Moncton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Moncton clear sky chart from 2005-11-06 to 2025-09-04.

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	18% 11% 3 8% 5% 4 4 3 5% 6% 31%	126521
	Night	18% 11% 4 8% 5% 4 4 3 5% 6% 32%	122337
Transparency	Day	52% 6% 12% 20% 10% 1	130065
	Night	52% 5% 11% 20% 10% 1	126880
Seeing	Day	27% 20% 31% 16% 5% 1	17959
	Night	26% 17% 32% 21% 5%	25441

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	14% 20% 5% 13% 5% 4 4 3 4 4 23%	3157
	11th to 20th	Day	12% 17% 7% 12% 5% 4 4 3 4 5% 28%	3405
	21st to end	Day	9% 11% 4 10% 7% 4 4 4 5% 6% 37%	4466
February	1st to 10th	Day	16% 13% 4 10% 5% 4 4 3 5% 5% 30%	1800
	11th to 20th	Day	16% 14% 5% 9% 5% 5% 4 4 5% 5% 28%	1753
	21st to end	Day	11% 14% 4 9% 5% 4 3 5% 5% 7% 34%	1503
March	1st to 10th	Day	21% 16% 5% 12% 4 4 3 3 4 4 24%	4882
	11th to 20th	Day	17% 15% 4 9% 4 4 4 4 5% 7% 26%	4980
	21st to end	Day	25% 16% 4 8% 4 3 4 3 5% 5% 22%	5466
April	1st to 10th	Day	22% 15% 4 8% 5% 4 3 4 4 5% 25%	2367
	11th to 20th	Day	20% 14% 3 7% 4 5% 4 3 5% 7% 30%	2522
	21st to end	Day	23% 13% 3 7% 4 4 4 2 5% 7% 28%	2600
May	1st to 10th	Day	27% 16% 3 7% 4 4 4 3 4 5% 23%	6024
	11th to 20th	Day	23% 11% 3 7% 5% 4 4 3 5% 6% 31%	6318
	21st to end	Day	21% 11% 3 8% 5% 4 5% 4 6% 7% 27%	6948
June	1st to 10th	Day	27% 9% 2 7% 4 5% 5% 4 5% 6% 27%	2957
	11th to 20th	Day	21% 7% 3 6% 5% 5% 5% 4 6% 7% 31%	3000
	21st to end	Day	27% 10% 3 7% 5% 4 5% 3 5% 6% 26%	3000
July	1st to 10th	Day	17% 8% 2 8% 5% 6% 7% 5% 7% 9% 26%	6820
	11th to 20th	Day	14% 6% 2 7% 4 5% 4 4 6% 9% 40%	6710
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 8% 37%	6748
August	1st to 10th	Day	18% 8% 4 7% 6% 5% 5% 4 6% 7% 31%	4235
	11th to 20th	Day	14% 6% 2 7% 5% 5% 6% 4 6% 8% 36%	4175
	21st to end	Day	13% 5% 2 6% 3 4 4 3 6% 8% 45%	4581
September	1st to 10th	Day	15% 5% 2 5% 4 4 5% 4 5% 7% 43%	2316
	11th to 20th	Day	18% 7% 3 6% 4 3 3 3 5% 6% 42%	2166
	21st to end	Day	19% 7% 2 6% 4 4 4 2 4 6% 43%	2057
October	1st to 10th	Day	17% 8% 2 7% 3 3 4 3 5% 8% 39%	1900
	11th to 20th	Day	19% 9% 3 6% 4 4 5% 4 5% 6% 37%	1900
	21st to end	Day	19% 10% 4 7% 5% 5% 4 3 5% 6% 33%	2053
November	1st to 10th	Day	19% 9% 3 8% 5% 5% 4 4 4 5% 32%	1589
	11th to 20th	Day	20% 14% 5% 7% 4 3 5% 2 4 6% 31%	1600
	21st to end	Day	20% 14% 4 8% 6% 3 4 3 4 6% 29%	1600
December	1st to 10th	Day	18% 12% 3 7% 4 3 4 4 6% 7% 31%	2610
	11th to 20th	Day	19% 16% 3 9% 4 3 3 2 3 4 35%	2837
	21st to end	Day	16% 13% 5% 12% 5% 4 4 3 4 4 31%	3476
January	1st to 10th	Night	13% 18% 5% 11% 5% 4 4 3 4 5% 29%	6808
	11th to 20th	Night	14% 15% 6% 12% 6% 4 4 3 4 5% 27%	6491
	21st to end	Night	10% 13% 4 7% 6% 4 4 3 5% 6% 39%	6490
February	1st to 10th	Night	16% 13% 4 8% 5% 4 4 4 6% 5% 30%	2600
	11th to 20th	Night	17% 14% 4 8% 5% 5% 4 3 4 5% 29%	2533
