Summit Lake State Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Summit Lake State Recreation Area clear sky chart from 2005-11-06 to 2024-03-18.

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	12% 7% 3 6% 5% 3 4 5% 5% 7% 43%	78886
	Night	10% 7% 3 6% 5% 3 4 4 5% 7% 46%	80908
Transparency	Day	42% 3 13% 26% 14% 2	78609
	Night	39% 3 13% 27% 16% 2	80705
Seeing	Day	14% 9% 29% 30% 14% 3	14857
	Night	13% 8% 33% 34% 11% 1	24962

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	9% 12% 5% 15% 12% 4 4 4 4 6% 25%	2847
	11th to 20th	Day	8% 11% 5% 10% 7% 4 8% 5% 6% 7% 29%	2850
	21st to end	Day	9% 11% 6% 14% 8% 5% 5% 5% 4 6% 28%	3135
February	1st to 10th	Day	10% 11% 6% 9% 8% 4 5% 4 5% 8% 30%	1710
	11th to 20th	Day	9% 10% 4 8% 6% 3 4 5% 5% 5% 42%	1691
	21st to end	Day	11% 9% 3 8% 6% 4 4 4 5% 7% 40%	1570
March	1st to 10th	Day	10% 9% 4 6% 5% 3 5% 4 4 5% 44%	2046
	11th to 20th	Day	15% 10% 5% 5% 4 3 4 5% 5% 6% 39%	2057
	21st to end	Day	18% 13% 4 7% 5% 3 5% 5% 5% 5% 31%	2178
April	1st to 10th	Day	15% 8% 3 6% 5% 3 4 3 4 7% 41%	2033
	11th to 20th	Day	19% 9% 3 5% 5% 3 4 3 5% 6% 39%	2258
	21st to end	Day	20% 8% 3 5% 4 3 4 4 4 7% 38%	2340
May	1st to 10th	Day	18% 6% 2 5% 6% 3 5% 5% 6% 7% 37%	2340
	11th to 20th	Day	15% 8% 3 6% 5% 3 4 4 6% 6% 40%	2302
	21st to end	Day	16% 7% 3 6% 5% 3 6% 5% 6% 7% 36%	2635
June	1st to 10th	Day	9% 4 2 5% 5% 2 4 5% 5% 9% 49%	2520
	11th to 20th	Day	10% 4 2 4 5% 3 5% 5% 6% 9% 46%	2520
	21st to end	Day	8% 5% 2 4 5% 3 4 4 6% 9% 50%	2622
July	1st to 10th	Day	8% 4 1 4 4 3 5% 5% 6% 9% 51%	2421
	11th to 20th	Day	7% 3 2 4 4 2 4 5% 6% 8% 56%	2340
	21st to end	Day	5% 3 2 4 4 4 4 6% 7% 10% 52%	2546
August	1st to 10th	Day	9% 5% 2 6% 7% 4 5% 6% 7% 8% 42%	2328
	11th to 20th	Day	9% 5% 2 4 5% 2 4 5% 5% 8% 51%	2301
	21st to end	Day	9% 5% 2 3 4 2 3 5% 5% 8% 54%	2548
September	1st to 10th	Day	13% 4 2 4 4 2 4 5% 4 5% 52%	2089
	11th to 20th	Day	11% 5% 2 4 5% 3 4 3 4 7% 54%	1980
	21st to end	Day	11% 4 2 3 3 2 3 4 5% 7% 56%	1980
October	1st to 10th	Day	15% 5% 3 5% 5% 2 4 3 4 6% 49%	1846
	11th to 20th	Day	12% 5% 2 4 4 2 3 3 4 5% 56%	1800
	21st to end	Day	14% 8% 2 5% 4 2 3 4 4 5% 48%	1976
November	1st to 10th	Day	9% 5% 3 5% 4 2 4 4 4 6% 54%	1673
	11th to 20th	Day	10% 7% 3 7% 5% 3 4 4 5% 7% 45%	1627
	21st to end	Day	12% 7% 4 5% 4 3 3 3 6% 7% 45%	1520
December	1st to 10th	Day	10% 8% 4 6% 5% 3 4 4 4 7% 45%	1520
	11th to 20th	Day	8% 10% 4 6% 6% 4 5% 6% 6% 8% 37%	1918
	21st to end	Day	16% 10% 5% 14% 8% 3 4 4 5% 6% 25%	2819
January	1st to 10th	Night	8% 12% 4 15% 12% 4 5% 4 5% 5% 27%	4108
	11th to 20th	Night	6% 11% 4 8% 6% 3 8% 6% 9% 6% 33%	4120
	21st to end	Night	10% 12% 7% 11% 6% 4 4 5% 5% 6% 31%	4532
February	1st to 10th	Night	11% 10% 5% 7% 7% 3 4 4 4 5% 39%	2470
	11th to 20th	Night	8% 8% 3 7% 5% 3 5% 4 6% 7% 44%	2393
