Blind River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blind River clear sky chart from 2005-11-06 to 2024-02-05.

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% 10% 4 6% 6% 3 5% 5% 5% 7% 35%	77839
	Night	16% 12% 4 7% 6% 3 5% 5% 5% 6% 31%	81051
Transparency	Day	32% 39% 10% 12% 6% 1	77536
	Night	37% 37% 9% 11% 5% 1	80889
Seeing	Day	19% 10% 28% 28% 13% 3	14333
	Night	21% 8% 28% 30% 12% 1	23853

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	16% 20% 7% 10% 5% 3 4 5% 5% 6% 19%	2276
	11th to 20th	Day	11% 16% 6% 12% 11% 4 7% 6% 4 5% 18%	2530
	21st to end	Day	15% 24% 8% 12% 7% 4 5% 4 4 4 14%	2810
February	1st to 10th	Day	10% 12% 5% 10% 8% 6% 5% 4 6% 7% 27%	1656
	11th to 20th	Day	12% 13% 4 7% 7% 4 5% 5% 6% 6% 31%	1596
	21st to end	Day	11% 14% 6% 9% 8% 3 5% 4 5% 6% 29%	1480
March	1st to 10th	Day	13% 11% 3 5% 4 2 5% 5% 5% 7% 39%	1833
	11th to 20th	Day	11% 10% 4 7% 5% 3 4 4 4 6% 40%	1980
	21st to end	Day	16% 7% 3 6% 5% 3 4 5% 5% 7% 39%	2178
April	1st to 10th	Day	18% 10% 4 6% 5% 3 5% 5% 5% 7% 32%	2140
	11th to 20th	Day	19% 8% 3 6% 5% 3 4 5% 5% 7% 36%	2312
	21st to end	Day	19% 9% 3 6% 5% 3 3 4 5% 7% 36%	2340
May	1st to 10th	Day	16% 6% 3 6% 5% 3 5% 5% 5% 8% 38%	2340
	11th to 20th	Day	15% 6% 2 5% 5% 3 5% 5% 5% 8% 41%	2354
	21st to end	Day	13% 5% 2 4 5% 3 5% 5% 5% 8% 44%	2906
June	1st to 10th	Day	13% 5% 2 5% 5% 3 5% 5% 6% 9% 43%	2700
	11th to 20th	Day	12% 6% 3 5% 4 2 5% 6% 6% 9% 41%	2700
	21st to end	Day	14% 6% 2 5% 5% 3 5% 5% 6% 8% 41%	2700
July	1st to 10th	Day	9% 4 2 3 4 3 5% 5% 6% 9% 51%	2700
	11th to 20th	Day	11% 5% 2 4 5% 2 4 5% 6% 8% 47%	2617
	21st to end	Day	11% 5% 2 4 4 2 4 6% 6% 8% 48%	2740
August	1st to 10th	Day	11% 5% 2 5% 4 4 5% 5% 7% 7% 46%	2327
	11th to 20th	Day	11% 5% 2 5% 6% 3 4 5% 6% 9% 45%	2303
	21st to end	Day	12% 5% 3 5% 5% 3 4 5% 6% 7% 46%	2574
September	1st to 10th	Day	12% 6% 3 5% 6% 3 4 4 5% 7% 44%	2121
	11th to 20th	Day	13% 5% 3 5% 4 2 5% 4 5% 9% 44%	1980
	21st to end	Day	18% 7% 3 6% 5% 3 3 4 5% 8% 38%	1980
October	1st to 10th	Day	20% 6% 2 6% 6% 3 5% 4 5% 6% 37%	1886
	11th to 20th	Day	22% 9% 4 6% 5% 4 5% 6% 5% 7% 26%	1800
	21st to end	Day	22% 11% 3 7% 6% 4 5% 5% 6% 6% 24%	1782
November	1st to 10th	Day	20% 10% 4 7% 6% 3 5% 5% 5% 9% 27%	1672
	11th to 20th	Day	15% 15% 7% 9% 9% 3 5% 4 5% 6% 24%	1531
	21st to end	Day	22% 20% 6% 7% 7% 3 4 4 5% 6% 18%	1520
December	1st to 10th	Day	14% 19% 8% 9% 8% 3 5% 5% 4 6% 20%	1373
	11th to 20th	Day	18% 17% 6% 10% 7% 3 5% 4 5% 6% 20%	1671
	21st to end	Day	29% 22% 4 7% 5% 3 3 3 3 5% 15%	2431
January	1st to 10th	Night	16% 17% 6% 11% 7% 3 5% 4 5% 6% 21%	4679
	11th to 20th	Night	13% 14% 6% 13% 10% 4 5% 5% 5% 6% 19%	4440
	21st to end	Night	16% 19% 7% 10% 8% 4 5% 4 4 4 18%	4854
February	1st to 10th	Night	12% 13% 5% 8% 9% 5% 5% 5% 5% 6% 26%	2399
	11th to 20th	Night	13% 13% 5% 9% 8% 4 5% 5% 5% 6% 27%	2246