	21st to end	Night	13% 15% 4 8% 5% 4 3 3 4 6% 34%	2125
March	1st to 10th	Night	27% 14% 4 10% 5% 4 4 2 3 4 24%	4957
	11th to 20th	Night	21% 15% 4 8% 5% 5% 4 3 5% 6% 24%	4979
	21st to end	Night	28% 12% 4 8% 4 4 4 3 4 3 26%	5466
April	1st to 10th	Night	22% 15% 5% 8% 4 4 3 3 4 4 27%	2032
	11th to 20th	Night	24% 11% 2 6% 5% 4 3 2 4 5% 33%	1825
	21st to end	Night	20% 14% 3 7% 4 5% 4 3 4 5% 30%	1800
May	1st to 10th	Night	28% 15% 3 6% 4 4 4 4 5% 5% 23%	3908
	11th to 20th	Night	22% 9% 2 6% 4 4 4 4 5% 7% 35%	3596
	21st to end	Night	19% 10% 3 7% 4 4 4 3 6% 7% 34%	3948
June	1st to 10th	Night	26% 8% 3 5% 4 3 4 4 6% 8% 29%	1459
	11th to 20th	Night	21% 7% 2 7% 5% 5% 4 3 5% 7% 35%	1400
	21st to end	Night	24% 10% 3 7% 5% 4 5% 3 5% 6% 28%	1400
July	1st to 10th	Night	17% 7% 3 8% 5% 5% 6% 4 8% 8% 28%	3160
	11th to 20th	Night	12% 7% 3 7% 5% 5% 5% 4 7% 7% 37%	3220
	21st to end	Night	15% 6% 2 7% 4 5% 4 4 6% 8% 38%	4115
August	1st to 10th	Night	17% 9% 4 8% 5% 5% 5% 4 6% 8% 30%	2915
	11th to 20th	Night	11% 7% 3 8% 5% 6% 6% 5% 6% 8% 36%	2872
	21st to end	Night	13% 5% 2 5% 3 3 4 4 5% 7% 49%	3317
September	1st to 10th	Night	16% 5% 2 6% 3 4 4 3 5% 8% 45%	1931
	11th to 20th	Night	16% 7% 3 6% 3 3 4 3 3 6% 47%	2010
	21st to end	Night	17% 6% 2 6% 4 4 4 3 5% 5% 44%	2123
October	1st to 10th	Night	18% 7% 3 6% 4 3 3 4 4 6% 40%	2280
	11th to 20th	Night	18% 8% 2 6% 4 5% 4 3 4 7% 39%	2280
	21st to end	Night	23% 9% 3 8% 4 4 3 3 4 5% 34%	2541
November	1st to 10th	Night	20% 9% 3 7% 4 4 4 4 5% 5% 35%	2707
	11th to 20th	Night	19% 13% 4 7% 6% 4 4 3 5% 6% 30%	2800
	21st to end	Night	22% 11% 4 7% 5% 4 3 3 4 5% 31%	2800
December	1st to 10th	Night	15% 10% 3 8% 5% 4 4 3 5% 6% 36%	4580
	11th to 20th	Night	20% 14% 4 7% 4 3 3 2 4 4 36%	5367
	21st to end	Night	20% 14% 5% 12% 4 3 3 2 4 5% 28%	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	65% 5% 10% 12% 8% 1	3158
	11th to 20th	Day	60% 4 10% 15% 10% 1	3432
	21st to end	Day	48% 5% 10% 16% 19% 3	4466
February	1st to 10th	Day	56% 5% 11% 16% 11% 2	1800
	11th to 20th	Day	58% 5% 10% 16% 10% 1	1761
	21st to end	Day	50% 4 11% 21% 11% 2	1503
March	1st to 10th	Day	64% 4 9% 12% 10% 2	4886
	11th to 20th	Day	57% 6% 15% 15% 6% 2	4980
	21st to end	Day	64% 3 7% 16% 8% 1	5466
April	1st to 10th	Day	60% 5% 8% 15% 10% 2	2367
	11th to 20th	Day	54% 6% 9% 19% 11% 1	2522
	21st to end	Day	56% 5% 9% 16% 11% 3	2600
May	1st to 10th	Day	63% 5% 8% 14% 9%	6035
	11th to 20th	Day	53% 7% 12% 22% 5%	6322
	21st to end	Day	52% 9% 12% 17% 9%	6948
June	1st to 10th	Day	56% 6% 12% 18% 8%	2957
	11th to 20th	Day	51% 7% 12% 20% 9% 1	3000
	21st to end	Day	58% 6% 10% 16% 9% 1	3000
July	1st to 10th	Day	52% 7% 16% 18% 7% 1	6745
	11th to 20th	Day	41% 6% 16% 28% 8% 1	6629
	21st to end	Day	42% 8% 17% 27% 6%	6554
August	1st to 10th	Day	51% 7% 12% 24% 6%	4222
