Scenic Vista Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Scenic Vista Park clear sky chart from 2005-11-06 to 2024-11-28.

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% 11% 4 8% 5% 5% 5% 4 5% 7% 31%	101236
	Night	16% 12% 4 8% 5% 4 4 3 5% 6% 32%	98218
Transparency	Day	49% 7% 12% 20% 11% 1	104899
	Night	50% 6% 11% 20% 11% 2	102694
Seeing	Day	22% 15% 28% 20% 11% 4	14729
	Night	22% 13% 27% 25% 12% 1	24523

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% 24% 7% 12% 5% 3 4 2 3 5% 17%	2836
	11th to 20th	Day	13% 23% 9% 13% 6% 4 3 2 4 5% 17%	2840
	21st to end	Day	25% 21% 9% 12% 5% 4 3 3 3 4 11%	3124
February	1st to 10th	Day	17% 19% 5% 11% 7% 5% 3 3 4 4 23%	1710
	11th to 20th	Day	15% 16% 6% 13% 6% 4 4 3 4 6% 22%	1680
	21st to end	Day	18% 16% 5% 10% 5% 4 4 3 5% 6% 25%	1570
March	1st to 10th	Day	21% 14% 5% 9% 4 4 4 3 4 6% 26%	3425
	11th to 20th	Day	13% 11% 5% 10% 6% 5% 5% 3 4 5% 34%	3480
	21st to end	Day	20% 11% 3 8% 4 4 4 3 5% 6% 30%	3815
April	1st to 10th	Day	14% 14% 3 8% 5% 4 4 4 5% 8% 31%	2156
	11th to 20th	Day	17% 12% 3 7% 4 4 4 4 5% 6% 33%	2347
	21st to end	Day	20% 11% 3 7% 5% 4 4 3 5% 6% 32%	2470
May	1st to 10th	Day	22% 10% 3 8% 5% 5% 5% 4 5% 6% 27%	4082
	11th to 20th	Day	19% 9% 4 7% 5% 5% 5% 4 5% 7% 31%	4081
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 10% 37%	4621
June	1st to 10th	Day	13% 8% 3 8% 5% 5% 5% 4 6% 9% 34%	2660
	11th to 20th	Day	13% 7% 3 7% 6% 5% 5% 4 7% 9% 34%	2660
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 5% 7% 10% 37%	2660
July	1st to 10th	Day	9% 6% 3 7% 5% 4 5% 4 7% 10% 39%	4169
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 7% 11% 39%	4120
	21st to end	Day	11% 6% 3 8% 5% 5% 6% 5% 7% 9% 35%	4466
August	1st to 10th	Day	14% 7% 3 8% 6% 6% 6% 5% 7% 9% 30%	4104
	11th to 20th	Day	12% 6% 2 7% 6% 6% 7% 5% 7% 9% 33%	4044
	21st to end	Day	7% 5% 2 7% 5% 7% 5% 5% 7% 9% 40%	4382
September	1st to 10th	Day	13% 6% 3 7% 4 4 4 3 5% 7% 45%	2230
	11th to 20th	Day	10% 7% 2 5% 4 4 5% 5% 6% 9% 43%	2090
	21st to end	Day	20% 8% 3 7% 5% 3 4 4 5% 6% 35%	2090
October	1st to 10th	Day	15% 7% 2 7% 5% 4 4 4 5% 8% 40%	1932
	11th to 20th	Day	18% 10% 3 7% 5% 4 4 4 5% 6% 34%	1900
	21st to end	Day	22% 11% 4 7% 5% 4 4 3 5% 6% 31%	2090
November	1st to 10th	Day	11% 9% 3 6% 5% 5% 4 4 5% 6% 42%	1819
	11th to 20th	Day	17% 15% 4 7% 5% 4 4 3 4 6% 30%	1727
	21st to end	Day	17% 17% 7% 8% 4 4 4 3 6% 6% 23%	1576
December	1st to 10th	Day	20% 20% 6% 11% 5% 4 4 3 4 4 18%	1520
	11th to 20th	Day	18% 18% 7% 14% 5% 3 3 3 4 6% 18%	1910
	21st to end	Day	25% 24% 6% 11% 5% 4 3 3 4 5% 12%	2850
January	1st to 10th	Night	16% 22% 8% 13% 5% 4 4 3 4 5% 16%	4109
	11th to 20th	Night	15% 20% 7% 17% 6% 5% 5% 3 4 4 13%	4120
	21st to end	Night	27% 18% 8% 13% 6% 3 3 2 2 3 15%	4532
February	1st to 10th	Night	20% 15% 5% 12% 6% 4 4 3 4 5% 23%	2470
