Star Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Star Valley clear sky chart from 2005-11-06 to 2024-02-10.

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	8% 12% 4 7% 5% 3 4 4 5% 6% 40%	78910
	Night	8% 14% 5% 7% 5% 2 4 4 5% 6% 40%	80116
Transparency	Day	43% 6% 11% 19% 15% 6%	78622
	Night	44% 6% 12% 20% 13% 5%	79925
Seeing	Day	15% 14% 27% 26% 14% 4	14514
	Night	15% 6% 20% 39% 18% 2	24324

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	6% 22% 11% 14% 6% 3 3 3 6% 5% 22%	2702
	11th to 20th	Day	9% 22% 8% 14% 5% 3 2 3 3 4 27%	2860
	21st to end	Day	7% 30% 7% 9% 5% 2 3 3 5% 4 25%	3146
February	1st to 10th	Day	11% 25% 8% 11% 6% 2 4 3 3 5% 21%	1701
	11th to 20th	Day	8% 21% 8% 12% 7% 2 3 4 4 5% 26%	1575
	21st to end	Day	8% 20% 10% 16% 6% 3 4 4 3 4 21%	1448
March	1st to 10th	Day	8% 19% 7% 12% 6% 3 4 3 4 5% 29%	1939
	11th to 20th	Day	8% 15% 6% 7% 5% 4 5% 5% 6% 8% 31%	1980
	21st to end	Day	10% 22% 7% 11% 6% 3 4 4 5% 6% 22%	2178
April	1st to 10th	Day	13% 17% 6% 8% 5% 3 4 4 4 7% 28%	2056
	11th to 20th	Day	10% 15% 5% 9% 7% 4 5% 4 4 6% 30%	2261
	21st to end	Day	10% 16% 5% 8% 6% 4 4 5% 5% 6% 32%	2340
May	1st to 10th	Day	9% 11% 5% 9% 8% 3 6% 5% 5% 7% 33%	2340
	11th to 20th	Day	9% 7% 3 7% 7% 4 5% 6% 7% 9% 35%	2322
	21st to end	Day	14% 11% 4 8% 8% 4 6% 5% 6% 6% 27%	2724
June	1st to 10th	Day	10% 7% 2 6% 5% 3 4 5% 7% 8% 44%	2520
	11th to 20th	Day	9% 7% 3 5% 4 3 5% 5% 5% 7% 48%	2649
	21st to end	Day	3 2 1 3 4 2 4 4 5% 7% 65%	2700
July	1st to 10th	Day	2 3 1 3 3 2 4 5% 5% 9% 63%	2700
	11th to 20th	Day	2 2 2 3 4 2 4 4 4 7% 65%	2386
	21st to end	Day	3 4 2 5% 4 3 5% 5% 5% 7% 59%	2545
August	1st to 10th	Day	5% 4 2 5% 5% 3 5% 6% 6% 7% 54%	2328
	11th to 20th	Day	3 3 2 4 4 3 4 5% 5% 6% 64%	2299
	21st to end	Day	5% 3 1 3 4 2 4 5% 5% 7% 59%	2551
September	1st to 10th	Day	5% 4 2 4 4 1 4 3 5% 6% 62%	2124
	11th to 20th	Day	7% 5% 2 4 3 2 3 4 4 7% 58%	1980
	21st to end	Day	9% 4 2 4 4 2 3 3 4 5% 60%	1980
October	1st to 10th	Day	12% 9% 3 6% 6% 3 4 4 5% 5% 44%	1846
	11th to 20th	Day	11% 10% 3 4 4 2 3 5% 4 5% 48%	1800
	21st to end	Day	11% 11% 3 6% 4 3 3 4 5% 7% 44%	1958
November	1st to 10th	Day	15% 13% 6% 7% 3 2 3 3 4 5% 39%	1674
	11th to 20th	Day	12% 18% 4 8% 4 2 2 4 3 5% 36%	1538
	21st to end	Day	9% 16% 7% 8% 4 2 3 4 3 5% 38%	1520
December	1st to 10th	Day	11% 20% 7% 10% 7% 3 3 2 3 5% 29%	1520
	11th to 20th	Day	11% 21% 9% 11% 5% 3 4 4 4 6% 23%	1926
	21st to end	Day	8% 15% 6% 10% 6% 3 4 6% 7% 7% 28%	2794
January	1st to 10th	Night	6% 18% 10% 14% 7% 2 3 3 6% 7% 24%	4280
	11th to 20th	Night	8% 25% 8% 16% 6% 2 2 2 3 4 24%	4110
	21st to end	Night	9% 32% 7% 8% 4 2 3 3 4 4 24%	4521
February	1st to 10th	Night	8% 25% 7% 11% 6% 3 4 4 4 5% 23%	2463
	11th to 20th	Night	9% 19% 8% 10% 5% 2 4 4 4 4 31%	2272
	21st to end	Night	7% 22% 9% 13% 5% 3 5% 3 4 4 23%	1806