	11th to 20th	Day	43% 8% 14% 23% 12%	4214
	21st to end	Day	36% 6% 15% 26% 16% 1	4581
September	1st to 10th	Day	39% 6% 16% 25% 14%	2316
	11th to 20th	Day	43% 5% 12% 25% 14% 1	2166
	21st to end	Day	43% 4 10% 27% 14% 1	2057
October	1st to 10th	Day	43% 7% 12% 29% 9%	3160
	11th to 20th	Day	44% 6% 9% 32% 9% 1	3140
	21st to end	Day	43% 5% 14% 20% 18%	3367
November	1st to 10th	Day	54% 5% 10% 20% 10% 1	1589
	11th to 20th	Day	55% 5% 12% 16% 12% 1	1600
	21st to end	Day	57% 5% 13% 16% 8%	1600
December	1st to 10th	Day	52% 5% 13% 23% 7%	2610
	11th to 20th	Day	56% 4 8% 18% 12% 2	2836
	21st to end	Day	58% 4 11% 17% 9% 1	3476
January	1st to 10th	Night	57% 5% 11% 21% 5% 1	6808
	11th to 20th	Night	59% 5% 12% 17% 7% 1	6539
	21st to end	Night	46% 4 9% 22% 16% 2	6490
February	1st to 10th	Night	55% 5% 11% 15% 12% 2	2600
	11th to 20th	Night	57% 5% 9% 16% 12% 1	2536
	21st to end	Night	52% 4 9% 19% 13% 2	2125
March	1st to 10th	Night	66% 3 5% 11% 12% 2	4966
	11th to 20th	Night	60% 5% 12% 13% 8% 1	4980
	21st to end	Night	63% 3 5% 16% 11% 1	5466
April	1st to 10th	Night	59% 6% 8% 13% 11% 3	2032
	11th to 20th	Night	53% 4 11% 20% 12% 1	1825
	21st to end	Night	56% 4 10% 15% 13% 1	1800
May	1st to 10th	Night	62% 6% 10% 13% 9% 1	3914
	11th to 20th	Night	49% 7% 13% 22% 7% 2	3597
	21st to end	Night	48% 9% 18% 17% 8%	3949
June	1st to 10th	Night	54% 6% 12% 20% 8%	1459
	11th to 20th	Night	49% 6% 11% 23% 10% 1	1400
	21st to end	Night	57% 7% 12% 14% 9% 1	1400
July	1st to 10th	Night	51% 7% 13% 20% 9%	3125
	11th to 20th	Night	44% 7% 17% 24% 9%	3178
	21st to end	Night	43% 7% 16% 23% 11%	3995
August	1st to 10th	Night	53% 8% 13% 20% 6%	2903
	11th to 20th	Night	42% 9% 16% 22% 11%	2899
	21st to end	Night	34% 6% 17% 27% 15% 1	3316
September	1st to 10th	Night	38% 7% 12% 30% 13%	1931
	11th to 20th	Night	40% 4 13% 28% 14% 1	2010
	21st to end	Night	42% 5% 11% 26% 14% 1	2123
October	1st to 10th	Night	49% 5% 11% 26% 9%	3800
	11th to 20th	Night	37% 5% 11% 33% 14%	3779
	21st to end	Night	45% 4 13% 21% 16% 1	4177
November	1st to 10th	Night	50% 7% 12% 20% 10% 1	2707
	11th to 20th	Night	55% 5% 12% 18% 10% 1	2800
	21st to end	Night	55% 5% 13% 18% 9%	2800
December	1st to 10th	Night	47% 5% 12% 26% 10%	4580
	11th to 20th	Night	53% 4 8% 20% 13% 2	5369
	21st to end	Night	61% 4 10% 16% 9% 1	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	33% 25% 31% 12%	200
	11th to 20th	Day	34% 27% 24% 12% 4	271
	21st to end	Day	20% 22% 40% 15% 3	440
February	1st to 10th	Day	26% 26% 30% 14% 4	400
	11th to 20th	Day	30% 30% 27% 10% 3 1	396
	21st to end	Day	25% 23% 34% 15% 4	341
March	1st to 10th	Day	30% 26% 31% 11% 1 1	500
	11th to 20th	Day	25% 25% 33% 12% 4 1	500
	21st to end	Day	34% 25% 27% 10% 3 1	550
April	1st to 10th	Day	38% 27% 26% 8% 2	500
	11th to 20th	Day	35% 26% 24% 12% 2	492