	21st to end	Night	9% 7% 3 7% 5% 3 4 3 5% 5% 49%	1884
March	1st to 10th	Night	10% 8% 4 5% 5% 3 4 4 5% 7% 46%	2133
	11th to 20th	Night	15% 9% 3 4 3 2 3 5% 3 7% 45%	2068
	21st to end	Night	17% 10% 4 7% 6% 3 4 5% 4 7% 33%	2178
April	1st to 10th	Night	13% 7% 2 5% 6% 3 4 4 5% 7% 45%	1926
	11th to 20th	Night	13% 7% 3 6% 5% 3 4 3 4 6% 46%	1649
	21st to end	Night	16% 6% 3 5% 5% 2 4 4 5% 7% 42%	1620
May	1st to 10th	Night	15% 5% 3 5% 4 3 4 5% 6% 9% 42%	1620
	11th to 20th	Night	13% 5% 2 5% 5% 3 4 4 6% 8% 46%	1593
	21st to end	Night	14% 5% 3 6% 5% 4 4 5% 5% 9% 40%	1638
June	1st to 10th	Night	7% 4 1 3 3 2 5% 5% 6% 9% 55%	1440
	11th to 20th	Night	8% 4 2 4 4 3 4 5% 5% 9% 52%	1440
	21st to end	Night	4 3 2 4 3 3 4 4 6% 8% 59%	1316
July	1st to 10th	Night	5% 3 2 3 4 2 4 4 5% 10% 57%	1511
	11th to 20th	Night	4 1 1 3 3 2 5% 4 6% 9% 62%	1620
	21st to end	Night	4 2 1 3 4 2 4 4 5% 10% 60%	1772
August	1st to 10th	Night	6% 4 2 4 5% 4 4 5% 7% 9% 51%	1611
	11th to 20th	Night	7% 4 1 4 3 2 4 3 6% 9% 58%	1600
	21st to end	Night	7% 4 2 3 4 3 3 4 6% 8% 56%	1808
September	1st to 10th	Night	9% 3 2 3 4 2 3 3 4 8% 58%	1867
	11th to 20th	Night	9% 3 1 3 4 1 3 4 6% 7% 59%	1980
	21st to end	Night	10% 4 1 4 4 2 3 3 4 5% 60%	1980
October	1st to 10th	Night	14% 6% 2 4 4 2 4 4 5% 6% 49%	2096
	11th to 20th	Night	13% 6% 2 4 3 2 2 2 4 5% 55%	2160
	21st to end	Night	15% 6% 2 4 3 2 3 3 4 6% 52%	2376
November	1st to 10th	Night	8% 4 2 4 4 2 4 4 5% 6% 58%	2405
	11th to 20th	Night	10% 5% 3 5% 4 2 3 4 5% 7% 52%	2550
	21st to end	Night	11% 7% 3 4 4 2 3 4 4 7% 50%	2660
December	1st to 10th	Night	8% 8% 4 7% 6% 3 3 4 5% 7% 45%	2660
	11th to 20th	Night	9% 8% 4 5% 5% 3 4 4 5% 7% 46%	3279
	21st to end	Night	16% 13% 7% 11% 5% 2 4 3 3 6% 31%	4845

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% 2 11% 17% 7%	2848
	11th to 20th	Day	55% 3 12% 24% 7%	2850
	21st to end	Day	56% 6% 14% 17% 7%	3135
February	1st to 10th	Day	53% 4 14% 19% 10% 1	1710
	11th to 20th	Day	45% 3 12% 24% 15% 2	1700
	21st to end	Day	44% 4 11% 24% 13% 3	1570
March	1st to 10th	Day	42% 3 12% 28% 12% 2	2046
	11th to 20th	Day	47% 3 11% 24% 13% 2	2057
	21st to end	Day	54% 4 15% 19% 7% 1	2178
April	1st to 10th	Day	45% 3 12% 27% 12% 1	2033
	11th to 20th	Day	46% 3 12% 23% 13% 2	2258
	21st to end	Day	47% 4 10% 27% 12%	2340
May	1st to 10th	Day	48% 3 14% 21% 14% 1	2340
	11th to 20th	Day	44% 4 13% 27% 11% 1	2306
	21st to end	Day	47% 4 15% 20% 11% 2	2635
June	1st to 10th	Day	33% 4 17% 30% 13% 3	2520
	11th to 20th	Day	34% 5% 13% 29% 17% 2	2520
	21st to end	Day	32% 4 14% 32% 15% 4	2622
July	1st to 10th	Day	29% 4 15% 33% 17% 2	2357
	11th to 20th	Day	27% 3 14% 31% 20% 6%	2271
	21st to end	Day	26% 5% 16% 32% 19% 2	2405
August	1st to 10th	Day	38% 5% 18% 25% 12% 2	2314
	11th to 20th	Day	32% 4 13% 34% 16% 1	2301
	21st to end	Day	29% 4 13% 28% 21% 5%	2548
