Tignish
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tignish clear sky chart from 2005-11-06 to 2025-07-06.

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	17% 11% 4 9% 5% 5% 4 3 5% 6% 31%	120054
	Night	18% 13% 4 11% 6% 5% 4 3 5% 6% 27%	118859
Transparency	Day	54% 5% 12% 20% 8% 1	123617
	Night	59% 5% 11% 17% 8% 1	123447
Seeing	Day	22% 9% 26% 28% 13% 2	17794
	Night	25% 10% 27% 26% 10% 1	25250

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	15% 24% 8% 17% 8% 4 4 3 4 4 9%	3157
	11th to 20th	Day	12% 16% 11% 16% 8% 6% 5% 3 3 3 17%	3293
	21st to end	Day	6% 9% 5% 10% 8% 8% 7% 5% 5% 7% 30%	4396
February	1st to 10th	Day	15% 12% 3 9% 5% 6% 4 3 5% 5% 33%	1800
	11th to 20th	Day	14% 14% 4 8% 6% 5% 4 4 5% 6% 31%	1753
	21st to end	Day	11% 12% 4 7% 6% 5% 5% 4 5% 6% 36%	1485
March	1st to 10th	Day	17% 14% 5% 11% 5% 7% 4 3 4 5% 25%	4856
	11th to 20th	Day	14% 13% 5% 11% 6% 6% 5% 3 5% 7% 25%	4980
	21st to end	Day	24% 14% 4 8% 5% 4 4 3 4 6% 23%	5482
April	1st to 10th	Day	19% 11% 3 8% 4 4 4 3 5% 6% 32%	2400
	11th to 20th	Day	19% 9% 3 6% 4 3 4 3 6% 8% 36%	2497
	21st to end	Day	21% 11% 4 8% 3 4 4 3 5% 6% 32%	2600
May	1st to 10th	Day	23% 11% 4 7% 5% 4 4 3 4 6% 29%	6201
	11th to 20th	Day	19% 10% 2 6% 4 4 4 3 5% 6% 36%	6318
	21st to end	Day	19% 8% 2 7% 4 4 4 3 5% 8% 36%	6948
June	1st to 10th	Day	23% 10% 3 7% 4 4 4 3 6% 6% 29%	2968
	11th to 20th	Day	17% 8% 3 7% 5% 4 5% 4 6% 6% 36%	3000
	21st to end	Day	22% 8% 3 6% 5% 4 4 4 5% 7% 32%	3000
July	1st to 10th	Day	11% 7% 3 8% 5% 5% 5% 5% 6% 8% 37%	4835
	11th to 20th	Day	13% 7% 2 7% 4 4 5% 4 7% 8% 39%	4696
	21st to end	Day	12% 7% 3 6% 4 4 4 3 6% 8% 44%	4815
August	1st to 10th	Day	14% 8% 3 7% 5% 5% 5% 5% 6% 7% 35%	4121
	11th to 20th	Day	13% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	4045
	21st to end	Day	15% 5% 1 5% 4 4 4 3 5% 7% 47%	4410
September	1st to 10th	Day	16% 6% 3 4 3 4 4 4 6% 8% 43%	2280
	11th to 20th	Day	19% 7% 2 5% 3 4 4 3 4 6% 44%	2215
	21st to end	Day	18% 7% 2 5% 4 4 4 3 5% 7% 42%	2025
October	1st to 10th	Day	19% 8% 2 7% 4 3 4 4 4 7% 38%	1900
	11th to 20th	Day	19% 12% 4 7% 5% 4 4 3 4 8% 29%	1900
	21st to end	Day	21% 15% 3 8% 5% 4 4 3 5% 7% 25%	2030
November	1st to 10th	Day	19% 18% 5% 7% 5% 4 4 3 5% 6% 25%	1565
	11th to 20th	Day	19% 20% 6% 11% 6% 5% 3 3 4 6% 16%	1600
	21st to end	Day	20% 18% 8% 15% 6% 4 3 3 5% 5% 15%	1600
December	1st to 10th	Day	18% 15% 9% 20% 7% 5% 3 2 3 3 16%	2610
	11th to 20th	Day	18% 16% 6% 18% 8% 5% 3 2 3 2 21%	2797
	21st to end	Day	16% 15% 9% 20% 7% 5% 3 2 3 4 16%	3476
January	1st to 10th	Night	16% 21% 7% 19% 7% 4 3 2 3 4 14%	6808
	11th to 20th	Night	15% 18% 8% 15% 7% 5% 3 3 4 4 18%	6608
	21st to end	Night	7% 12% 4 11% 9% 8% 6% 4 6% 7% 26%	6559
February	1st to 10th	Night	15% 13% 4 8% 6% 5% 5% 4 5% 6% 30%	2600
	11th to 20th	Night	16% 14% 5% 8% 5% 5% 5% 4 4 5% 29%	2533
