Solon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Solon clear sky chart from 2005-11-06 to 2024-09-14.

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	16% 12% 4 9% 5% 4 4 4 5% 7% 30%	100498
	Night	17% 13% 5% 9% 5% 4 4 3 5% 6% 30%	97344
Transparency	Day	53% 4 11% 20% 10% 1	100310
	Night	55% 4 10% 19% 11% 1	97202
Seeing	Day	25% 14% 29% 19% 9% 3	14389
	Night	24% 14% 27% 24% 10% 1	24164

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% 23% 10% 15% 4 4 3 2 3 4 14%	2836
	11th to 20th	Day	14% 25% 8% 13% 7% 7% 3 2 4 4 11%	2840
	21st to end	Day	26% 20% 12% 16% 6% 3 3 2 3 3 6%	3124
February	1st to 10th	Day	16% 22% 6% 11% 8% 4 3 2 4 4 18%	1710
	11th to 20th	Day	15% 16% 6% 15% 9% 5% 4 3 4 4 18%	1705
	21st to end	Day	17% 17% 4 14% 5% 5% 4 3 5% 4 21%	1570
March	1st to 10th	Day	22% 12% 7% 9% 4 3 4 3 5% 6% 25%	3365
	11th to 20th	Day	13% 15% 6% 10% 6% 4 3 3 4 5% 31%	3480
	21st to end	Day	22% 13% 5% 10% 4 4 4 3 4 5% 27%	3815
April	1st to 10th	Day	16% 14% 4 7% 4 4 4 3 6% 6% 30%	2135
	11th to 20th	Day	19% 13% 3 6% 5% 3 5% 4 4 6% 32%	2404
	21st to end	Day	20% 13% 3 8% 3 4 3 4 4 5% 33%	2470
May	1st to 10th	Day	21% 9% 3 8% 5% 5% 4 4 5% 6% 30%	4082
	11th to 20th	Day	20% 9% 2 7% 5% 4 4 4 5% 8% 33%	4081
	21st to end	Day	13% 6% 2 7% 5% 4 5% 4 6% 8% 39%	4589
June	1st to 10th	Day	16% 7% 2 6% 5% 5% 5% 5% 6% 8% 36%	2660
	11th to 20th	Day	14% 7% 2 7% 5% 4 5% 4 7% 8% 38%	2660
	21st to end	Day	13% 6% 2 6% 5% 4 5% 4 7% 9% 39%	2660
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 4 7% 10% 38%	4155
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 7% 10% 42%	4120
	21st to end	Day	10% 6% 3 7% 5% 6% 6% 4 6% 8% 38%	4466
August	1st to 10th	Day	13% 8% 3 7% 5% 5% 5% 5% 7% 9% 34%	4104
	11th to 20th	Day	13% 6% 3 7% 5% 5% 6% 5% 7% 8% 34%	4044
	21st to end	Day	10% 5% 2 6% 5% 5% 6% 4 7% 10% 39%	4446
September	1st to 10th	Day	15% 6% 2 6% 4 4 4 4 6% 8% 41%	2192
	11th to 20th	Day	11% 6% 2 7% 5% 5% 5% 3 6% 9% 41%	2014
	21st to end	Day	20% 8% 3 6% 4 4 4 3 5% 6% 38%	1980
October	1st to 10th	Day	17% 7% 2 7% 5% 4 5% 3 5% 8% 37%	1854
	11th to 20th	Day	22% 11% 3 8% 3 5% 4 3 5% 6% 31%	1800
	21st to end	Day	25% 13% 3 8% 5% 4 4 3 5% 5% 25%	1980
November	1st to 10th	Day	14% 13% 4 8% 5% 3 4 4 5% 7% 35%	1672
	11th to 20th	Day	19% 18% 4 8% 4 3 3 4 4 6% 26%	1663
	21st to end	Day	19% 20% 6% 9% 5% 4 5% 3 5% 5% 17%	1520
December	1st to 10th	Day	17% 24% 8% 12% 6% 4 4 3 3 4 13%	1520
	11th to 20th	Day	19% 19% 9% 16% 5% 3 4 3 5% 5% 13%	1910
	21st to end	Day	24% 28% 8% 11% 4 4 3 2 3 3 9%	2872
January	1st to 10th	Night	15% 25% 12% 15% 5% 3 3 2 3 4 12%	4109
	11th to 20th	Night	15% 21% 10% 19% 5% 4 7% 4 3 3 10%	4120
	21st to end	Night	26% 20% 9% 15% 6% 3 3 2 2 3 12%	4532
February	1st to 10th	Night	20% 18% 5% 13% 7% 4 3 3 4 5% 19%	2470
	11th to 20th	Night	16% 16% 6% 13% 7% 6% 4 3 4 4 20%	2360