September	1st to 10th	Day	33% 3 11% 30% 18% 5%	2089
	11th to 20th	Day	33% 2 9% 36% 18% 1	1980
	21st to end	Day	28% 3 10% 33% 24% 1	1980
October	1st to 10th	Day	38% 2 10% 28% 20% 2	1846
	11th to 20th	Day	33% 2 10% 28% 22% 5%	1800
	21st to end	Day	40% 2 13% 23% 18% 4	1976
November	1st to 10th	Day	31% 3 16% 27% 20% 3	1673
	11th to 20th	Day	40% 3 13% 27% 16% 1	1627
	21st to end	Day	41% 3 13% 28% 14% 2	1520
December	1st to 10th	Day	40% 3 15% 28% 11% 2	1520
	11th to 20th	Day	46% 3 18% 27% 6%	1915
	21st to end	Day	61% 2 11% 19% 6% 1	2819
January	1st to 10th	Night	59% 3 11% 17% 10% 1	4108
	11th to 20th	Night	48% 3 14% 24% 10% 1	4120
	21st to end	Night	53% 5% 13% 19% 9% 1	4532
February	1st to 10th	Night	48% 3 13% 22% 12% 2	2470
	11th to 20th	Night	40% 3 14% 25% 15% 3	2394
	21st to end	Night	38% 2 12% 26% 19% 3	1884
March	1st to 10th	Night	39% 4 11% 30% 14% 2	2133
	11th to 20th	Night	42% 4 9% 26% 17% 3	2068
	21st to end	Night	52% 4 13% 21% 8% 1	2178
April	1st to 10th	Night	40% 4 12% 25% 18% 2	1926
	11th to 20th	Night	42% 2 11% 27% 16% 2	1649
	21st to end	Night	42% 3 13% 25% 16% 1	1620
May	1st to 10th	Night	40% 4 14% 26% 15% 2	1620
	11th to 20th	Night	37% 5% 14% 26% 17% 1	1594
	21st to end	Night	42% 4 19% 19% 12% 3	1639
June	1st to 10th	Night	26% 4 15% 36% 15% 3	1440
	11th to 20th	Night	29% 4 14% 28% 20% 5%	1440
	21st to end	Night	24% 4 15% 34% 19% 3	1316
July	1st to 10th	Night	24% 3 16% 33% 21% 4	1466
	11th to 20th	Night	19% 4 18% 34% 19% 6%	1566
	21st to end	Night	20% 4 17% 34% 22% 3	1673
August	1st to 10th	Night	30% 3 17% 30% 17% 2	1601
	11th to 20th	Night	25% 3 16% 35% 20% 3	1600
	21st to end	Night	27% 4 13% 26% 21% 9%	1808
September	1st to 10th	Night	26% 3 10% 31% 23% 6%	1867
	11th to 20th	Night	25% 3 11% 37% 21% 3	1980
	21st to end	Night	29% 2 9% 31% 26% 4	1980
October	1st to 10th	Night	37% 2 10% 24% 24% 2	2096
	11th to 20th	Night	33% 3 8% 25% 26% 5%	2160
	21st to end	Night	36% 2 12% 25% 22% 3	2376
November	1st to 10th	Night	28% 2 15% 27% 23% 4	2405
	11th to 20th	Night	34% 2 13% 30% 18% 3	2550
	21st to end	Night	36% 3 11% 31% 18% 2	2660
December	1st to 10th	Night	40% 3 13% 31% 12% 1	2660
	11th to 20th	Night	39% 3 16% 34% 8%	3281
	21st to end	Night	58% 3 10% 22% 7% 1	4845

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	18% 12% 33% 26% 11% 1	270
	11th to 20th	Day	17% 11% 36% 29% 5% 1	270
	21st to end	Day	14% 8% 40% 28% 8% 1	297
February	1st to 10th	Day	16% 19% 33% 27% 5%	270
	11th to 20th	Day	16% 16% 32% 26% 8% 1	270
	21st to end	Day	18% 16% 39% 21% 5%	225
March	1st to 10th	Day	14% 17% 40% 22% 4 3	270
	11th to 20th	Day	24% 15% 33% 20% 8%	261
	21st to end	Day	34% 13% 30% 18% 3 2	264
April	1st to 10th	Day	19% 15% 39% 23% 3	293
	11th to 20th	Day	22% 15% 31% 24% 8% 1	536
	21st to end	Day	24% 15% 30% 20% 11% 1	600
