4	460
	11th to 20th	Day	17% 19% 28% 20% 10% 6%	452
	21st to end	Day	11% 21% 25% 23% 15% 5%	460
May	1st to 10th	Day	13% 17% 26% 24% 15% 5%	463
	11th to 20th	Day	16% 12% 25% 24% 15% 8%	488
	21st to end	Day	14% 10% 21% 28% 19% 8%	529
June	1st to 10th	Day	10% 14% 25% 23% 20% 9%	490
	11th to 20th	Day	9% 18% 27% 28% 14% 4	490
	21st to end	Day	4 9% 24% 31% 24% 8%	490
July	1st to 10th	Day	2 7% 24% 33% 25% 8%	486
	11th to 20th	Day	2 8% 25% 27% 27% 12%	484
	21st to end	Day	1 5% 24% 27% 27% 14%	531
August	1st to 10th	Day	2 5% 21% 34% 24% 14%	487
	11th to 20th	Day	1 5% 18% 28% 29% 18%	477
	21st to end	Day	4 7% 21% 28% 27% 12%	539
September	1st to 10th	Day	2 6% 23% 25% 29% 16%	490
	11th to 20th	Day	6% 7% 21% 28% 28% 9%	490
	21st to end	Day	12% 9% 18% 27% 27% 7%	490
October	1st to 10th	Day	9% 10% 21% 29% 22% 9%	490
	11th to 20th	Day	12% 11% 20% 23% 27% 7%	487
	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% 17% 1	744
	21st to end	Night	17% 11% 26% 35% 11%	628
March	1st to 10th	Night	16% 9% 27% 34% 13% 1	760
	11th to 20th	Night	11% 9% 23% 38% 17% 2	760
	21st to end	Night	10% 11% 28% 35% 15% 1	836
April	1st to 10th	Night	17% 8% 22% 34% 19% 1	760
	11th to 20th	Night	11% 9% 27% 34% 17% 2	751
	21st to end	Night	14% 8% 23% 36% 18% 1	678
May	1st to 10th	Night	11% 5% 24% 38% 20% 1	380
	11th to 20th	Night	12% 4 17% 41% 25% 1	374
	21st to end	Night	9% 5% 16% 44% 25% 1	411
June	1st to 10th	Night	13% 5% 16% 46% 19% 1	380
	11th to 20th	Night	8% 4 23% 44% 20% 1	380
	21st to end	Night	7% 1 14% 51% 27% 1	380
July	1st to 10th	Night	3 9% 60% 27% 1	370
	11th to 20th	Night	1 17% 58% 23% 1	368
	21st to end	Night	1 10% 52% 35% 2	416
August	1st to 10th	Night	1 1 6% 52% 36% 4	463
	11th to 20th	Night	2 1 6% 39% 46% 7%	575
	21st to end	Night	2 3 16% 45% 32% 2	836
September	1st to 10th	Night	2 2 16% 43% 34% 4	760
	11th to 20th	Night	5% 2 12% 41% 34% 6%	760
	21st to end	Night	9% 3 13% 38% 32% 5%	760
October	1st to 10th	Night	11% 3 17% 40% 26% 3	760
	11th to 20th	Night	12% 5% 17% 37% 26% 4	758
	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

Page generated at 2024-10-17 10:09:43. Version ac07

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