	21st to end	Night	12% 14% 3 8% 6% 4 5% 3 5% 6% 33%	2145
March	1st to 10th	Night	21% 13% 4 10% 6% 6% 4 3 4 4 25%	4967
	11th to 20th	Night	20% 16% 4 10% 5% 5% 4 3 4 5% 24%	4979
	21st to end	Night	27% 13% 4 10% 4 4 4 3 4 5% 22%	5449
April	1st to 10th	Night	22% 13% 3 8% 5% 4 4 3 4 6% 28%	2000
	11th to 20th	Night	22% 11% 3 7% 3 4 3 3 5% 6% 33%	1849
	21st to end	Night	22% 12% 4 7% 4 4 4 2 4 5% 32%	1800
May	1st to 10th	Night	27% 11% 3 7% 5% 5% 3 3 4 5% 26%	3752
	11th to 20th	Night	20% 7% 3 7% 5% 4 4 4 5% 6% 36%	3596
	21st to end	Night	18% 8% 3 7% 5% 5% 4 4 5% 7% 33%	3948
June	1st to 10th	Night	24% 12% 3 6% 5% 3 4 4 5% 6% 28%	1449
	11th to 20th	Night	18% 7% 3 6% 6% 5% 4 4 6% 7% 36%	1400
	21st to end	Night	21% 10% 3 8% 5% 5% 4 4 5% 7% 28%	1400
July	1st to 10th	Night	12% 9% 3 9% 7% 5% 5% 4 6% 7% 34%	2245
	11th to 20th	Night	14% 8% 3 7% 7% 6% 5% 4 6% 8% 32%	2241
	21st to end	Night	12% 6% 3 6% 4 4 4 5% 6% 8% 42%	2750
August	1st to 10th	Night	16% 8% 3 9% 6% 6% 7% 5% 6% 6% 29%	2794
	11th to 20th	Night	10% 7% 3 8% 5% 6% 4 4 7% 8% 38%	2782
	21st to end	Night	13% 5% 2 6% 5% 5% 4 4 5% 7% 44%	3245
September	1st to 10th	Night	16% 7% 3 6% 4 4 3 3 4 8% 43%	1900
	11th to 20th	Night	17% 7% 2 6% 3 3 4 3 4 7% 44%	1962
	21st to end	Night	17% 7% 2 7% 3 4 4 3 5% 6% 43%	2154
October	1st to 10th	Night	20% 7% 2 6% 4 4 4 4 6% 5% 37%	2280
	11th to 20th	Night	19% 12% 3 9% 5% 4 4 3 4 7% 31%	2280
	21st to end	Night	25% 13% 4 9% 5% 4 4 3 4 6% 25%	2562
November	1st to 10th	Night	21% 15% 4 8% 5% 3 3 3 4 6% 27%	2733
	11th to 20th	Night	21% 17% 5% 11% 5% 4 4 3 5% 6% 19%	2800
	21st to end	Night	24% 18% 6% 13% 4 4 3 2 5% 4 16%	2800
December	1st to 10th	Night	16% 14% 7% 18% 7% 5% 4 3 4 5% 17%	4580
	11th to 20th	Night	16% 16% 6% 20% 6% 4 3 2 3 4 21%	5407
	21st to end	Night	22% 15% 6% 17% 6% 5% 3 3 3 4 17%	7502

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	80% 5% 8% 5% 2	3158
	11th to 20th	Day	74% 4 6% 10% 5% 1	3320
	21st to end	Day	55% 5% 13% 17% 9% 1	4396
February	1st to 10th	Day	54% 5% 12% 19% 10% 1	1800
	11th to 20th	Day	55% 5% 11% 20% 9% 1	1761
	21st to end	Day	49% 4 11% 21% 13% 2	1485
March	1st to 10th	Day	62% 4 8% 17% 8% 1	4860
	11th to 20th	Day	59% 6% 14% 15% 6% 2	4980
	21st to end	Day	64% 3 6% 16% 9% 1	5482
April	1st to 10th	Day	52% 5% 10% 17% 14% 2	2400
	11th to 20th	Day	47% 5% 11% 22% 13% 1	2497
	21st to end	Day	52% 6% 10% 17% 13% 3	2600
May	1st to 10th	Day	57% 5% 10% 19% 10% 1	6213
	11th to 20th	Day	49% 4 14% 26% 6%	6322
	21st to end	Day	47% 6% 11% 25% 11%	6948
June	1st to 10th	Day	55% 6% 11% 21% 7%	2968
	11th to 20th	Day	47% 6% 13% 23% 10% 1	3000
	21st to end	Day	52% 7% 13% 18% 9% 1	3000
July	1st to 10th	Day	45% 5% 21% 19% 10%	4760
	11th to 20th	Day	43% 5% 18% 26% 8%	4615
	21st to end	Day	39% 7% 22% 24% 8%	4662
August	1st to 10th	Day	48% 6% 15% 24% 7%	4107