	21st to end	Night	13% 15% 6% 9% 7% 3 7% 5% 4 5% 27%	1776
March	1st to 10th	Night	12% 8% 4 6% 5% 3 6% 4 6% 7% 39%	2114
	11th to 20th	Night	14% 10% 4 5% 4 4 5% 5% 4 7% 37%	1979
	21st to end	Night	15% 9% 3 6% 5% 3 5% 5% 6% 5% 39%	2178
April	1st to 10th	Night	20% 9% 3 7% 5% 3 4 4 5% 7% 33%	1833
	11th to 20th	Night	19% 8% 2 5% 4 2 4 3 5% 7% 40%	1597
	21st to end	Night	20% 7% 4 6% 6% 3 4 4 5% 6% 35%	1620
May	1st to 10th	Night	13% 7% 4 8% 6% 3 4 6% 6% 7% 35%	1620
	11th to 20th	Night	15% 8% 3 5% 6% 3 5% 5% 5% 6% 38%	1539
	21st to end	Night	14% 4 2 5% 5% 3 4 4 5% 8% 46%	1366
June	1st to 10th	Night	13% 4 3 6% 4 3 5% 5% 6% 9% 43%	1260
	11th to 20th	Night	11% 6% 3 6% 6% 3 5% 5% 5% 7% 42%	1260
	21st to end	Night	13% 6% 3 6% 6% 4 5% 4 5% 7% 42%	1260
July	1st to 10th	Night	9% 5% 3 3 4 2 4 4 5% 8% 52%	1260
	11th to 20th	Night	7% 4 3 5% 6% 3 4 5% 6% 6% 49%	1340
	21st to end	Night	10% 4 2 5% 4 3 5% 5% 6% 9% 48%	1576
August	1st to 10th	Night	8% 5% 2 4 6% 3 5% 6% 4 8% 49%	1611
	11th to 20th	Night	10% 5% 3 4 4 4 4 6% 6% 8% 46%	1598
	21st to end	Night	12% 6% 3 6% 5% 2 5% 3 5% 7% 46%	1782
September	1st to 10th	Night	13% 5% 2 5% 5% 4 5% 5% 5% 7% 45%	1818
	11th to 20th	Night	13% 4 2 5% 4 2 3 4 4 7% 52%	1980
	21st to end	Night	19% 7% 3 6% 5% 3 4 4 5% 8% 38%	1980
October	1st to 10th	Night	19% 9% 3 6% 5% 2 3 4 5% 6% 38%	2074
	11th to 20th	Night	24% 9% 3 6% 6% 3 5% 5% 5% 5% 28%	2160
	21st to end	Night	26% 10% 3 7% 6% 3 4 3 5% 6% 26%	2573
November	1st to 10th	Night	18% 10% 4 6% 5% 3 5% 5% 5% 7% 33%	2406
	11th to 20th	Night	19% 14% 4 8% 7% 3 5% 5% 6% 7% 23%	2647
	21st to end	Night	21% 17% 6% 7% 5% 3 4 4 5% 6% 21%	2660
December	1st to 10th	Night	17% 18% 6% 9% 7% 3 4 5% 4 6% 20%	2804
	11th to 20th	Night	19% 16% 5% 7% 6% 3 5% 5% 5% 6% 22%	3526
	21st to end	Night	28% 22% 6% 8% 5% 2 3 3 4 4 16%	5236

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	51% 32% 9% 7% 1	2277
	11th to 20th	Day	52% 32% 9% 5% 2	2530
	21st to end	Day	61% 26% 6% 4 3	2810
February	1st to 10th	Day	38% 38% 10% 9% 4	1656
	11th to 20th	Day	33% 41% 10% 10% 5% 1	1605
	21st to end	Day	36% 40% 8% 10% 5% 1	1480
March	1st to 10th	Day	29% 38% 11% 11% 9% 2	1836
	11th to 20th	Day	29% 38% 9% 15% 6% 2	1980
	21st to end	Day	30% 40% 9% 13% 6% 2	2178
April	1st to 10th	Day	32% 39% 10% 12% 7% 1	2140
	11th to 20th	Day	31% 38% 8% 16% 7%	2312
	21st to end	Day	31% 38% 7% 10% 11% 4	2340
May	1st to 10th	Day	27% 38% 9% 15% 9% 2	2340
	11th to 20th	Day	26% 38% 8% 14% 12% 1	2358
	21st to end	Day	24% 40% 9% 14% 11% 2	2906
June	1st to 10th	Day	25% 40% 10% 16% 9% 1	2700
	11th to 20th	Day	23% 40% 10% 16% 10% 1	2700
	21st to end	Day	27% 39% 11% 14% 7% 1	2700
July	1st to 10th	Day	18% 41% 12% 17% 10% 1	2626
	11th to 20th	Day	21% 41% 9% 18% 10% 1	2536
	21st to end	Day	21% 42% 12% 18% 7%	2588
August	1st to 10th	Day	25% 40% 13% 14% 6% 1	2314
