Mont-Joli
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mont-Joli clear sky chart from 2005-11-06 to 2026-03-18.

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	16% 10% 4 9% 6% 5% 5% 4 5% 6% 29%	131004
	Night	16% 13% 5% 11% 7% 6% 5% 4 5% 5% 24%	130660
Transparency	Day	55% 9% 12% 17% 7% 1	134430
	Night	60% 7% 11% 14% 6%	135321
Seeing	Day	22% 14% 30% 24% 9% 1	17650
	Night	24% 14% 28% 25% 8% 1	25729

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% 21% 6% 16% 10% 11% 8% 3 3 2 6%	4093
	11th to 20th	Day	9% 16% 8% 20% 14% 6% 5% 4 4 4 9%	4406
	21st to end	Day	3 8% 5% 15% 12% 13% 12% 8% 5% 4 15%	5124
February	1st to 10th	Day	8% 12% 5% 12% 11% 10% 9% 5% 5% 5% 20%	1790
	11th to 20th	Day	11% 16% 5% 14% 8% 6% 7% 4 4 4 19%	1843
	21st to end	Day	8% 13% 4 11% 9% 8% 6% 4 5% 7% 25%	1717
March	1st to 10th	Day	14% 14% 4 12% 6% 7% 8% 4 5% 7% 20%	4616
	11th to 20th	Day	19% 17% 4 8% 5% 7% 6% 5% 6% 6% 17%	5057
	21st to end	Day	19% 17% 6% 12% 5% 5% 3 3 3 4 23%	5466
April	1st to 10th	Day	19% 13% 4 9% 5% 4 4 3 5% 6% 28%	2440
	11th to 20th	Day	17% 11% 3 7% 5% 4 5% 3 5% 6% 33%	2572
	21st to end	Day	21% 12% 3 7% 4 3 4 3 4 5% 33%	2600
May	1st to 10th	Day	19% 9% 3 8% 4 4 5% 3 5% 6% 33%	5886
	11th to 20th	Day	24% 8% 2 6% 4 4 5% 4 5% 6% 31%	6620
	21st to end	Day	20% 8% 2 6% 4 4 4 3 6% 8% 36%	7451
June	1st to 10th	Day	20% 8% 3 7% 5% 4 4 4 5% 7% 33%	3000
	11th to 20th	Day	18% 7% 2 6% 5% 4 4 4 6% 8% 36%	3000
	21st to end	Day	20% 7% 3 7% 5% 5% 5% 4 7% 7% 30%	3000
July	1st to 10th	Day	16% 7% 3 7% 5% 4 5% 4 6% 8% 34%	6820
	11th to 20th	Day	15% 6% 2 6% 4 5% 5% 5% 7% 9% 35%	6820
	21st to end	Day	11% 5% 2 6% 4 4 4 4 6% 8% 46%	7030
August	1st to 10th	Day	11% 5% 2 6% 5% 4 6% 5% 8% 9% 39%	4377
	11th to 20th	Day	16% 6% 3 7% 5% 4 5% 4 6% 8% 36%	4175
	21st to end	Day	16% 5% 2 7% 5% 4 4 4 6% 7% 41%	4675
September	1st to 10th	Day	16% 7% 2 5% 3 4 5% 3 5% 7% 43%	2417
	11th to 20th	Day	19% 7% 3 5% 3 3 3 2 4 5% 47%	2200
	21st to end	Day	17% 6% 3 8% 5% 4 4 3 5% 6% 40%	2200
October	1st to 10th	Day	17% 9% 3 6% 4 4 4 4 5% 7% 36%	2087
	11th to 20th	Day	25% 10% 3 7% 4 4 4 3 4 7% 29%	1935
	21st to end	Day	23% 13% 3 8% 3 4 5% 4 5% 6% 26%	1980
November	1st to 10th	Day	20% 14% 4 10% 5% 4 5% 4 5% 6% 23%	1772
	11th to 20th	Day	20% 16% 6% 12% 5% 4 5% 3 5% 6% 18%	1680
	21st to end	Day	21% 19% 5% 14% 7% 3 4 3 4 5% 16%	1564
December	1st to 10th	Day	15% 18% 6% 18% 12% 6% 3 2 3 4 14%	2350
	11th to 20th	Day	16% 14% 6% 17% 10% 7% 4 2 4 4 17%	2688
	21st to end	Day	14% 13% 6% 14% 15% 8% 5% 3 4 4 14%	3553
January	1st to 10th	Night	14% 23% 7% 14% 11% 9% 7% 2 3 3 8%	8831
	11th to 20th	Night	9% 19% 7% 17% 9% 8% 5% 4 5% 5% 13%	8474
	21st to end	Night	3 9% 5% 16% 10% 10% 12% 8% 5% 5% 16%	9057
February	1st to 10th	Night	8% 13% 6% 13% 9% 9% 6% 4 5% 4 22%	2829