	11th to 20th	Day	42% 6% 15% 25% 12%	4084
	21st to end	Day	37% 5% 16% 29% 12% 1	4410
September	1st to 10th	Day	38% 7% 16% 27% 12%	2280
	11th to 20th	Day	43% 5% 15% 25% 12% 1	2215
	21st to end	Day	42% 6% 12% 27% 12%	2025
October	1st to 10th	Day	48% 3 14% 27% 8%	3160
	11th to 20th	Day	55% 3 11% 24% 6%	3140
	21st to end	Day	53% 4 18% 17% 7%	3322
November	1st to 10th	Day	61% 4 11% 18% 5% 1	1565
	11th to 20th	Day	71% 4 12% 8% 5%	1600
	21st to end	Day	73% 6% 12% 6% 2	1600
December	1st to 10th	Day	77% 3 7% 12% 2	2610
	11th to 20th	Day	74% 3 8% 8% 8%	2796
	21st to end	Day	76% 3 8% 10% 3	3476
January	1st to 10th	Night	76% 3 10% 9% 2	6808
	11th to 20th	Night	71% 4 9% 11% 5%	6656
	21st to end	Night	59% 8% 10% 16% 7% 1	6559
February	1st to 10th	Night	54% 5% 10% 16% 12% 2	2600
	11th to 20th	Night	57% 5% 9% 17% 11% 1	2536
	21st to end	Night	52% 4 9% 20% 13% 2	2145
March	1st to 10th	Night	63% 4 6% 14% 12% 1	4976
	11th to 20th	Night	62% 5% 10% 13% 8% 1	4980
	21st to end	Night	66% 3 5% 15% 10% 1	5449
April	1st to 10th	Night	57% 4 9% 15% 13% 2	2000
	11th to 20th	Night	52% 4 8% 23% 10% 2	1849
	21st to end	Night	56% 5% 8% 16% 13% 2	1800
May	1st to 10th	Night	61% 4 6% 16% 12% 1	3757
	11th to 20th	Night	49% 6% 11% 23% 10% 1	3597
	21st to end	Night	49% 6% 14% 22% 8%	3949
June	1st to 10th	Night	55% 6% 12% 19% 8%	1449
	11th to 20th	Night	46% 6% 12% 25% 10% 1	1400
	21st to end	Night	56% 6% 13% 16% 8% 1	1400
July	1st to 10th	Night	49% 4 16% 21% 10%	2210
	11th to 20th	Night	49% 5% 16% 24% 6%	2199
	21st to end	Night	39% 7% 24% 20% 10%	2663
August	1st to 10th	Night	54% 7% 14% 20% 6%	2783
	11th to 20th	Night	43% 5% 18% 23% 10% 1	2809
	21st to end	Night	40% 5% 16% 26% 13% 1	3244
September	1st to 10th	Night	41% 6% 12% 29% 11%	1900
	11th to 20th	Night	42% 5% 13% 29% 11%	1962
	21st to end	Night	42% 6% 12% 28% 12% 1	2154
October	1st to 10th	Night	53% 3 13% 24% 7%	3800
	11th to 20th	Night	53% 3 10% 26% 8%	3779
	21st to end	Night	57% 4 12% 18% 8%	4210
November	1st to 10th	Night	61% 5% 12% 16% 6% 1	2733
	11th to 20th	Night	68% 6% 10% 12% 4	2800
	21st to end	Night	72% 6% 10% 9% 3	2800
December	1st to 10th	Night	73% 3 10% 12% 2	4580
	11th to 20th	Night	71% 3 7% 14% 4 1	5409
	21st to end	Night	74% 3 10% 10% 3	7502

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	30% 18% 27% 23% 3	200
	11th to 20th	Day	26% 17% 28% 19% 6% 2	269
	21st to end	Day	15% 10% 42% 26% 7%	440
February	1st to 10th	Day	24% 14% 33% 23% 5% 2	400
	11th to 20th	Day	20% 17% 38% 19% 5% 1	396
	21st to end	Day	18% 9% 34% 28% 9% 2	331
March	1st to 10th	Day	20% 11% 36% 24% 8% 1	483
	11th to 20th	Day	15% 10% 35% 26% 12% 1	500
	21st to end	Day	26% 12% 27% 24% 9% 1	550
April	1st to 10th	Day	26% 11% 32% 22% 8% 1	500
	11th to 20th	Day	22% 10% 30% 28% 9% 2	492
	21st to end	Day	24% 10% 25% 27% 13% 2	500
