Sideroad 10D
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sideroad 10D clear sky chart from 2005-11-06 to 2024-04-25.

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% 12% 6% 10% 7% 4 5% 4 5% 6% 27%	83369
	Night	14% 13% 6% 11% 8% 4 5% 4 5% 6% 25%	85727
Transparency	Day	57% 6% 10% 17% 9% 1	83076
	Night	60% 6% 10% 15% 8% 1	85555
Seeing	Day	19% 17% 29% 22% 10% 3	14244
	Night	20% 16% 30% 24% 9% 1	23554

By Month

Percentage Cloud Cover NE (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% 11% 18% 14% 4 4 4 3 4 8%	2208
	11th to 20th	Day	8% 16% 11% 23% 15% 7% 5% 3 4 3 5%	2754
	21st to end	Day	15% 19% 10% 17% 10% 4 6% 4 3 3 8%	3124
February	1st to 10th	Day	12% 15% 8% 17% 13% 5% 5% 5% 4 4 11%	1710
	11th to 20th	Day	11% 13% 8% 18% 13% 5% 5% 5% 4 5% 14%	1663
	21st to end	Day	12% 18% 8% 13% 10% 5% 5% 4 4 4 17%	1498
March	1st to 10th	Day	13% 14% 6% 11% 8% 3 4 4 4 5% 26%	3385
	11th to 20th	Day	9% 15% 13% 14% 7% 3 4 4 4 4 23%	3480
	21st to end	Day	13% 14% 7% 9% 6% 3 5% 4 4 6% 28%	3815
April	1st to 10th	Day	16% 15% 6% 9% 6% 3 4 4 4 6% 25%	2204
	11th to 20th	Day	17% 13% 3 7% 5% 3 3 4 4 5% 35%	2406
	21st to end	Day	19% 12% 5% 6% 5% 3 3 4 5% 5% 32%	2394
May	1st to 10th	Day	17% 10% 4 7% 5% 3 4 4 6% 7% 34%	2340
	11th to 20th	Day	17% 10% 3 6% 6% 3 4 4 5% 6% 37%	2424
	21st to end	Day	13% 8% 3 5% 5% 3 5% 4 6% 8% 40%	2725
June	1st to 10th	Day	16% 7% 3 5% 4 3 5% 5% 6% 9% 36%	2563
	11th to 20th	Day	13% 7% 3 4 5% 3 5% 6% 7% 9% 39%	2700
	21st to end	Day	16% 6% 3 5% 6% 3 5% 6% 5% 8% 38%	2700
July	1st to 10th	Day	12% 5% 2 5% 5% 3 5% 5% 6% 9% 43%	2700
	11th to 20th	Day	12% 6% 3 6% 6% 3 5% 5% 7% 8% 38%	2601
	21st to end	Day	12% 6% 3 6% 6% 4 5% 6% 6% 9% 36%	2547
August	1st to 10th	Day	12% 6% 3 6% 5% 3 6% 5% 6% 9% 38%	2327
	11th to 20th	Day	12% 6% 2 6% 7% 4 5% 6% 6% 9% 38%	2303
	21st to end	Day	15% 6% 3 5% 6% 4 5% 5% 6% 9% 35%	2531
September	1st to 10th	Day	16% 8% 2 7% 6% 3 5% 4 5% 7% 37%	2160
	11th to 20th	Day	16% 6% 2 5% 5% 4 4 5% 6% 8% 39%	1994
	21st to end	Day	17% 7% 3 8% 6% 5% 4 5% 5% 7% 33%	1980
October	1st to 10th	Day	20% 11% 3 6% 5% 3 5% 4 5% 7% 31%	1801
	11th to 20th	Day	21% 15% 4 9% 7% 5% 5% 4 5% 6% 20%	1800
	21st to end	Day	27% 19% 4 8% 5% 3 5% 3 5% 4 16%	1950
November	1st to 10th	Day	14% 20% 5% 8% 6% 3 5% 4 4 6% 24%	1601
	11th to 20th	Day	14% 18% 6% 11% 8% 4 6% 4 5% 7% 17%	1520