	21st to end	Day	32% 25% 26% 12% 4	500
May	1st to 10th	Day	36% 23% 24% 13% 3	563
	11th to 20th	Day	28% 19% 30% 17% 6% 1	724
	21st to end	Day	28% 20% 31% 16% 4	790
June	1st to 10th	Day	35% 14% 31% 15% 5%	730
	11th to 20th	Day	23% 19% 32% 19% 5% 1	730
	21st to end	Day	28% 17% 29% 21% 5% 1	730
July	1st to 10th	Day	23% 14% 36% 21% 6% 1	720
	11th to 20th	Day	17% 9% 38% 26% 8% 1	718
	21st to end	Day	20% 12% 38% 22% 7% 1	717
August	1st to 10th	Day	16% 12% 37% 27% 7% 1	526
	11th to 20th	Day	20% 11% 33% 25% 9% 2	519
	21st to end	Day	16% 17% 35% 23% 8% 2	583
September	1st to 10th	Day	14% 15% 41% 20% 9% 2	502
	11th to 20th	Day	23% 14% 31% 21% 9% 1	490
	21st to end	Day	21% 17% 34% 18% 7% 3	473
October	1st to 10th	Day	24% 16% 29% 18% 12% 1	390
	11th to 20th	Day	26% 20% 29% 18% 6% 1	390
	21st to end	Day	28% 24% 28% 13% 5% 1	429
November	1st to 10th	Day	28% 23% 32% 11% 6% 1	395
	11th to 20th	Day	36% 21% 27% 12% 4 1	400
	21st to end	Day	35% 24% 27% 11% 3	400
December	1st to 10th	Day	34% 20% 31% 12% 3	400
	11th to 20th	Day	39% 26% 23% 10% 1	330
	21st to end	Day	28% 29% 33% 9% 1	220
January	1st to 10th	Night	27% 24% 30% 15% 4	900
	11th to 20th	Night	27% 21% 29% 18% 5%	874
	21st to end	Night	21% 22% 36% 16% 5%	880
February	1st to 10th	Night	27% 21% 34% 16% 3	800
	11th to 20th	Night	29% 25% 31% 13% 2 1	783
	21st to end	Night	22% 22% 32% 20% 3	660
March	1st to 10th	Night	28% 19% 34% 17% 1	800
	11th to 20th	Night	26% 19% 32% 19% 6%	800
	21st to end	Night	28% 17% 33% 16% 5%	880
April	1st to 10th	Night	33% 19% 28% 17% 2	632
	11th to 20th	Night	31% 17% 29% 18% 5%	594
	21st to end	Night	30% 17% 30% 17% 6%	600
May	1st to 10th	Night	31% 15% 28% 21% 4 1	600
	11th to 20th	Night	28% 15% 30% 20% 6%	592
	21st to end	Night	22% 13% 43% 18% 3	649
June	1st to 10th	Night	29% 10% 30% 26% 5%	459
	11th to 20th	Night	23% 10% 34% 28% 5%	400
	21st to end	Night	26% 9% 32% 28% 6%	400
July	1st to 10th	Night	20% 8% 39% 26% 7%	390
	11th to 20th	Night	17% 8% 37% 30% 9%	409
	21st to end	Night	17% 9% 37% 31% 6%	656
August	1st to 10th	Night	15% 6% 37% 33% 9% 1	598
	11th to 20th	Night	18% 9% 32% 29% 11% 1	592
	21st to end	Night	15% 9% 33% 32% 11% 1	660
September	1st to 10th	Night	17% 11% 38% 28% 7%	580
	11th to 20th	Night	20% 11% 27% 33% 9% 1	680
	21st to end	Night	21% 12% 32% 26% 9%	760
October	1st to 10th	Night	22% 12% 31% 26% 9%	760
	11th to 20th	Night	23% 16% 34% 20% 7%	760
	21st to end	Night	30% 20% 29% 18% 3	836
November	1st to 10th	Night	29% 19% 30% 17% 5%	867
	11th to 20th	Night	28% 20% 29% 17% 5% 1	900
	21st to end	Night	31% 22% 29% 15% 2	900
December	1st to 10th	Night	31% 18% 29% 18% 4	900
	11th to 20th	Night	32% 24% 30% 12% 2	900
	21st to end	Night	32% 22% 25% 18% 3 1	990

Page generated at 2025-09-01 02:51:03. Version ac07

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