May	1st to 10th	Day	29% 5% 27% 25% 11% 3	637
	11th to 20th	Day	22% 5% 24% 30% 15% 4	724
	21st to end	Day	22% 6% 26% 31% 13% 1	790
June	1st to 10th	Day	27% 5% 24% 30% 12% 3	730
	11th to 20th	Day	20% 4 21% 35% 17% 3	730
	21st to end	Day	25% 3 19% 33% 16% 3	730
July	1st to 10th	Day	17% 2 23% 33% 22% 3	695
	11th to 20th	Day	14% 4 17% 37% 23% 4	668
	21st to end	Day	17% 3 16% 38% 21% 4	740
August	1st to 10th	Day	13% 3 18% 36% 24% 6%	502
	11th to 20th	Day	16% 6% 14% 32% 26% 6%	479
	21st to end	Day	18% 5% 19% 31% 22% 6%	539
September	1st to 10th	Day	15% 4 26% 37% 15% 3	490
	11th to 20th	Day	22% 8% 22% 27% 17% 4	490
	21st to end	Day	21% 7% 27% 26% 17% 2	455
October	1st to 10th	Day	22% 10% 19% 30% 16% 3	390
	11th to 20th	Day	25% 11% 28% 24% 11% 1	390
	21st to end	Day	28% 13% 31% 21% 6% 1	429
November	1st to 10th	Day	26% 13% 35% 21% 4 1	395
	11th to 20th	Day	34% 15% 28% 18% 4 1	400
	21st to end	Day	33% 15% 30% 20% 3	400
December	1st to 10th	Day	29% 13% 37% 17% 3 1	400
	11th to 20th	Day	28% 24% 30% 15% 4	310
	21st to end	Day	19% 22% 33% 20% 6%	220
January	1st to 10th	Night	27% 14% 33% 20% 6%	900
	11th to 20th	Night	26% 14% 32% 20% 8%	900
	21st to end	Night	18% 14% 37% 22% 8% 1	895
February	1st to 10th	Night	23% 12% 35% 22% 7% 1	800
	11th to 20th	Night	24% 13% 36% 21% 4 1	783
	21st to end	Night	19% 10% 30% 29% 10% 1	660
March	1st to 10th	Night	24% 10% 34% 28% 5%	800
	11th to 20th	Night	21% 10% 31% 26% 10% 2	800
	21st to end	Night	26% 11% 28% 24% 10% 1	875
April	1st to 10th	Night	28% 10% 28% 26% 8%	600
	11th to 20th	Night	25% 7% 29% 26% 11% 2	594
	21st to end	Night	27% 8% 26% 28% 12% 1	600
May	1st to 10th	Night	30% 4 24% 28% 11% 4	600
	11th to 20th	Night	22% 3 24% 31% 16% 4	592
	21st to end	Night	19% 5% 30% 36% 10% 1	649
June	1st to 10th	Night	30% 4 20% 34% 12% 1	449
	11th to 20th	Night	19% 3 20% 36% 20% 2	400
	21st to end	Night	25% 3 17% 40% 14% 3	400
July	1st to 10th	Night	18% 3 21% 40% 16% 3	380
	11th to 20th	Night	14% 3 22% 40% 20% 1	386
	21st to end	Night	18% 3 18% 41% 18% 2	623
August	1st to 10th	Night	18% 2 19% 41% 19% 1	568
	11th to 20th	Night	20% 3 17% 36% 23% 2	562
	21st to end	Night	15% 4 18% 38% 22% 4	627
September	1st to 10th	Night	20% 6% 27% 34% 12% 2	570
	11th to 20th	Night	21% 8% 21% 33% 16% 1	632
	21st to end	Night	21% 7% 27% 32% 13% 1	760
October	1st to 10th	Night	25% 7% 27% 28% 12% 1	760
	11th to 20th	Night	25% 11% 28% 24% 11% 1	760
	21st to end	Night	34% 14% 28% 19% 5%	855
November	1st to 10th	Night	31% 16% 27% 21% 4 1	880
	11th to 20th	Night	30% 17% 28% 17% 6% 2	900
	21st to end	Night	34% 15% 27% 20% 4	900
December	1st to 10th	Night	32% 13% 33% 17% 4	900
	11th to 20th	Night	29% 22% 31% 15% 4	900
	21st to end	Night	31% 16% 26% 21% 4 1	990

Page generated at 2025-07-03 02:30:12. Version ac07

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