	21st to end	Day	16% 19% 8% 13% 8% 4 5% 5% 4 5% 12%	1520
December	1st to 10th	Day	12% 22% 13% 18% 7% 4 4 4 3 4 8%	1520
	11th to 20th	Day	15% 18% 10% 17% 10% 3 5% 4 3 4 11%	1906
	21st to end	Day	20% 21% 9% 16% 8% 4 4 4 3 4 8%	2515
January	1st to 10th	Night	12% 20% 11% 18% 13% 4 4 5% 4 3 7%	4748
	11th to 20th	Night	11% 12% 10% 22% 15% 6% 5% 4 4 3 6%	4200
	21st to end	Night	14% 16% 9% 17% 13% 5% 5% 5% 4 3 8%	4532
February	1st to 10th	Night	10% 16% 10% 16% 11% 6% 6% 5% 4 4 13%	2470
	11th to 20th	Night	10% 13% 9% 15% 11% 5% 6% 5% 4 5% 16%	2403
	21st to end	Night	12% 13% 6% 13% 10% 5% 6% 5% 4 5% 20%	1953
March	1st to 10th	Night	12% 14% 6% 8% 5% 3 5% 5% 4 7% 30%	3453
	11th to 20th	Night	9% 16% 7% 10% 6% 3 4 4 5% 6% 30%	3479
	21st to end	Night	11% 11% 5% 10% 7% 4 5% 5% 5% 6% 32%	3817
April	1st to 10th	Night	18% 13% 5% 8% 6% 3 4 4 5% 6% 29%	1974
	11th to 20th	Night	17% 11% 4 7% 5% 3 3 4 3 7% 37%	1739
	21st to end	Night	16% 13% 5% 8% 6% 3 4 4 4 6% 32%	1665
May	1st to 10th	Night	15% 9% 3 5% 5% 3 5% 4 6% 8% 37%	1620
	11th to 20th	Night	15% 7% 2 5% 5% 2 5% 4 5% 6% 44%	1469
	21st to end	Night	9% 5% 3 5% 4 3 5% 5% 6% 8% 47%	1550
June	1st to 10th	Night	14% 7% 3 6% 5% 3 6% 5% 5% 9% 39%	1393
	11th to 20th	Night	11% 5% 2 4 5% 4 5% 5% 6% 10% 42%	1260
	21st to end	Night	14% 6% 2 5% 4 3 4 5% 5% 8% 43%	1260
July	1st to 10th	Night	9% 5% 2 3 3 2 3 3 5% 8% 55%	1260
	11th to 20th	Night	10% 5% 2 5% 5% 3 5% 4 7% 8% 46%	1350
	21st to end	Night	8% 5% 2 5% 5% 4 5% 5% 7% 8% 47%	1771
August	1st to 10th	Night	9% 6% 2 5% 5% 3 5% 5% 7% 7% 46%	1611
	11th to 20th	Night	8% 4 2 5% 5% 4 5% 5% 6% 10% 46%	1598
	21st to end	Night	12% 6% 2 6% 6% 3 5% 5% 5% 7% 44%	1806
September	1st to 10th	Night	13% 4 3 5% 4 3 4 5% 6% 9% 45%	1800
	11th to 20th	Night	14% 6% 2 4 4 2 3 4 6% 7% 47%	1963
	21st to end	Night	18% 8% 3 6% 5% 3 5% 4 4 7% 36%	1980
October	1st to 10th	Night	20% 8% 3 6% 5% 4 5% 3 4 7% 35%	2158
	11th to 20th	Night	22% 13% 4 8% 6% 3 5% 4 5% 6% 25%	2160
	21st to end	Night	22% 19% 4 7% 7% 4 5% 4 5% 6% 19%	2402
November	1st to 10th	Night	16% 19% 5% 7% 6% 3 4 4 4 5% 26%	2475
	11th to 20th	Night	14% 17% 6% 10% 7% 4 5% 4 6% 6% 19%	2660
	21st to end	Night	16% 17% 10% 11% 8% 4 5% 4 5% 5% 15%	2660
December	1st to 10th	Night	15% 20% 11% 15% 7% 3 5% 5% 3 5% 11%	2660
	11th to 20th	Night	10% 18% 11% 17% 10% 5% 5% 5% 4 4 11%	3288
	21st to end	Night	19% 19% 10% 19% 8% 4 4 4 3 3 7%	5140

