Antigonish
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Antigonish clear sky chart from 2005-11-06 to 2024-01-16.

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	19% 12% 5% 8% 7% 4 5% 5% 5% 6% 26%	74749
	Night	19% 11% 5% 9% 7% 4 5% 5% 5% 6% 25%	75062
Transparency	Day	58% 7% 11% 16% 7% 1	74452
	Night	58% 7% 12% 15% 7% 1	74894
Seeing	Day	25% 17% 30% 21% 6% 1	16388
	Night	25% 17% 31% 22% 5%	24061

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% 14% 9% 15% 8% 5% 6% 4 4 4 14%	1516
	11th to 20th	Day	17% 16% 8% 14% 8% 4 6% 5% 4 4 13%	1481
	21st to end	Day	13% 12% 6% 13% 11% 6% 7% 4 4 5% 20%	1701
February	1st to 10th	Day	17% 13% 6% 11% 9% 4 6% 4 5% 5% 20%	1620
	11th to 20th	Day	15% 15% 5% 9% 9% 6% 5% 4 4 5% 22%	1573
	21st to end	Day	9% 15% 7% 8% 8% 4 6% 6% 5% 6% 25%	1429
March	1st to 10th	Day	14% 17% 6% 9% 6% 4 5% 5% 6% 5% 24%	1854
	11th to 20th	Day	10% 13% 9% 11% 9% 5% 5% 4 5% 5% 24%	1980
	21st to end	Day	17% 17% 8% 10% 8% 2 3 3 3 4 25%	2250
April	1st to 10th	Day	19% 13% 6% 9% 6% 3 5% 4 5% 5% 25%	2160
	11th to 20th	Day	21% 13% 4 6% 6% 2 4 3 4 6% 31%	2134
	21st to end	Day	23% 15% 4 7% 5% 3 3 5% 5% 6% 25%	2310
May	1st to 10th	Day	25% 13% 4 6% 5% 3 4 4 5% 6% 25%	2519
	11th to 20th	Day	19% 10% 3 7% 6% 4 5% 5% 5% 6% 29%	2478
	21st to end	Day	20% 10% 4 6% 5% 3 4 5% 5% 7% 31%	2724
June	1st to 10th	Day	28% 10% 3 5% 5% 3 5% 4 5% 8% 23%	2520
	11th to 20th	Day	23% 9% 3 7% 5% 3 4 4 5% 6% 32%	2520
	21st to end	Day	23% 10% 4 7% 7% 3 4 5% 5% 6% 25%	2520
July	1st to 10th	Day	15% 6% 3 6% 6% 3 5% 6% 6% 8% 35%	2520
	11th to 20th	Day	14% 6% 3 6% 6% 3 6% 6% 7% 10% 33%	2520
	21st to end	Day	18% 9% 4 7% 6% 4 6% 6% 6% 7% 28%	2745
August	1st to 10th	Day	17% 7% 3 5% 5% 4 5% 5% 6% 8% 35%	2409
	11th to 20th	Day	17% 9% 4 7% 6% 3 5% 5% 6% 7% 33%	2304
	21st to end	Day	15% 6% 3 5% 6% 3 5% 5% 6% 8% 37%	2407
September	1st to 10th	Day	17% 6% 4 7% 6% 3 4 5% 5% 7% 36%	2160
	11th to 20th	Day	20% 9% 3 5% 4 3 4 4 6% 7% 34%	2160
	21st to end	Day	19% 7% 3 5% 5% 4 5% 5% 5% 7% 35%	1898
October	1st to 10th	Day	19% 8% 3 8% 6% 3 5% 5% 5% 7% 31%	1800
	11th to 20th	Day	21% 10% 4 9% 6% 4 4 5% 5% 8% 25%	1800
	21st to end	Day	21% 14% 5% 9% 8% 3 5% 4 4 7% 21%	1884
November	1st to 10th	Day	21% 13% 5% 8% 7% 3 4 5% 5% 5% 22%	1604
	11th to 20th	Day	18% 18% 7% 10% 8% 3 4 5% 4 6% 18%	1520
	21st to end	Day	16% 18% 7% 11% 8% 4 5% 5% 5% 4 16%	1520
December	1st to 10th	Day	20% 17% 8% 12% 9% 4 6% 4 4 4 11%	1520
	11th to 20th	Day	28% 17% 7% 13% 8% 4 5% 4 4 4 8%	1906
	21st to end	Day	21% 14% 12% 12% 7% 4 4 3 4 4 16%	2783
January	1st to 10th	Night	16% 15% 8% 12% 9% 5% 6% 4 4 5% 15%	2649
	11th to 20th	Night	16% 14% 7% 13% 9% 5% 6% 4 5% 5% 16%	2601
	21st to end	Night	13% 11% 8% 12% 8% 5% 7% 5% 5% 6% 22%	2650
February	1st to 10th	Night	18% 11% 5% 11% 9% 4 6% 4 5% 5% 22%	2340