	11th to 20th	Day	20% 41% 14% 16% 9% 1	2303
	21st to end	Day	22% 40% 11% 19% 7% 1	2574
September	1st to 10th	Day	24% 39% 11% 18% 7% 1	2121
	11th to 20th	Day	24% 40% 14% 17% 5%	1980
	21st to end	Day	29% 40% 11% 14% 6%	1980
October	1st to 10th	Day	30% 38% 10% 16% 5%	1886
	11th to 20th	Day	38% 42% 9% 9% 2	1800
	21st to end	Day	38% 41% 11% 6% 3	1782
November	1st to 10th	Day	32% 44% 10% 11% 3	1672
	11th to 20th	Day	36% 43% 10% 8% 4	1531
	21st to end	Day	43% 42% 8% 5% 1	1520
December	1st to 10th	Day	43% 43% 8% 5% 1	1373
	11th to 20th	Day	46% 38% 8% 8% 1	1671
	21st to end	Day	58% 28% 6% 4 4	2431
January	1st to 10th	Night	48% 31% 10% 6% 4 1	4679
	11th to 20th	Night	51% 31% 10% 6% 2	4440
	21st to end	Night	56% 26% 6% 8% 3	4854
February	1st to 10th	Night	39% 38% 8% 11% 4 1	2399
	11th to 20th	Night	39% 40% 10% 8% 3	2248
	21st to end	Night	40% 37% 9% 10% 4	1776
March	1st to 10th	Night	28% 38% 11% 13% 9% 1	2124
	11th to 20th	Night	31% 38% 10% 14% 7% 1	1980
	21st to end	Night	29% 39% 9% 11% 9% 2	2178
April	1st to 10th	Night	31% 39% 7% 13% 9% 1	1833
	11th to 20th	Night	29% 37% 6% 17% 10%	1597
	21st to end	Night	32% 37% 6% 11% 11% 3	1620
May	1st to 10th	Night	28% 39% 8% 13% 9% 2	1620
	11th to 20th	Night	29% 38% 6% 16% 9% 2	1540
	21st to end	Night	22% 39% 8% 15% 12% 4	1367
June	1st to 10th	Night	26% 39% 9% 15% 10% 1	1260
	11th to 20th	Night	24% 39% 8% 16% 12% 1	1260
	21st to end	Night	28% 39% 11% 15% 7% 1	1260
July	1st to 10th	Night	19% 40% 11% 18% 12% 1	1225
	11th to 20th	Night	21% 41% 9% 18% 10% 1	1298
	21st to end	Night	24% 41% 10% 17% 8%	1488
August	1st to 10th	Night	23% 41% 11% 18% 6% 1	1600
	11th to 20th	Night	21% 39% 12% 18% 9% 1	1598
	21st to end	Night	24% 39% 10% 17% 8% 1	1782
September	1st to 10th	Night	24% 39% 10% 17% 8% 2	1818
	11th to 20th	Night	23% 39% 12% 22% 4	1980
	21st to end	Night	31% 39% 11% 14% 5%	1980
October	1st to 10th	Night	29% 39% 10% 15% 7%	2074
	11th to 20th	Night	38% 39% 9% 11% 2	2160
	21st to end	Night	39% 41% 9% 9% 2	2573
November	1st to 10th	Night	30% 45% 9% 12% 4	2406
	11th to 20th	Night	38% 43% 8% 7% 4	2647
	21st to end	Night	40% 44% 9% 6% 1	2660
December	1st to 10th	Night	41% 44% 7% 6% 1	2804
	11th to 20th	Night	42% 38% 8% 6% 3 2	3525
	21st to end	Night	58% 27% 8% 5% 2	5236

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	27% 13% 28% 23% 7% 4	200
	11th to 20th	Day	19% 9% 31% 27% 11% 2	270
	21st to end	Day	22% 12% 28% 27% 10% 1	297
February	1st to 10th	Day	21% 17% 31% 21% 7% 2	252
	11th to 20th	Day	17% 18% 36% 20% 9% 1	240
	21st to end	Day	24% 22% 31% 21% 2	198
March	1st to 10th	Day	20% 17% 33% 20% 8% 2	276
	11th to 20th	Day	18% 12% 29% 31% 8% 1	420
	21st to end	Day	26% 10% 28% 26% 8% 2	462
April	1st to 10th	Day	22% 12% 27% 28% 10% 1	420
	11th to 20th	Day	25% 12% 27% 20% 12% 3	412
	21st to end	Day	23% 12% 29% 22% 12% 3	420