	11th to 20th	Night	17% 14% 6% 12% 6% 5% 4 3 4 5% 23%	2384
	21st to end	Night	20% 14% 5% 13% 6% 3 4 4 5% 4 23%	1884
March	1st to 10th	Night	23% 13% 4 7% 4 4 3 3 3 5% 32%	3428
	11th to 20th	Night	17% 13% 6% 8% 3 4 4 3 5% 6% 32%	3480
	21st to end	Night	19% 11% 3 7% 5% 4 3 3 4 5% 37%	3817
April	1st to 10th	Night	16% 14% 3 6% 4 4 5% 3 5% 7% 33%	2023
	11th to 20th	Night	16% 10% 3 7% 6% 4 4 4 6% 7% 34%	1798
	21st to end	Night	16% 10% 2 8% 5% 4 3 4 6% 8% 35%	1710
May	1st to 10th	Night	26% 10% 3 7% 5% 4 4 3 5% 7% 27%	2813
	11th to 20th	Night	17% 10% 3 7% 4 4 4 3 5% 7% 36%	2812
	21st to end	Night	9% 6% 2 5% 4 4 4 5% 7% 10% 43%	2930
June	1st to 10th	Night	9% 7% 3 7% 5% 5% 5% 4 6% 8% 43%	1520
	11th to 20th	Night	11% 5% 3 6% 5% 4 3 4 6% 11% 43%	1520
	21st to end	Night	9% 6% 2 6% 4 5% 6% 5% 6% 8% 43%	1520
July	1st to 10th	Night	9% 7% 3 7% 5% 4 5% 4 5% 9% 42%	2771
	11th to 20th	Night	10% 5% 2 5% 4 5% 4 4 7% 9% 46%	2840
	21st to end	Night	8% 7% 3 8% 5% 5% 5% 4 6% 7% 43%	3087
August	1st to 10th	Night	12% 9% 3 8% 4 5% 5% 4 6% 8% 37%	2825
	11th to 20th	Night	12% 8% 3 6% 4 3 4 4 6% 7% 43%	2785
	21st to end	Night	7% 4 2 7% 5% 5% 5% 5% 7% 8% 44%	3242
September	1st to 10th	Night	13% 5% 2 6% 3 3 4 4 4 6% 50%	1947
	11th to 20th	Night	9% 4 2 5% 3 3 3 4 6% 8% 53%	2090
	21st to end	Night	17% 8% 2 6% 4 4 3 4 5% 6% 41%	2090
October	1st to 10th	Night	14% 6% 2 6% 4 4 3 3 5% 8% 45%	2247
	11th to 20th	Night	16% 8% 3 7% 5% 5% 5% 4 4 8% 36%	2280
	21st to end	Night	22% 11% 3 6% 4 3 3 3 4 7% 35%	2508
November	1st to 10th	Night	13% 8% 3 6% 4 4 4 3 6% 6% 43%	2474
	11th to 20th	Night	17% 13% 4 8% 5% 4 4 3 5% 6% 31%	2670
	21st to end	Night	19% 14% 5% 8% 5% 3 4 3 5% 6% 27%	2759
December	1st to 10th	Night	21% 18% 7% 9% 5% 4 4 3 4 5% 19%	2660
	11th to 20th	Night	18% 21% 6% 9% 5% 4 4 3 4 5% 22%	3285
	21st to end	Night	25% 21% 7% 10% 5% 3 4 3 4 5% 13%	4788

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	69% 6% 10% 12% 4	2837
	11th to 20th	Day	71% 4 9% 12% 4	2840
	21st to end	Day	78% 5% 8% 7% 2	3124
February	1st to 10th	Day	66% 5% 9% 13% 7% 1	1710
	11th to 20th	Day	64% 6% 9% 15% 7%	1689
	21st to end	Day	60% 5% 11% 16% 7% 2	1570
March	1st to 10th	Day	59% 5% 10% 20% 5%	3425
	11th to 20th	Day	49% 8% 12% 22% 8% 1	3480
	21st to end	Day	53% 6% 11% 17% 12% 1	3815
April	1st to 10th	Day	51% 7% 12% 18% 11% 1	2156
	11th to 20th	Day	50% 7% 11% 16% 14% 2	2347
	21st to end	Day	52% 7% 11% 20% 10% 2	2470
May	1st to 10th	Day	55% 8% 10% 18% 8% 1	4120
	11th to 20th	Day	50% 8% 12% 19% 9% 1	4085
	21st to end	Day	39% 10% 14% 21% 13% 3	4635
June	1st to 10th	Day	44% 8% 14% 21% 12% 1	2660
	11th to 20th	Day	44% 8% 13% 22% 12% 1	2660
	21st to end	Day	40% 9% 12% 24% 13% 1	2660
July	1st to 10th	Day	38% 8% 14% 22% 15% 3	4104
	11th to 20th	Day	35% 8% 13% 27% 16% 1	4051
	21st to end	Day	41% 9% 14% 19% 17% 1	4324
August	1st to 10th	Day	47% 9% 13% 21% 10%	4091