March	1st to 10th	Night	9% 19% 8% 10% 5% 3 4 3 5% 6% 28%	2021
	11th to 20th	Night	7% 14% 4 8% 5% 3 4 5% 5% 7% 38%	1980
	21st to end	Night	10% 19% 5% 9% 5% 3 3 5% 5% 6% 30%	2178
April	1st to 10th	Night	11% 15% 4 6% 5% 3 4 4 5% 6% 35%	1903
	11th to 20th	Night	10% 12% 5% 8% 4 3 5% 5% 5% 7% 37%	1645
	21st to end	Night	11% 10% 3 5% 4 3 3 4 5% 7% 45%	1620
May	1st to 10th	Night	11% 9% 3 5% 6% 3 3 4 6% 8% 42%	1620
	11th to 20th	Night	9% 5% 2 5% 5% 3 4 5% 7% 11% 43%	1573
	21st to end	Night	13% 8% 3 6% 6% 3 6% 6% 7% 8% 35%	1552
June	1st to 10th	Night	8% 5% 3 5% 5% 3 5% 4 6% 10% 47%	1440
	11th to 20th	Night	8% 5% 2 3 4 3 3 5% 5% 8% 54%	1305
	21st to end	Night	3 2 1 3 2 2 2 4 4 6% 72%	1260
July	1st to 10th	Night	1 1 1 2 3 3 5% 6% 7% 10% 62%	1260
	11th to 20th	Night	1 1 1 3 2 3 4 4 5% 6% 71%	1566
	21st to end	Night	1 2 1 3 3 2 4 5% 6% 7% 65%	1773
August	1st to 10th	Night	4 4 1 4 4 2 3 5% 7% 8% 58%	1611
	11th to 20th	Night	2 3 1 2 3 2 3 4 6% 9% 65%	1602
	21st to end	Night	4 3 1 3 3 1 3 3 5% 8% 65%	1804
September	1st to 10th	Night	5% 2 1 4 3 2 3 3 4 7% 67%	1831
	11th to 20th	Night	6% 4 1 3 3 2 3 4 5% 6% 62%	1980
	21st to end	Night	9% 4 1 3 3 2 2 3 3 5% 63%	1980
October	1st to 10th	Night	13% 7% 3 4 4 3 3 4 4 6% 49%	2114
	11th to 20th	Night	11% 9% 2 3 4 2 3 3 4 5% 54%	2160
	21st to end	Night	10% 10% 2 4 3 2 3 4 4 6% 51%	2395
November	1st to 10th	Night	15% 13% 4 6% 5% 2 4 4 4 6% 38%	2405
	11th to 20th	Night	12% 14% 3 5% 4 2 5% 5% 5% 6% 39%	2622
	21st to end	Night	8% 15% 6% 6% 4 3 4 3 4 6% 40%	2660
December	1st to 10th	Night	11% 19% 7% 10% 5% 3 3 3 4 5% 30%	2660
	11th to 20th	Night	13% 20% 7% 11% 6% 3 4 3 3 4 26%	3271
	21st to end	Night	8% 18% 6% 10% 6% 3 4 4 5% 8% 27%	4873

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	62% 6% 11% 17% 3 1	2703
	11th to 20th	Day	61% 5% 12% 12% 7% 2	2860
	21st to end	Day	61% 6% 11% 14% 8% 1	3146
February	1st to 10th	Day	67% 5% 10% 13% 5% 1	1701
	11th to 20th	Day	62% 5% 11% 14% 6% 2	1584
	21st to end	Day	66% 5% 9% 13% 5% 2	1448
March	1st to 10th	Day	59% 5% 12% 16% 7% 1	1939
	11th to 20th	Day	49% 7% 16% 18% 8% 1	1980
	21st to end	Day	63% 6% 12% 15% 4	2178
April	1st to 10th	Day	56% 6% 12% 15% 9% 2	2056
	11th to 20th	Day	55% 5% 10% 21% 7% 2	2264
	21st to end	Day	52% 6% 11% 23% 9%	2340
May	1st to 10th	Day	49% 6% 11% 21% 12% 1	2340
	11th to 20th	Day	42% 7% 13% 27% 10% 1	2325
	21st to end	Day	54% 9% 13% 18% 7%	2724
June	1st to 10th	Day	37% 7% 14% 26% 15% 2	2520
	11th to 20th	Day	35% 5% 11% 20% 19% 10%	2649
	21st to end	Day	18% 4 7% 22% 35% 15%	2700
July	1st to 10th	Day	17% 5% 7% 19% 35% 17%	2626
	11th to 20th	Day	19% 4 7% 15% 28% 26%	2314
	21st to end	Day	23% 5% 8% 14% 28% 23%	2404
August	1st to 10th	Day	26% 7% 9% 17% 25% 17%	2313
	11th to 20th	Day	21% 4 7% 19% 32% 16%	2299
	21st to end	Day	23% 4 8% 17% 31% 16%	2551