	21st to end	Night	20% 14% 5% 13% 7% 4 4 3 4 4 23%	1884
March	1st to 10th	Night	22% 15% 4 7% 4 3 3 3 3 4 32%	3487
	11th to 20th	Night	16% 13% 6% 8% 4 4 4 4 4 5% 32%	3480
	21st to end	Night	19% 13% 5% 9% 4 3 3 3 4 5% 32%	3817
April	1st to 10th	Night	17% 15% 4 7% 5% 4 5% 4 5% 6% 30%	2044
	11th to 20th	Night	16% 11% 2 7% 5% 5% 5% 3 6% 6% 33%	1740
	21st to end	Night	15% 12% 4 6% 5% 4 5% 4 6% 6% 35%	1710
May	1st to 10th	Night	25% 10% 3 6% 4 4 4 3 5% 6% 29%	2813
	11th to 20th	Night	17% 10% 3 6% 4 4 4 3 7% 8% 36%	2812
	21st to end	Night	13% 5% 1 4 3 4 4 4 7% 11% 44%	2962
June	1st to 10th	Night	11% 7% 2 6% 4 5% 6% 5% 6% 6% 41%	1520
	11th to 20th	Night	10% 5% 2 7% 5% 5% 5% 4 6% 9% 41%	1520
	21st to end	Night	11% 5% 2 6% 5% 4 4 4 8% 11% 39%	1520
July	1st to 10th	Night	10% 7% 2 6% 5% 4 3 3 5% 9% 46%	2799
	11th to 20th	Night	10% 5% 2 5% 4 3 4 4 6% 8% 48%	2840
	21st to end	Night	9% 6% 3 6% 5% 5% 5% 4 6% 8% 45%	3087
August	1st to 10th	Night	10% 8% 3 7% 5% 5% 5% 4 6% 8% 39%	2825
	11th to 20th	Night	17% 8% 2 6% 4 4 3 3 4 7% 42%	2785
	21st to end	Night	8% 5% 3 7% 5% 5% 6% 4 6% 8% 43%	3178
September	1st to 10th	Night	13% 6% 2 5% 4 5% 4 4 5% 7% 45%	1985
	11th to 20th	Night	10% 5% 2 5% 4 4 4 4 6% 7% 50%	2024
	21st to end	Night	15% 8% 2 8% 5% 4 4 4 5% 6% 40%	1980
October	1st to 10th	Night	14% 7% 2 6% 4 4 4 4 5% 7% 42%	2106
	11th to 20th	Night	21% 8% 3 8% 4 5% 4 4 5% 6% 32%	2160
	21st to end	Night	26% 11% 3 6% 4 4 4 3 5% 6% 28%	2376
November	1st to 10th	Night	16% 11% 3 7% 5% 4 4 2 6% 6% 37%	2401
	11th to 20th	Night	17% 18% 5% 8% 5% 5% 3 3 5% 6% 25%	2514
	21st to end	Night	20% 19% 5% 8% 5% 5% 4 4 5% 5% 21%	2660
December	1st to 10th	Night	20% 21% 7% 10% 5% 5% 3 3 4 5% 17%	2660
	11th to 20th	Night	17% 20% 8% 12% 5% 4 4 3 4 5% 19%	3285
	21st to end	Night	25% 24% 8% 10% 5% 4 4 3 3 4 10%	4779

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	76% 3 10% 9% 2	2837
	11th to 20th	Day	78% 3 8% 9% 2	2840
	21st to end	Day	86% 2 4 5% 2	3124
February	1st to 10th	Day	71% 2 8% 13% 6%	1710
	11th to 20th	Day	70% 4 7% 13% 6%	1714
	21st to end	Day	66% 4 10% 13% 7% 2	1570
March	1st to 10th	Day	61% 3 10% 21% 4	3365
	11th to 20th	Day	56% 5% 14% 19% 6% 1	3480
	21st to end	Day	60% 4 8% 17% 11% 1	3815
April	1st to 10th	Day	54% 4 11% 17% 13% 1	2135
	11th to 20th	Day	53% 4 10% 18% 13% 2	2404
	21st to end	Day	54% 3 10% 20% 10% 2	2470
May	1st to 10th	Day	54% 4 9% 23% 9% 1	4120
	11th to 20th	Day	50% 4 12% 23% 10% 1	4085
	21st to end	Day	42% 4 13% 20% 16% 5%	4603
June	1st to 10th	Day	45% 5% 10% 26% 13% 1	2660
	11th to 20th	Day	42% 5% 15% 22% 15% 1	2660
	21st to end	Day	40% 4 13% 25% 16% 2	2660
July	1st to 10th	Day	41% 4 12% 24% 16% 3	4090
	11th to 20th	Day	36% 5% 13% 27% 18% 1	4051
	21st to end	Day	41% 6% 13% 19% 19% 2	4324
August	1st to 10th	Day	44% 5% 14% 24% 11%	4091