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	81% 5% 8% 5%	2209
	11th to 20th	Day	85% 6% 3 4 2	2754
	21st to end	Day	81% 4 8% 5% 2	3124
February	1st to 10th	Day	76% 6% 6% 9% 2	1710
	11th to 20th	Day	73% 5% 7% 9% 5% 1	1672
	21st to end	Day	71% 6% 7% 11% 5%	1498
March	1st to 10th	Day	62% 5% 11% 14% 9% 1	3388
	11th to 20th	Day	63% 5% 7% 17% 6% 1	3480
	21st to end	Day	55% 6% 11% 17% 9% 2	3815
April	1st to 10th	Day	61% 5% 8% 17% 8% 1	2204
	11th to 20th	Day	52% 5% 8% 20% 15% 1	2406
	21st to end	Day	54% 6% 9% 18% 12% 3	2394
May	1st to 10th	Day	49% 6% 9% 21% 13% 1	2340
	11th to 20th	Day	48% 6% 7% 23% 15% 1	2428
	21st to end	Day	42% 6% 14% 23% 14% 2	2725
June	1st to 10th	Day	44% 7% 11% 22% 15% 1	2563
	11th to 20th	Day	39% 8% 11% 24% 17% 1	2700
	21st to end	Day	43% 7% 13% 24% 13% 1	2700
July	1st to 10th	Day	37% 6% 14% 24% 17% 2	2626
	11th to 20th	Day	40% 8% 12% 28% 11% 1	2520
	21st to end	Day	44% 8% 11% 23% 13% 1	2405
August	1st to 10th	Day	41% 9% 15% 23% 11% 1	2314
	11th to 20th	Day	41% 9% 15% 24% 11%	2303
	21st to end	Day	45% 8% 12% 23% 11% 1	2531
September	1st to 10th	Day	47% 6% 11% 23% 10% 2	2160
	11th to 20th	Day	42% 5% 14% 28% 10% 1	1994
	21st to end	Day	51% 7% 11% 24% 7% 1	1980
October	1st to 10th	Day	53% 6% 11% 18% 12% 1	1801
	11th to 20th	Day	65% 6% 10% 12% 6% 1	1800
	21st to end	Day	71% 5% 9% 9% 5%	1950
November	1st to 10th	Day	62% 5% 11% 15% 6%	1601
	11th to 20th	Day	67% 7% 10% 10% 5%	1520
	21st to end	Day	74% 6% 9% 9% 1	1520
December	1st to 10th	Day	81% 6% 7% 5% 1	1520
	11th to 20th	Day	79% 5% 9% 7% 1	1906
	21st to end	Day	83% 4 6% 5% 1	2515
January	1st to 10th	Night	83% 5% 7% 5% 1	4748
	11th to 20th	Night	84% 7% 5% 3 1	4200
	21st to end	Night	81% 4 9% 4 2	4532
February	1st to 10th	Night	74% 6% 7% 10% 2	2470
	11th to 20th	Night	70% 6% 9% 12% 4	2405
	21st to end	Night	64% 8% 9% 12% 7%	1953
March	1st to 10th	Night	54% 7% 12% 19% 8% 1	3463
	11th to 20th	Night	53% 8% 11% 17% 8% 1	3480
	21st to end	Night	53% 5% 9% 22% 9% 1	3817
April	1st to 10th	Night	57% 4 7% 20% 11%	1974
	11th to 20th	Night	50% 5% 8% 20% 17% 1	1739
	21st to end	Night	54% 5% 8% 15% 15% 2	1665
May	1st to 10th	Night	45% 5% 10% 20% 17% 2	1620
	11th to 20th	Night	41% 5% 10% 24% 17% 3	1470
	21st to end	Night	33% 7% 15% 27% 14% 3	1551
June	1st to 10th	Night	43% 5% 12% 21% 18% 2	1393
	11th to 20th	Night	37% 7% 11% 26% 18% 1	1260
	21st to end	Night	40% 5% 14% 26% 14% 1	1260
July	1st to 10th	Night	28% 5% 12% 29% 23% 3	1225
	11th to 20th	Night	34% 5% 15% 30% 15% 1	1308
	21st to end	Night	33% 9% 13% 29% 15% 1	1672
August	1st to 10th	Night	34% 7% 16% 28% 14% 1	1600
	11th to 20th	Night	32% 7% 15% 29% 15% 1	1598
	21st to end	Night	40% 8% 13% 26% 12% 1	1806
September	1st to 10th	Night	35% 8% 14% 28% 13% 1	1800
	11th to 20th	Night	36% 5% 16% 28% 15% 1	1963
	21st to end	Night	47% 7% 12% 24% 9% 1	1980
October	1st to 10th	Night	50% 6% 11% 20% 13% 1	2158
	11th to 20th	Night	59% 7% 13% 16% 6%	2160
	21st to end	Night	67% 6% 9% 12% 5%	2402
November	1st to 10th	Night	60% 5% 10% 17% 7% 1	2475
	11th to 20th	Night	65% 6% 13% 12% 4 2	2660
	21st to end	Night	71% 7% 12% 8% 2	2660
December	1st to 10th	Night	77% 7% 9% 5% 2	2660
	11th to 20th	Night	77% 5% 10% 7% 1	3288
	21st to end	Night	85% 4 5% 5% 1	5140