	11th to 20th	Night	12% 17% 7% 12% 8% 7% 5% 3 5% 5% 19%	2663
	21st to end	Night	10% 14% 5% 12% 8% 7% 5% 3 4 5% 26%	2086
March	1st to 10th	Night	15% 14% 5% 12% 7% 6% 8% 3 4 4 23%	5443
	11th to 20th	Night	20% 18% 4 11% 6% 5% 4 3 4 5% 18%	5057
	21st to end	Night	23% 18% 4 9% 7% 3 3 2 4 5% 22%	5466
April	1st to 10th	Night	22% 14% 4 10% 6% 4 4 3 3 3 26%	1957
	11th to 20th	Night	21% 12% 3 6% 4 4 5% 4 4 5% 32%	1778
	21st to end	Night	25% 10% 3 6% 4 3 4 3 4 5% 33%	1800
May	1st to 10th	Night	20% 8% 3 7% 4 4 4 4 4 6% 34%	4054
	11th to 20th	Night	24% 9% 3 7% 4 4 3 4 5% 6% 31%	3334
	21st to end	Night	18% 7% 3 7% 5% 6% 5% 4 6% 6% 33%	3446
June	1st to 10th	Night	19% 9% 3 8% 5% 3 5% 5% 5% 7% 31%	1400
	11th to 20th	Night	19% 8% 3 7% 5% 4 4 4 6% 7% 32%	1400
	21st to end	Night	20% 9% 4 10% 5% 5% 4 4 5% 7% 28%	1400
July	1st to 10th	Night	14% 8% 3 8% 5% 6% 6% 4 6% 8% 32%	3160
	11th to 20th	Night	13% 7% 3 8% 5% 5% 6% 5% 7% 9% 32%	3160
	21st to end	Night	13% 7% 2 7% 5% 5% 5% 5% 6% 8% 39%	3811
August	1st to 10th	Night	17% 6% 3 7% 6% 5% 6% 4 7% 9% 30%	2739
	11th to 20th	Night	15% 6% 3 8% 6% 7% 5% 5% 6% 8% 31%	2872
	21st to end	Night	18% 6% 2 6% 4 4 5% 3 5% 6% 40%	3223
September	1st to 10th	Night	17% 6% 2 6% 4 4 4 4 6% 7% 40%	1980
	11th to 20th	Night	20% 7% 3 7% 4 4 3 3 4 6% 39%	2200
	21st to end	Night	19% 6% 2 6% 4 3 3 3 4 7% 44%	2200
October	1st to 10th	Night	20% 7% 3 6% 4 4 4 3 5% 6% 39%	2312
	11th to 20th	Night	26% 10% 3 7% 4 4 4 3 5% 6% 29%	2461
	21st to end	Night	22% 13% 4 8% 4 5% 5% 3 5% 6% 26%	2860
November	1st to 10th	Night	22% 14% 3 9% 6% 4 4 3 4 5% 25%	2745
	11th to 20th	Night	20% 19% 6% 9% 5% 4 4 3 3 4 22%	2940
	21st to end	Night	18% 20% 6% 14% 7% 5% 4 3 4 4 14%	3054
December	1st to 10th	Night	13% 18% 7% 19% 10% 5% 4 3 3 3 14%	5060
	11th to 20th	Night	16% 15% 6% 16% 11% 6% 4 3 3 4 15%	5741
	21st to end	Night	15% 16% 6% 13% 9% 8% 5% 3 4 5% 17%	7667

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% 11% 4 4 2	4094
	11th to 20th	Day	76% 9% 8% 5% 2	4435
	21st to end	Day	67% 12% 8% 8% 5%	5124
February	1st to 10th	Day	66% 8% 10% 11% 5% 1	1790
	11th to 20th	Day	67% 8% 10% 10% 4	1851
	21st to end	Day	59% 9% 9% 17% 7%	1717
March	1st to 10th	Day	64% 9% 11% 11% 5% 1	4619
	11th to 20th	Day	66% 10% 9% 12% 4	5057
	21st to end	Day	65% 5% 6% 15% 6% 1	5466
April	1st to 10th	Day	59% 6% 10% 13% 10% 1	2440
	11th to 20th	Day	52% 8% 10% 19% 10% 1	2572
	21st to end	Day	54% 6% 9% 18% 11% 2	2600
May	1st to 10th	Day	52% 10% 10% 18% 9% 1	5897
	11th to 20th	Day	52% 10% 12% 16% 8% 1	6624
	21st to end	Day	46% 8% 12% 24% 9% 1	7451
June	1st to 10th	Day	52% 9% 9% 17% 12% 2	3000
	11th to 20th	Day	46% 8% 12% 19% 13% 2	3000
	21st to end	Day	53% 10% 10% 15% 10% 1	3000