	11th to 20th	Day	43% 6% 11% 29% 10% 1	4083
	21st to end	Day	38% 6% 14% 29% 11% 2	4446
September	1st to 10th	Day	41% 5% 13% 22% 16% 3	2192
	11th to 20th	Day	40% 4 14% 25% 16% 1	2014
	21st to end	Day	47% 4 9% 25% 15% 1	1980
October	1st to 10th	Day	45% 5% 11% 23% 14% 1	1854
	11th to 20th	Day	54% 5% 11% 20% 9% 1	1800
	21st to end	Day	61% 4 11% 14% 9% 1	1980
November	1st to 10th	Day	49% 5% 10% 21% 14% 1	1672
	11th to 20th	Day	60% 4 9% 17% 7% 3	1663
	21st to end	Day	69% 4 8% 13% 6%	1520
December	1st to 10th	Day	75% 4 8% 11% 3	1520
	11th to 20th	Day	74% 4 7% 12% 3	1906
	21st to end	Day	82% 2 8% 6% 1	2872
January	1st to 10th	Night	77% 3 6% 9% 4	4109
	11th to 20th	Night	82% 3 6% 7% 2	4120
	21st to end	Night	81% 2 6% 9% 2	4532
February	1st to 10th	Night	69% 4 8% 13% 6%	2470
	11th to 20th	Night	67% 4 7% 16% 6%	2362
	21st to end	Night	66% 4 8% 14% 7% 1	1884
March	1st to 10th	Night	56% 3 11% 21% 8%	3487
	11th to 20th	Night	52% 7% 16% 15% 9% 1	3480
	21st to end	Night	53% 7% 7% 21% 10% 1	3817
April	1st to 10th	Night	54% 4 10% 17% 12% 2	2044
	11th to 20th	Night	51% 4 12% 17% 15% 2	1740
	21st to end	Night	48% 5% 11% 20% 14% 3	1710
May	1st to 10th	Night	56% 3 10% 20% 10% 2	2840
	11th to 20th	Night	45% 5% 12% 23% 12% 2	2813
	21st to end	Night	33% 5% 16% 26% 18% 3	2969
June	1st to 10th	Night	42% 5% 10% 26% 15% 3	1520
	11th to 20th	Night	39% 4 15% 21% 19% 2	1520
	21st to end	Night	37% 7% 12% 26% 17% 2	1520
July	1st to 10th	Night	37% 4 11% 25% 18% 5%	2754
	11th to 20th	Night	33% 4 12% 29% 19% 2	2786
	21st to end	Night	37% 5% 13% 19% 24% 2	2988
August	1st to 10th	Night	42% 6% 12% 25% 13% 1	2814
	11th to 20th	Night	43% 5% 10% 29% 12% 1	2812
	21st to end	Night	37% 6% 11% 29% 15% 2	3178
September	1st to 10th	Night	38% 5% 11% 26% 17% 3	1985
	11th to 20th	Night	32% 5% 13% 28% 20% 1	2024
	21st to end	Night	45% 4 10% 21% 19% 1	1980
October	1st to 10th	Night	40% 5% 13% 22% 19% 1	2106
	11th to 20th	Night	52% 4 9% 22% 11% 1	2160
	21st to end	Night	58% 4 10% 18% 9% 2	2376
November	1st to 10th	Night	47% 4 11% 22% 13% 3	2401
	11th to 20th	Night	61% 3 9% 17% 8% 2	2514
	21st to end	Night	66% 4 10% 15% 5%	2660
December	1st to 10th	Night	71% 3 9% 11% 5%	2660
	11th to 20th	Night	69% 4 10% 14% 3	3288
	21st to end	Night	79% 3 9% 7% 1	4779

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	35% 24% 28% 10% 3	270
	11th to 20th	Day	37% 26% 28% 6% 1 1	270
	21st to end	Day	34% 29% 28% 7% 2	297
February	1st to 10th	Day	37% 21% 35% 7% 1	270
	11th to 20th	Day	36% 30% 28% 5%	270
	21st to end	Day	43% 27% 25% 4	225
March	1st to 10th	Day	33% 20% 31% 13% 3	412
	11th to 20th	Day	33% 19% 33% 12% 3 1	460
	21st to end	Day	37% 20% 26% 13% 3	506
April	1st to 10th	Day	28% 22% 30% 15% 5%	460
	11th to 20th	Day	34% 17% 27% 13% 7% 2	452
	21st to end	Day	33% 15% 33% 14% 4 1	460