	11th to 20th	Night	15% 13% 6% 9% 10% 6% 7% 7% 4 5% 18%	2273
	21st to end	Night	10% 14% 7% 12% 8% 4 5% 4 5% 5% 26%	1826
March	1st to 10th	Night	15% 15% 7% 11% 7% 4 4 4 4 5% 23%	2090
	11th to 20th	Night	15% 11% 6% 10% 8% 3 5% 5% 5% 5% 27%	1979
	21st to end	Night	19% 12% 6% 9% 7% 3 4 4 4 5% 27%	2106
April	1st to 10th	Night	21% 14% 5% 6% 6% 4 5% 5% 4 6% 24%	1800
	11th to 20th	Night	20% 11% 4 7% 6% 3 4 4 5% 6% 31%	1776
	21st to end	Night	23% 13% 4 6% 6% 3 6% 4 4 5% 27%	1648
May	1st to 10th	Night	27% 12% 4 6% 5% 3 3 4 4 5% 28%	1440
	11th to 20th	Night	20% 11% 3 7% 4 3 4 5% 5% 6% 32%	1416
	21st to end	Night	15% 11% 4 7% 5% 3 5% 5% 6% 9% 31%	1550
June	1st to 10th	Night	26% 8% 4 7% 7% 3 5% 3 5% 6% 25%	1440
	11th to 20th	Night	23% 8% 2 5% 5% 3 4 4 4 8% 34%	1440
	21st to end	Night	22% 8% 3 6% 7% 3 5% 5% 5% 8% 29%	1440
July	1st to 10th	Night	15% 6% 3 7% 5% 3 5% 5% 8% 9% 33%	1440
	11th to 20th	Night	14% 6% 2 5% 5% 4 6% 7% 7% 11% 33%	1440
	21st to end	Night	15% 8% 3 6% 6% 4 6% 6% 7% 8% 31%	1573
August	1st to 10th	Night	14% 6% 3 6% 6% 4 5% 5% 6% 8% 38%	1526
	11th to 20th	Night	16% 7% 4 5% 6% 4 5% 6% 6% 9% 32%	1596
	21st to end	Night	13% 6% 2 6% 5% 3 5% 5% 6% 10% 38%	1948
September	1st to 10th	Night	14% 6% 3 6% 5% 3 5% 5% 6% 8% 37%	1800
	11th to 20th	Night	18% 8% 2 5% 5% 2 3 4 6% 7% 38%	1800
	21st to end	Night	19% 7% 2 6% 5% 3 4 4 4 8% 37%	2059
October	1st to 10th	Night	19% 8% 2 6% 6% 3 4 4 6% 6% 35%	2160
	11th to 20th	Night	20% 8% 3 7% 6% 3 4 4 5% 8% 31%	2160
	21st to end	Night	25% 12% 4 8% 7% 3 5% 4 4 5% 23%	2470
November	1st to 10th	Night	19% 12% 4 9% 7% 3 5% 5% 5% 6% 24%	2469
	11th to 20th	Night	19% 14% 5% 10% 7% 4 5% 5% 5% 6% 19%	2660
	21st to end	Night	20% 14% 5% 9% 8% 4 5% 6% 5% 6% 18%	2660
December	1st to 10th	Night	22% 15% 7% 14% 8% 4 5% 4 4 4 13%	2660
	11th to 20th	Night	27% 15% 5% 12% 9% 5% 4 3 3 4 13%	3293
	21st to end	Night	27% 15% 6% 12% 7% 3 3 3 3 3 17%	4884

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	71% 6% 12% 8% 3	1517
	11th to 20th	Day	71% 7% 12% 7% 4	1481
	21st to end	Day	64% 6% 10% 11% 8% 1	1701
February	1st to 10th	Day	66% 5% 11% 11% 6%	1620
	11th to 20th	Day	64% 7% 12% 12% 6%	1581
	21st to end	Day	58% 5% 11% 14% 9% 2	1429
March	1st to 10th	Day	62% 5% 9% 14% 10% 1	1858
	11th to 20th	Day	61% 5% 12% 14% 7% 1	1980
	21st to end	Day	66% 4 7% 14% 8% 2	2250
April	1st to 10th	Day	62% 6% 8% 12% 10% 3	2160
	11th to 20th	Day	56% 4 9% 17% 12% 1	2134
	21st to end	Day	61% 7% 10% 14% 7% 1	2310
May	1st to 10th	Day	61% 6% 9% 15% 8% 1	2519
	11th to 20th	Day	53% 9% 9% 19% 10% 1	2482
	21st to end	Day	53% 7% 11% 20% 8%	2724
June	1st to 10th	Day	61% 7% 11% 17% 4 1	2520
	11th to 20th	Day	52% 8% 10% 19% 10%	2520
	21st to end	Day	60% 9% 8% 13% 9% 1	2520
July	1st to 10th	Day	45% 10% 15% 20% 9%	2450
	11th to 20th	Day	46% 9% 14% 24% 7% 1	2444