September	1st to 10th	Day	23% 4 8% 16% 30% 19%	2124
	11th to 20th	Day	26% 5% 9% 21% 28% 11%	1980
	21st to end	Day	28% 4 9% 27% 29% 4	1980
October	1st to 10th	Day	43% 4 9% 24% 15% 3	1846
	11th to 20th	Day	37% 5% 15% 28% 11% 3	1800
	21st to end	Day	40% 6% 15% 24% 14% 1	1958
November	1st to 10th	Day	49% 4 14% 20% 10% 2	1674
	11th to 20th	Day	51% 5% 15% 17% 10% 1	1538
	21st to end	Day	50% 5% 15% 19% 10% 1	1520
December	1st to 10th	Day	59% 7% 11% 13% 8% 3	1520
	11th to 20th	Day	61% 7% 13% 16% 4	1924
	21st to end	Day	50% 8% 12% 16% 11% 3	2794
January	1st to 10th	Night	59% 6% 11% 18% 5%	4280
	11th to 20th	Night	66% 5% 10% 14% 4 1	4110
	21st to end	Night	62% 7% 11% 13% 6% 1	4521
February	1st to 10th	Night	65% 7% 10% 13% 5%	2463
	11th to 20th	Night	56% 5% 11% 19% 8% 1	2273
	21st to end	Night	64% 5% 12% 12% 5% 2	1806
March	1st to 10th	Night	58% 5% 11% 19% 7%	2021
	11th to 20th	Night	44% 8% 14% 24% 9% 2	1980
	21st to end	Night	55% 7% 14% 19% 4 1	2178
April	1st to 10th	Night	49% 7% 15% 15% 11% 3	1903
	11th to 20th	Night	47% 6% 14% 22% 10% 2	1645
	21st to end	Night	39% 6% 16% 28% 11%	1620
May	1st to 10th	Night	38% 6% 13% 29% 13% 1	1620
	11th to 20th	Night	32% 8% 17% 28% 13% 1	1574
	21st to end	Night	42% 9% 18% 23% 7% 1	1552
June	1st to 10th	Night	32% 8% 17% 27% 15% 1	1440
	11th to 20th	Night	27% 5% 13% 25% 20% 9%	1305
	21st to end	Night	13% 4 8% 22% 38% 15%	1260
July	1st to 10th	Night	16% 4 11% 23% 30% 16%	1225
	11th to 20th	Night	13% 3 6% 20% 30% 28%	1515
	21st to end	Night	16% 4 9% 17% 30% 24%	1674
August	1st to 10th	Night	22% 5% 11% 19% 25% 19%	1602
	11th to 20th	Night	15% 4 6% 22% 34% 18%	1602
	21st to end	Night	18% 4 8% 20% 31% 19%	1804
September	1st to 10th	Night	19% 4 7% 17% 31% 22%	1831
	11th to 20th	Night	23% 5% 11% 20% 29% 12%	1980
	21st to end	Night	26% 3 9% 27% 31% 5%	1980
October	1st to 10th	Night	37% 5% 11% 25% 17% 4	2114
	11th to 20th	Night	34% 4 13% 31% 16% 3	2160
	21st to end	Night	34% 5% 16% 29% 15% 1	2395
November	1st to 10th	Night	47% 6% 13% 22% 10% 2	2405
	11th to 20th	Night	46% 5% 17% 22% 9% 1	2622
	21st to end	Night	46% 5% 15% 21% 10% 2	2660
December	1st to 10th	Night	58% 6% 15% 13% 7% 2	2660
	11th to 20th	Night	62% 6% 12% 15% 5%	3272
	21st to end	Night	52% 8% 11% 17% 9% 2	4873

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	24% 10% 19% 28% 17% 3	270
	11th to 20th	Day	21% 9% 23% 30% 14% 3	270
	21st to end	Day	17% 12% 24% 35% 10% 2	297
February	1st to 10th	Day	28% 19% 26% 19% 7% 1	267
	11th to 20th	Day	19% 18% 30% 24% 8% 2	240
	21st to end	Day	21% 25% 28% 19% 6% 1	314
March	1st to 10th	Day	25% 20% 27% 23% 5% 1	420
	11th to 20th	Day	15% 20% 31% 24% 8% 1	420
	21st to end	Day	24% 24% 32% 16% 4	462
April	1st to 10th	Day	30% 18% 26% 18% 7% 1	420
	11th to 20th	Day	26% 26% 28% 14% 5% 1	412
	21st to end	Day	25% 18% 24% 21% 9% 3	420