May	1st to 10th	Day	22% 9% 28% 27% 11% 4	423
	11th to 20th	Day	17% 7% 28% 28% 15% 6%	447
	21st to end	Day	16% 8% 29% 31% 13% 3	666
June	1st to 10th	Day	14% 7% 33% 30% 13% 2	630
	11th to 20th	Day	17% 9% 28% 32% 13% 2	630
	21st to end	Day	16% 6% 29% 32% 13% 4	630
July	1st to 10th	Day	10% 6% 29% 35% 18% 2	621
	11th to 20th	Day	12% 6% 29% 31% 16% 6%	618
	21st to end	Day	11% 5% 29% 33% 16% 6%	681
August	1st to 10th	Day	15% 4 18% 32% 25% 6%	446
	11th to 20th	Day	12% 5% 16% 32% 22% 12%	439
	21st to end	Day	14% 8% 23% 28% 20% 6%	495
September	1st to 10th	Day	17% 9% 19% 30% 19% 7%	450
	11th to 20th	Day	16% 6% 23% 31% 19% 5%	450
	21st to end	Day	21% 11% 21% 29% 14% 4	450
October	1st to 10th	Day	25% 12% 20% 23% 17% 3	450
	11th to 20th	Day	24% 15% 29% 25% 6% 1	450
	21st to end	Day	27% 14% 31% 24% 3 1	297
November	1st to 10th	Day	28% 13% 27% 25% 6%	270
	11th to 20th	Day	25% 21% 28% 22% 4 1	185
	21st to end	Day	27% 16% 34% 16% 8% 1	180
December	1st to 10th	Day	25% 11% 32% 22% 8% 3	180
	11th to 20th	Day	26% 12% 41% 16% 5% 1	180
	21st to end	Day	35% 13% 34% 12% 6% 1	198
January	1st to 10th	Night	23% 8% 34% 27% 8% 1	950
	11th to 20th	Night	23% 11% 29% 26% 10% 1	950
	21st to end	Night	23% 7% 27% 32% 10% 1	1028
February	1st to 10th	Night	18% 10% 37% 27% 7%	739
	11th to 20th	Night	18% 9% 32% 31% 9%	703
	21st to end	Night	21% 11% 33% 29% 6% 1	592
March	1st to 10th	Night	17% 8% 33% 33% 8% 1	720
	11th to 20th	Night	20% 9% 32% 29% 10% 1	720
	21st to end	Night	18% 7% 30% 34% 11% 1	792
April	1st to 10th	Night	24% 8% 29% 31% 8%	604
	11th to 20th	Night	22% 7% 29% 29% 11% 2	533
	21st to end	Night	22% 6% 29% 30% 12% 1	540
May	1st to 10th	Night	16% 5% 28% 38% 11% 2	540
	11th to 20th	Night	17% 5% 24% 40% 12% 1	478
	21st to end	Night	15% 4 27% 38% 16%	389
June	1st to 10th	Night	13% 4 29% 40% 13%	360
	11th to 20th	Night	12% 6% 22% 44% 15% 1	360
	21st to end	Night	16% 3 21% 37% 23% 1	360
July	1st to 10th	Night	10% 3 19% 51% 17%	350
	11th to 20th	Night	8% 3 21% 43% 23% 3	428
	21st to end	Night	13% 2 22% 39% 22% 2	591
August	1st to 10th	Night	11% 2 20% 39% 27% 1	537
	11th to 20th	Night	12% 2 18% 35% 28% 4	534
	21st to end	Night	15% 4 21% 35% 23% 3	594
September	1st to 10th	Night	16% 5% 21% 33% 20% 5%	630
	11th to 20th	Night	13% 6% 23% 33% 20% 5%	720
	21st to end	Night	21% 5% 23% 32% 15% 3	720
October	1st to 10th	Night	24% 6% 24% 30% 14% 2	720
	11th to 20th	Night	28% 11% 24% 28% 8%	720
	21st to end	Night	29% 10% 30% 24% 6% 1	792
November	1st to 10th	Night	24% 11% 29% 27% 10%	740
	11th to 20th	Night	26% 12% 31% 24% 8%	760
	21st to end	Night	30% 11% 32% 21% 5% 1	760
December	1st to 10th	Night	26% 14% 32% 21% 7%	904
	11th to 20th	Night	26% 13% 36% 18% 6% 1	950
	21st to end	Night	32% 10% 30% 20% 7%	1045

Page generated at 2024-02-02 05:20:33. Version ac07

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