	11th to 20th	Day	42% 9% 13% 28% 8% 1	4083
	21st to end	Day	37% 9% 14% 28% 11% 2	4382
September	1st to 10th	Day	39% 7% 11% 21% 19% 3	2230
	11th to 20th	Day	35% 7% 16% 25% 16% 1	2090
	21st to end	Day	49% 7% 10% 22% 12% 1	2090
October	1st to 10th	Day	32% 6% 12% 29% 20% 1	3205
	11th to 20th	Day	46% 6% 10% 19% 14% 4	3140
	21st to end	Day	39% 6% 12% 26% 16% 1	3428
November	1st to 10th	Day	42% 7% 12% 22% 16% 2	1819
	11th to 20th	Day	55% 5% 10% 18% 9% 3	1727
	21st to end	Day	60% 6% 11% 15% 6% 1	1576
December	1st to 10th	Day	70% 5% 10% 11% 3	1520
	11th to 20th	Day	67% 5% 9% 15% 4	1906
	21st to end	Day	76% 6% 9% 7% 2	2850
January	1st to 10th	Night	69% 6% 10% 11% 3	4109
	11th to 20th	Night	73% 6% 9% 10% 2	4120
	21st to end	Night	77% 3 6% 11% 2	4532
February	1st to 10th	Night	64% 5% 10% 15% 6%	2470
	11th to 20th	Night	63% 4 10% 15% 7%	2386
	21st to end	Night	63% 6% 9% 12% 9% 1	1884
March	1st to 10th	Night	55% 4 10% 22% 9%	3428
	11th to 20th	Night	50% 7% 15% 21% 6% 1	3480
	21st to end	Night	48% 6% 12% 22% 12% 1	3817
April	1st to 10th	Night	50% 6% 10% 18% 13% 2	2023
	11th to 20th	Night	46% 8% 12% 16% 15% 3	1798
	21st to end	Night	46% 6% 12% 19% 15% 2	1710
May	1st to 10th	Night	56% 7% 8% 18% 10% 2	2840
	11th to 20th	Night	45% 9% 12% 23% 10% 2	2813
	21st to end	Night	31% 10% 17% 26% 13% 4	2937
June	1st to 10th	Night	37% 9% 14% 23% 16% 2	1520
	11th to 20th	Night	35% 7% 16% 23% 16% 2	1520
	21st to end	Night	35% 10% 13% 24% 16% 1	1520
July	1st to 10th	Night	39% 7% 12% 22% 17% 3	2726
	11th to 20th	Night	31% 8% 15% 29% 16% 1	2786
	21st to end	Night	39% 8% 12% 17% 22% 3	2988
August	1st to 10th	Night	44% 8% 12% 23% 12% 1	2814
	11th to 20th	Night	38% 7% 12% 26% 15% 1	2812
	21st to end	Night	33% 9% 13% 30% 13% 2	3242
September	1st to 10th	Night	34% 8% 11% 23% 19% 5%	1947
	11th to 20th	Night	29% 7% 14% 26% 22% 2	2090
	21st to end	Night	43% 5% 12% 22% 18% 1	2090
October	1st to 10th	Night	32% 6% 9% 27% 24% 2	3754
	11th to 20th	Night	39% 6% 12% 23% 13% 7%	3779
	21st to end	Night	36% 4 10% 30% 18% 2	4120
November	1st to 10th	Night	40% 6% 13% 22% 16% 3	2474
	11th to 20th	Night	53% 5% 11% 19% 9% 3	2670
	21st to end	Night	58% 5% 12% 18% 6% 1	2759
December	1st to 10th	Night	68% 5% 10% 12% 5%	2660
	11th to 20th	Night	65% 5% 12% 15% 3	3288
	21st to end	Night	73% 6% 10% 9% 2	4788

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% 24% 27% 11% 4	270
	11th to 20th	Day	34% 30% 29% 5% 1	270
	21st to end	Day	29% 33% 29% 7% 2	297
February	1st to 10th	Day	35% 21% 34% 9% 1	270
	11th to 20th	Day	36% 27% 30% 6% 1	270
	21st to end	Day	40% 25% 27% 8%	225
March	1st to 10th	Day	28% 25% 29% 15% 3	450
	11th to 20th	Day	30% 22% 30% 12% 5% 1	460
	21st to end	Day	31% 22% 29% 15% 3 1	506
April	1st to 10th	Day	27% 24% 27% 13% 7% 2	460
	11th to 20th	Day	28% 18% 28% 16% 9% 2	452
	21st to end	Day	29% 16% 33% 15% 5% 2	460