May	1st to 10th	Day	29% 16% 31% 18% 4 2	463
	11th to 20th	Day	26% 9% 32% 23% 7% 3	487
	21st to end	Day	17% 8% 32% 26% 13% 4	529
June	1st to 10th	Day	20% 10% 36% 22% 10% 3	490
	11th to 20th	Day	18% 10% 29% 28% 12% 3	490
	21st to end	Day	17% 11% 33% 23% 11% 4	490
July	1st to 10th	Day	14% 7% 25% 30% 18% 8%	485
	11th to 20th	Day	15% 6% 28% 28% 17% 6%	484
	21st to end	Day	12% 8% 28% 29% 16% 7%	532
August	1st to 10th	Day	14% 6% 26% 29% 19% 6%	486
	11th to 20th	Day	17% 7% 26% 28% 15% 8%	479
	21st to end	Day	13% 5% 27% 28% 18% 8%	539
September	1st to 10th	Day	19% 7% 24% 26% 18% 6%	490
	11th to 20th	Day	13% 4 22% 30% 21% 9%	463
	21st to end	Day	23% 10% 27% 23% 12% 5%	450
October	1st to 10th	Day	18% 11% 29% 22% 17% 3	450
	11th to 20th	Day	28% 18% 32% 15% 6% 1	450
	21st to end	Day	37% 16% 29% 14% 3	495
November	1st to 10th	Day	25% 21% 29% 16% 7% 1	270
	11th to 20th	Day	39% 17% 25% 13% 4 1	248
	21st to end	Day	34% 19% 39% 7% 1	180
December	1st to 10th	Day	34% 22% 28% 12% 3 2	180
	11th to 20th	Day	32% 29% 30% 8% 1	180
	21st to end	Day	38% 24% 30% 7%	227
January	1st to 10th	Night	31% 24% 30% 12% 3	760
	11th to 20th	Night	34% 23% 28% 13% 2	760
	21st to end	Night	30% 21% 31% 16% 2	836
February	1st to 10th	Night	31% 22% 29% 16% 2	760
	11th to 20th	Night	29% 24% 30% 17% 1	743
	21st to end	Night	31% 23% 31% 14% 1	628
March	1st to 10th	Night	26% 22% 29% 19% 4	760
	11th to 20th	Night	26% 19% 30% 18% 6% 1	760
	21st to end	Night	28% 16% 31% 20% 6% 1	836
April	1st to 10th	Night	27% 16% 30% 21% 6%	760
	11th to 20th	Night	23% 16% 34% 18% 8% 1	616
	21st to end	Night	23% 12% 34% 25% 6%	570
May	1st to 10th	Night	24% 10% 29% 28% 8% 1	570
	11th to 20th	Night	21% 7% 28% 33% 9% 2	561
	21st to end	Night	13% 3 29% 36% 18% 1	551
June	1st to 10th	Night	12% 6% 31% 39% 12% 1	380
	11th to 20th	Night	13% 5% 29% 39% 14% 1	380
	21st to end	Night	12% 6% 28% 37% 16%	380
July	1st to 10th	Night	11% 2 17% 40% 27% 4	527
	11th to 20th	Night	11% 3 22% 37% 23% 5%	552
	21st to end	Night	12% 2 18% 42% 24% 2	624
August	1st to 10th	Night	10% 3 17% 42% 25% 3	567
	11th to 20th	Night	15% 3 14% 37% 27% 3	564
	21st to end	Night	11% 3 21% 33% 28% 4	655
September	1st to 10th	Night	17% 6% 17% 34% 24% 3	760
	11th to 20th	Night	14% 2 19% 34% 27% 4	736
	21st to end	Night	19% 7% 26% 28% 16% 4	720
October	1st to 10th	Night	19% 9% 28% 26% 16% 3	720
	11th to 20th	Night	28% 13% 28% 24% 7% 1	720
	21st to end	Night	34% 13% 31% 18% 4	792
November	1st to 10th	Night	23% 14% 28% 25% 9% 1	740
	11th to 20th	Night	30% 20% 28% 15% 6% 1	760
	21st to end	Night	34% 18% 29% 13% 5%	760
December	1st to 10th	Night	35% 21% 28% 12% 4	760
	11th to 20th	Night	30% 24% 29% 14% 3	760
	21st to end	Night	36% 19% 31% 13% 1	836

Page generated at 2024-09-11 10:00:06. Version ac07

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