	21st to end	Day	55% 10% 11% 18% 6% 1	2592
August	1st to 10th	Day	46% 9% 13% 24% 7%	2395
	11th to 20th	Day	50% 9% 13% 20% 8%	2304
	21st to end	Day	44% 7% 13% 25% 10%	2407
September	1st to 10th	Day	46% 8% 13% 22% 10% 1	2160
	11th to 20th	Day	49% 7% 11% 21% 12% 1	2160
	21st to end	Day	47% 7% 11% 23% 12%	1898
October	1st to 10th	Day	51% 6% 12% 20% 9% 1	1800
	11th to 20th	Day	56% 7% 15% 16% 6%	1800
	21st to end	Day	64% 7% 11% 11% 6% 1	1884
November	1st to 10th	Day	61% 7% 12% 14% 5%	1604
	11th to 20th	Day	66% 6% 13% 9% 5%	1520
	21st to end	Day	65% 8% 15% 8% 4	1520
December	1st to 10th	Day	74% 8% 9% 7% 2	1520
	11th to 20th	Day	77% 6% 9% 5% 2 1	1905
	21st to end	Day	69% 7% 15% 6% 2 1	2783
January	1st to 10th	Night	69% 6% 13% 9% 3	2649
	11th to 20th	Night	69% 7% 12% 8% 3	2601
	21st to end	Night	62% 7% 13% 13% 6%	2650
February	1st to 10th	Night	64% 6% 11% 11% 7% 1	2340
	11th to 20th	Night	66% 6% 11% 11% 5% 1	2276
	21st to end	Night	59% 4 10% 16% 8% 1	1826
March	1st to 10th	Night	64% 4 9% 14% 9%	2099
	11th to 20th	Night	58% 5% 11% 16% 8% 2	1980
	21st to end	Night	60% 5% 9% 15% 9% 2	2106
April	1st to 10th	Night	61% 7% 10% 12% 10% 2	1800
	11th to 20th	Night	54% 6% 9% 18% 11% 2	1776
	21st to end	Night	58% 5% 10% 15% 10% 1	1648
May	1st to 10th	Night	60% 5% 8% 18% 9% 1	1440
	11th to 20th	Night	51% 6% 10% 22% 10% 1	1417
	21st to end	Night	50% 8% 14% 20% 7% 1	1551
June	1st to 10th	Night	59% 8% 9% 18% 6%	1440
	11th to 20th	Night	51% 7% 11% 17% 13% 1	1440
	21st to end	Night	54% 11% 10% 15% 9% 1	1440
July	1st to 10th	Night	44% 10% 17% 20% 8%	1401
	11th to 20th	Night	43% 12% 13% 22% 10% 1	1392
	21st to end	Night	49% 11% 16% 18% 6%	1486
August	1st to 10th	Night	43% 9% 17% 25% 5%	1515
	11th to 20th	Night	46% 11% 15% 21% 6%	1596
	21st to end	Night	39% 12% 17% 23% 8%	1948
September	1st to 10th	Night	42% 8% 14% 26% 10%	1800
	11th to 20th	Night	43% 7% 13% 25% 11%	1800
	21st to end	Night	46% 7% 12% 24% 10% 1	2059
October	1st to 10th	Night	46% 8% 15% 20% 11%	2160
	11th to 20th	Night	51% 7% 15% 24% 4	2160
	21st to end	Night	62% 7% 10% 13% 8%	2470
November	1st to 10th	Night	58% 9% 13% 14% 6%	2469
	11th to 20th	Night	62% 8% 14% 10% 5%	2660
	21st to end	Night	63% 9% 15% 10% 3	2660
December	1st to 10th	Night	72% 7% 11% 8% 3	2660
	11th to 20th	Night	75% 4 10% 7% 3 1	3295
	21st to end	Night	71% 5% 13% 9% 2	4884

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% 24% 33% 13% 2	370
	11th to 20th	Day	27% 25% 28% 14% 5%	356
	21st to end	Day	21% 25% 36% 16% 2	374
February	1st to 10th	Day	29% 25% 31% 13% 1 1	340
	11th to 20th	Day	26% 31% 26% 15% 2	336
	21st to end	Day	20% 22% 36% 17% 5%	280
March	1st to 10th	Day	22% 23% 36% 17% 2	366
	11th to 20th	Day	20% 25% 34% 15% 5% 1	420
	21st to end	Day	29% 23% 27% 17% 4	462
April	1st to 10th	Day	30% 26% 29% 13% 3	420