May	1st to 10th	Day	28% 19% 27% 16% 7% 3	463
	11th to 20th	Day	22% 14% 32% 20% 8% 4	487
	21st to end	Day	16% 9% 27% 27% 16% 6%	529
June	1st to 10th	Day	15% 12% 31% 25% 13% 4	490
	11th to 20th	Day	18% 10% 26% 27% 15% 4	490
	21st to end	Day	14% 11% 32% 25% 14% 3	490
July	1st to 10th	Day	12% 7% 24% 26% 21% 11%	485
	11th to 20th	Day	10% 8% 29% 28% 18% 8%	484
	21st to end	Day	11% 7% 25% 32% 17% 8%	532
August	1st to 10th	Day	13% 7% 23% 29% 21% 8%	486
	11th to 20th	Day	15% 6% 22% 28% 19% 9%	479
	21st to end	Day	11% 5% 26% 28% 20% 10%	539
September	1st to 10th	Day	14% 9% 22% 27% 19% 9%	490
	11th to 20th	Day	11% 6% 20% 30% 22% 11%	490
	21st to end	Day	23% 12% 25% 20% 14% 5%	490
October	1st to 10th	Day	14% 11% 28% 26% 17% 5%	490
	11th to 20th	Day	23% 15% 31% 20% 9% 2	490
	21st to end	Day	30% 16% 31% 17% 6%	539
November	1st to 10th	Day	20% 21% 33% 14% 10% 2	357
	11th to 20th	Day	27% 20% 33% 13% 6% 2	263
	21st to end	Day	26% 24% 41% 9% 1	194
December	1st to 10th	Day	32% 28% 28% 7% 4 2	180
	11th to 20th	Day	29% 23% 33% 11% 3	180
	21st to end	Day	37% 24% 26% 10% 2	222
January	1st to 10th	Night	28% 22% 34% 13% 3	760
	11th to 20th	Night	31% 20% 31% 15% 3	760
	21st to end	Night	29% 22% 28% 18% 3	836
February	1st to 10th	Night	30% 18% 30% 20% 2	760
	11th to 20th	Night	28% 22% 36% 13% 2	743
	21st to end	Night	30% 21% 31% 16% 2	628
March	1st to 10th	Night	24% 20% 33% 20% 3	760
	11th to 20th	Night	27% 18% 27% 22% 5% 1	760
	21st to end	Night	27% 14% 34% 21% 4 1	836
April	1st to 10th	Night	25% 16% 31% 23% 6%	760
	11th to 20th	Night	23% 14% 33% 21% 9% 1	674
	21st to end	Night	22% 11% 35% 26% 7%	570
May	1st to 10th	Night	24% 9% 26% 31% 9% 1	570
	11th to 20th	Night	19% 10% 26% 30% 14% 1	561
	21st to end	Night	11% 4 24% 36% 22% 3	532
June	1st to 10th	Night	12% 5% 27% 40% 16%	380
	11th to 20th	Night	12% 6% 25% 40% 17% 1	380
	21st to end	Night	10% 3 28% 36% 22% 1	380
July	1st to 10th	Night	8% 3 18% 39% 24% 7%	512
	11th to 20th	Night	9% 3 21% 37% 27% 4	552
	21st to end	Night	11% 3 16% 39% 29% 2	624
August	1st to 10th	Night	11% 2 16% 39% 30% 2	567
	11th to 20th	Night	12% 3 14% 39% 27% 4	564
	21st to end	Night	10% 4 20% 31% 28% 6%	693
September	1st to 10th	Night	15% 5% 20% 31% 26% 4	760
	11th to 20th	Night	10% 5% 16% 36% 30% 4	760
	21st to end	Night	20% 8% 24% 26% 19% 4	760
October	1st to 10th	Night	17% 9% 23% 28% 21% 2	760
	11th to 20th	Night	21% 13% 30% 23% 12% 1	760
	21st to end	Night	26% 14% 28% 23% 8%	836
November	1st to 10th	Night	18% 15% 27% 30% 10%	780
	11th to 20th	Night	26% 18% 27% 20% 7% 1	800
	21st to end	Night	30% 16% 28% 21% 5%	789
December	1st to 10th	Night	32% 19% 27% 18% 4	760
	11th to 20th	Night	30% 18% 29% 19% 4	760
	21st to end	Night	31% 18% 32% 17% 2	836

Page generated at 2024-11-25 00:22:17. Version ac07

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