May	1st to 10th	Day	22% 11% 30% 25% 10% 2	603
	11th to 20th	Day	19% 10% 28% 27% 13% 3	625
	21st to end	Day	19% 8% 26% 29% 15% 3	679
June	1st to 10th	Day	7% 6% 25% 38% 20% 6%	630
	11th to 20th	Day	9% 5% 32% 34% 17% 4	630
	21st to end	Day	9% 8% 29% 34% 17% 3	630
July	1st to 10th	Day	8% 3 19% 36% 26% 9%	621
	11th to 20th	Day	7% 4 22% 38% 22% 6%	618
	21st to end	Day	6% 4 18% 44% 27% 2	684
August	1st to 10th	Day	10% 3 21% 35% 26% 6%	626
	11th to 20th	Day	9% 4 22% 37% 24% 3	615
	21st to end	Day	10% 4 20% 40% 22% 5%	667
September	1st to 10th	Day	13% 5% 25% 38% 16% 3	379
	11th to 20th	Day	9% 5% 33% 32% 16% 6%	270
	21st to end	Day	13% 9% 30% 30% 15% 3	270
October	1st to 10th	Day	20% 5% 33% 23% 13% 6%	270
	11th to 20th	Day	13% 15% 37% 25% 8% 1	270
	21st to end	Day	18% 12% 35% 22% 11% 1	297
November	1st to 10th	Day	14% 12% 38% 23% 10% 3	270
	11th to 20th	Day	13% 14% 41% 24% 8%	270
	21st to end	Day	22% 11% 30% 29% 7% 1	270
December	1st to 10th	Day	10% 14% 37% 27% 10% 1	270
	11th to 20th	Day	16% 11% 33% 29% 10% 1	270
	21st to end	Day	23% 12% 39% 22% 3 1	297
January	1st to 10th	Night	13% 12% 35% 33% 6% 1	950
	11th to 20th	Night	14% 12% 36% 31% 7%	950
	21st to end	Night	17% 8% 38% 30% 7%	1045
February	1st to 10th	Night	18% 10% 36% 32% 4	950
	11th to 20th	Night	13% 11% 39% 33% 5%	919
	21st to end	Night	13% 11% 41% 29% 6%	628
March	1st to 10th	Night	13% 14% 38% 28% 7% 1	613
	11th to 20th	Night	20% 8% 38% 27% 7%	564
	21st to end	Night	21% 11% 35% 27% 5%	594
April	1st to 10th	Night	17% 13% 40% 26% 4	540
	11th to 20th	Night	15% 12% 39% 28% 5%	533
	21st to end	Night	19% 9% 33% 30% 8%	540
May	1st to 10th	Night	16% 9% 32% 35% 8%	540
	11th to 20th	Night	14% 9% 31% 35% 11%	531
	21st to end	Night	16% 6% 30% 35% 13% 1	584
June	1st to 10th	Night	8% 4 26% 45% 16% 1	540
	11th to 20th	Night	9% 4 34% 40% 13% 1	540
	21st to end	Night	4 3 33% 42% 18%	540
July	1st to 10th	Night	7% 2 18% 42% 30% 1	525
	11th to 20th	Night	3 2 21% 49% 24% 1	522
	21st to end	Night	5% 2 13% 55% 24%	591
August	1st to 10th	Night	7% 3 20% 42% 26% 2	537
	11th to 20th	Night	8% 2 19% 47% 23% 1	534
	21st to end	Night	8% 2 22% 42% 23% 3	594
September	1st to 10th	Night	11% 4 24% 39% 21% 1	540
	11th to 20th	Night	10% 2 30% 40% 16% 1	540
	21st to end	Night	10% 6% 33% 34% 15% 1	540
October	1st to 10th	Night	16% 7% 32% 32% 11% 1	656
	11th to 20th	Night	16% 11% 35% 29% 8%	720
	21st to end	Night	19% 11% 28% 31% 10%	792
November	1st to 10th	Night	9% 11% 35% 35% 9% 1	925
	11th to 20th	Night	14% 10% 40% 29% 6% 1	950
	21st to end	Night	15% 10% 36% 30% 9%	950
December	1st to 10th	Night	13% 11% 39% 31% 6%	950
	11th to 20th	Night	16% 9% 35% 33% 7%	950
	21st to end	Night	19% 11% 36% 28% 6%	1045

Page generated at 2024-03-15 13:01:39. Version ac07

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