	11th to 20th	Day	29% 23% 32% 12% 4	412
	21st to end	Day	28% 18% 30% 19% 5% 1	420
May	1st to 10th	Day	33% 16% 29% 16% 3 2	602
	11th to 20th	Day	22% 13% 34% 23% 8% 1	624
	21st to end	Day	25% 14% 34% 21% 5% 1	680
June	1st to 10th	Day	33% 11% 30% 19% 7% 1	630
	11th to 20th	Day	22% 13% 33% 25% 5% 1	630
	21st to end	Day	24% 11% 29% 26% 10% 1	630
July	1st to 10th	Day	18% 8% 33% 31% 8% 1	620
	11th to 20th	Day	16% 8% 33% 31% 11% 1	618
	21st to end	Day	21% 9% 27% 31% 11% 1	685
August	1st to 10th	Day	16% 6% 29% 34% 12% 3	528
	11th to 20th	Day	19% 9% 31% 26% 12% 3	439
	21st to end	Day	17% 11% 30% 27% 13% 2	495
September	1st to 10th	Day	17% 13% 33% 28% 8% 2	450
	11th to 20th	Day	26% 14% 27% 23% 7% 1	450
	21st to end	Day	23% 15% 30% 19% 9% 3	383
October	1st to 10th	Day	24% 12% 29% 27% 6% 3	360
	11th to 20th	Day	25% 20% 28% 16% 9% 2	360
	21st to end	Day	28% 20% 30% 16% 6%	396
November	1st to 10th	Day	25% 23% 28% 19% 3 1	365
	11th to 20th	Day	31% 26% 25% 14% 4 1	370
	21st to end	Day	31% 25% 27% 14% 3 1	370
December	1st to 10th	Day	31% 25% 27% 14% 2	370
	11th to 20th	Day	36% 25% 28% 11% 1	370
	21st to end	Day	23% 29% 31% 13% 2 1	407
January	1st to 10th	Night	27% 24% 33% 14% 2	850
	11th to 20th	Night	25% 24% 32% 16% 3	829
	21st to end	Night	22% 25% 32% 17% 3	826
February	1st to 10th	Night	28% 18% 33% 19% 2	720
	11th to 20th	Night	25% 28% 31% 13% 2	703
	21st to end	Night	20% 19% 35% 20% 5%	592
March	1st to 10th	Night	23% 19% 34% 20% 3	720
	11th to 20th	Night	22% 18% 30% 22% 7% 1	720
	21st to end	Night	27% 16% 31% 22% 4	720
April	1st to 10th	Night	29% 19% 30% 20% 3	540
	11th to 20th	Night	25% 18% 32% 20% 4 1	534
	21st to end	Night	30% 15% 28% 22% 5%	540
May	1st to 10th	Night	32% 13% 27% 20% 7% 1	540
	11th to 20th	Night	26% 11% 32% 24% 6% 1	532
	21st to end	Night	22% 13% 39% 21% 4	583
June	1st to 10th	Night	29% 9% 33% 24% 6%	540
	11th to 20th	Night	27% 9% 30% 29% 4 1	540
	21st to end	Night	24% 11% 29% 29% 7%	540
July	1st to 10th	Night	18% 6% 34% 34% 8% 1	526
	11th to 20th	Night	16% 5% 34% 35% 9% 1	522
	21st to end	Night	18% 7% 28% 36% 10%	590
August	1st to 10th	Night	15% 6% 28% 38% 13%	538
	11th to 20th	Night	20% 6% 27% 33% 13% 1	532
	21st to end	Night	15% 9% 25% 40% 11%	594
September	1st to 10th	Night	16% 8% 33% 33% 9% 1	540
	11th to 20th	Night	22% 13% 26% 27% 12%	540
	21st to end	Night	23% 12% 32% 26% 5% 1	666
October	1st to 10th	Night	22% 12% 33% 24% 9% 1	720
	11th to 20th	Night	22% 16% 33% 22% 7%	720
	21st to end	Night	30% 21% 28% 16% 4	839
November	1st to 10th	Night	27% 22% 29% 17% 4 1	830
	11th to 20th	Night	26% 26% 27% 15% 5%	850
	21st to end	Night	30% 23% 29% 16% 3	850
December	1st to 10th	Night	31% 23% 30% 12% 4	850
	11th to 20th	Night	33% 25% 29% 10% 2	850
	21st to end	Night	29% 26% 29% 13% 3 1	935

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