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	17% 29% 33% 15% 5% 1	180
	11th to 20th	Day	16% 32% 36% 12% 3	263
	21st to end	Day	23% 22% 34% 19% 2	297
February	1st to 10th	Day	23% 31% 33% 10% 2	270
	11th to 20th	Day	20% 30% 39% 9% 2	270
	21st to end	Day	25% 32% 34% 9%	225
March	1st to 10th	Day	20% 23% 37% 16% 4	424
	11th to 20th	Day	19% 22% 38% 17% 4	460
	21st to end	Day	26% 16% 33% 18% 6%	506
April	1st to 10th	Day	23% 21% 34% 17% 5%	460
	11th to 20th	Day	28% 21% 24% 14% 8% 4	452
	21st to end	Day	27% 16% 29% 21% 7% 1	437
May	1st to 10th	Day	21% 16% 32% 21% 9% 2	423
	11th to 20th	Day	19% 9% 31% 24% 13% 3	447
	21st to end	Day	17% 10% 26% 27% 15% 4	485
June	1st to 10th	Day	17% 13% 28% 29% 12% 2	493
	11th to 20th	Day	15% 12% 30% 30% 11% 3	630
	21st to end	Day	17% 9% 31% 28% 11% 3	630
July	1st to 10th	Day	11% 8% 26% 33% 18% 4	621
	11th to 20th	Day	13% 9% 28% 30% 14% 7%	533
	21st to end	Day	10% 6% 31% 34% 16% 3	488
August	1st to 10th	Day	13% 6% 24% 33% 16% 8%	446
	11th to 20th	Day	14% 6% 20% 32% 20% 8%	439
	21st to end	Day	14% 11% 24% 29% 16% 5%	495
September	1st to 10th	Day	15% 14% 25% 24% 16% 6%	450
	11th to 20th	Day	14% 9% 24% 27% 18% 8%	450
	21st to end	Day	15% 15% 28% 24% 14% 4	450
October	1st to 10th	Day	24% 16% 23% 20% 13% 4	450
	11th to 20th	Day	24% 24% 32% 16% 4	450
	21st to end	Day	32% 27% 25% 13% 4	465
November	1st to 10th	Day	24% 27% 30% 14% 5%	237
	11th to 20th	Day	24% 29% 33% 11% 2 1	180
	21st to end	Day	23% 29% 38% 9% 1	180
December	1st to 10th	Day	21% 35% 32% 12% 1	180
	11th to 20th	Day	21% 37% 31% 9% 2	180
	21st to end	Day	26% 34% 32% 6% 2	198
January	1st to 10th	Night	20% 28% 33% 16% 4	950
	11th to 20th	Night	22% 24% 33% 17% 4 1	786
	21st to end	Night	15% 18% 40% 21% 5% 1	836
February	1st to 10th	Night	19% 26% 35% 19% 2	760
	11th to 20th	Night	18% 21% 36% 20% 4	743
	21st to end	Night	21% 24% 33% 18% 3	628
March	1st to 10th	Night	17% 20% 37% 20% 5%	760
	11th to 20th	Night	17% 21% 37% 19% 4 1	760
	21st to end	Night	19% 16% 31% 26% 7% 1	836
April	1st to 10th	Night	23% 17% 33% 24% 3	760
	11th to 20th	Night	21% 15% 31% 23% 9% 1	615
	21st to end	Night	22% 14% 28% 25% 11%	555
May	1st to 10th	Night	19% 8% 27% 32% 12% 2	540
	11th to 20th	Night	18% 8% 27% 34% 12% 1	408
	21st to end	Night	13% 5% 28% 38% 15%	389
June	1st to 10th	Night	17% 7% 31% 34% 10% 1	360
	11th to 20th	Night	11% 9% 23% 40% 17%	360
	21st to end	Night	17% 5% 24% 35% 18% 1	360
July	1st to 10th	Night	9% 5% 18% 46% 21% 1	350
	11th to 20th	Night	10% 5% 28% 34% 22% 1	358
	21st to end	Night	10% 4 25% 41% 18% 1	591
August	1st to 10th	Night	12% 5% 21% 36% 25% 1	537
	11th to 20th	Night	9% 5% 18% 38% 26% 4	534
	21st to end	Night	15% 7% 23% 29% 23% 2	618
September	1st to 10th	Night	14% 8% 24% 32% 17% 5%	720
	11th to 20th	Night	17% 6% 23% 34% 17% 4	720
	21st to end	Night	19% 11% 22% 29% 14% 4	720
October	1st to 10th	Night	24% 10% 29% 22% 13% 1	720
	11th to 20th	Night	27% 19% 27% 20% 6% 1	720
	21st to end	Night	33% 19% 28% 16% 3 1	792
November	1st to 10th	Night	27% 17% 31% 17% 7%	740
	11th to 20th	Night	22% 28% 29% 16% 4 1	760
	21st to end	Night	24% 24% 34% 16% 2	760
December	1st to 10th	Night	26% 25% 33% 12% 3	760
	11th to 20th	Night	21% 27% 36% 13% 2 1	760
	21st to end	Night	27% 25% 34% 13% 1	988

Page generated at 2024-04-22 09:25:42. Version ac07

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