May	1st to 10th	Day	15% 21% 29% 25% 9% 1	423
	11th to 20th	Day	14% 17% 29% 23% 13% 2	469
	21st to end	Day	18% 11% 21% 26% 18% 5%	679
June	1st to 10th	Day	12% 12% 26% 26% 20% 4	630
	11th to 20th	Day	14% 16% 30% 26% 13% 2	630
	21st to end	Day	4 11% 27% 33% 20% 5%	630
July	1st to 10th	Day	3 9% 27% 34% 23% 5%	621
	11th to 20th	Day	3 11% 41% 27% 15% 3	474
	21st to end	Day	3 11% 30% 30% 20% 7%	487
August	1st to 10th	Day	6% 8% 35% 30% 17% 4	447
	11th to 20th	Day	3 11% 29% 30% 19% 8%	437
	21st to end	Day	7% 11% 26% 31% 19% 6%	495
September	1st to 10th	Day	5% 13% 28% 30% 16% 8%	450
	11th to 20th	Day	11% 16% 27% 23% 15% 8%	450
	21st to end	Day	11% 12% 24% 29% 18% 5%	450
October	1st to 10th	Day	13% 11% 24% 28% 16% 9%	316
	11th to 20th	Day	16% 13% 16% 28% 19% 7%	270
	21st to end	Day	21% 12% 25% 27% 13% 2	297
November	1st to 10th	Day	29% 9% 22% 23% 10% 7%	270
	11th to 20th	Day	21% 10% 26% 26% 13% 3	270
	21st to end	Day	16% 10% 24% 34% 13% 3	270
December	1st to 10th	Day	22% 10% 23% 30% 13% 3	270
	11th to 20th	Day	27% 13% 26% 24% 10% 1	270
	21st to end	Day	26% 11% 27% 21% 11% 4	297
January	1st to 10th	Night	20% 10% 21% 37% 13% 1	865
	11th to 20th	Night	20% 8% 24% 32% 14% 2	760
	21st to end	Night	21% 7% 23% 37% 11% 2	836
February	1st to 10th	Night	20% 9% 27% 36% 8% 1	758
	11th to 20th	Night	18% 8% 30% 33% 10% 2	704
	21st to end	Night	18% 10% 29% 34% 9%	592
March	1st to 10th	Night	17% 9% 28% 37% 8% 1	720
	11th to 20th	Night	13% 8% 22% 41% 15% 1	720
	21st to end	Night	16% 9% 24% 37% 12% 1	792
April	1st to 10th	Night	19% 10% 23% 37% 12% 1	643
	11th to 20th	Night	16% 10% 28% 36% 10%	533
	21st to end	Night	15% 8% 21% 34% 20% 1	540
May	1st to 10th	Night	14% 8% 20% 37% 20% 1	540
	11th to 20th	Night	12% 3 19% 37% 27% 1	531
	21st to end	Night	15% 6% 17% 38% 22% 3	584
June	1st to 10th	Night	9% 7% 20% 37% 25% 1	540
	11th to 20th	Night	10% 5% 22% 43% 20%	405
	21st to end	Night	4 1 10% 49% 32% 3	360
July	1st to 10th	Night	2 1 7% 48% 40% 2	350
	11th to 20th	Night	2 2 11% 54% 31%	505
	21st to end	Night	2 9% 47% 41% 2	591
August	1st to 10th	Night	5% 2 9% 47% 34% 2	537
	11th to 20th	Night	3 1 8% 49% 37% 3	534
	21st to end	Night	5% 3 11% 44% 34% 3	594
September	1st to 10th	Night	6% 3 11% 44% 33% 3	571
	11th to 20th	Night	8% 2 13% 39% 33% 5%	720
	21st to end	Night	11% 3 13% 40% 28% 5%	720
October	1st to 10th	Night	16% 5% 15% 39% 23% 3	720
	11th to 20th	Night	16% 5% 16% 37% 22% 4	720
	21st to end	Night	17% 4 17% 45% 15% 3	792
November	1st to 10th	Night	19% 7% 20% 36% 16% 2	740
	11th to 20th	Night	19% 9% 23% 38% 10% 1	912
	21st to end	Night	16% 7% 21% 39% 14% 3	950
December	1st to 10th	Night	22% 7% 26% 35% 9%	950
	11th to 20th	Night	22% 9% 24% 38% 8%	950
	21st to end	Night	21% 11% 25% 31% 10% 2	1045

Page generated at 2024-02-07 04:11:58. Version ac07

Copyright 2024 Attilla Danko