July	1st to 10th	Day	48% 7% 11% 25% 9%	6745
	11th to 20th	Day	44% 9% 21% 20% 5%	6739
	21st to end	Day	36% 9% 18% 29% 9%	6829
August	1st to 10th	Day	39% 10% 20% 24% 6%	4363
	11th to 20th	Day	45% 11% 20% 19% 4	4214
	21st to end	Day	42% 9% 18% 20% 10%	4675
September	1st to 10th	Day	42% 8% 16% 24% 10%	2417
	11th to 20th	Day	42% 7% 15% 26% 10%	2200
	21st to end	Day	46% 8% 12% 24% 9%	2200
October	1st to 10th	Day	51% 8% 13% 21% 6% 1	3399
	11th to 20th	Day	55% 7% 13% 23% 3	3125
	21st to end	Day	54% 8% 15% 17% 6%	3180
November	1st to 10th	Day	62% 8% 13% 12% 4	1772
	11th to 20th	Day	68% 9% 9% 11% 3	1680
	21st to end	Day	72% 6% 10% 9% 3	1564
December	1st to 10th	Day	77% 7% 8% 7% 1	2350
	11th to 20th	Day	71% 7% 8% 10% 4	2688
	21st to end	Day	71% 8% 10% 7% 4	3553
January	1st to 10th	Night	80% 8% 7% 5%	8831
	11th to 20th	Night	70% 8% 10% 9% 3	8520
	21st to end	Night	63% 10% 10% 12% 4 1	9057
February	1st to 10th	Night	64% 8% 9% 11% 7% 1	2829
	11th to 20th	Night	67% 6% 9% 12% 5%	2666
	21st to end	Night	59% 8% 8% 17% 8% 1	2086
March	1st to 10th	Night	64% 7% 8% 13% 8%	5452
	11th to 20th	Night	67% 6% 11% 10% 5%	5058
	21st to end	Night	66% 4 6% 13% 9%	5466
April	1st to 10th	Night	64% 4 8% 11% 12% 1	1957
	11th to 20th	Night	53% 5% 8% 17% 15% 1	1778
	21st to end	Night	53% 6% 8% 18% 13% 1	1800
May	1st to 10th	Night	50% 7% 13% 15% 14% 2	4060
	11th to 20th	Night	52% 6% 10% 21% 10% 1	3335
	21st to end	Night	48% 7% 12% 21% 11% 1	3447
June	1st to 10th	Night	51% 8% 11% 17% 12% 2	1400
	11th to 20th	Night	49% 7% 12% 17% 13% 2	1400
	21st to end	Night	55% 8% 10% 16% 11% 1	1400
July	1st to 10th	Night	47% 8% 14% 24% 6%	3125
	11th to 20th	Night	45% 9% 21% 22% 3	3118
	21st to end	Night	43% 8% 20% 20% 9%	3697
August	1st to 10th	Night	47% 10% 16% 21% 5%	2729
	11th to 20th	Night	47% 11% 21% 14% 6%	2899
	21st to end	Night	44% 9% 13% 21% 13%	3223
September	1st to 10th	Night	42% 7% 15% 26% 10% 1	1980
	11th to 20th	Night	47% 6% 15% 22% 9% 1	2200
	21st to end	Night	43% 6% 12% 25% 14% 1	2200
October	1st to 10th	Night	48% 6% 12% 26% 7%	3780
	11th to 20th	Night	55% 6% 12% 23% 4	4010
	21st to end	Night	56% 9% 13% 17% 4 1	4610
November	1st to 10th	Night	61% 6% 13% 14% 5% 1	2745
	11th to 20th	Night	67% 6% 10% 12% 4	2940
	21st to end	Night	73% 8% 9% 6% 3 1	3054
December	1st to 10th	Night	74% 7% 10% 8% 1	5060
	11th to 20th	Night	74% 6% 8% 9% 3	5742
	21st to end	Night	67% 8% 10% 10% 4	7667

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	25% 22% 32% 17% 4 1	220
	11th to 20th	Day	20% 25% 30% 16% 7% 1	220
	21st to end	Day	13% 25% 32% 21% 8% 1	242
February	1st to 10th	Day	14% 20% 36% 20% 8% 2	330
	11th to 20th	Day	18% 22% 37% 19% 5%	426
	21st to end	Day	16% 21% 37% 19% 6% 1	441
March	1st to 10th	Day	22% 19% 35% 21% 4	540
	11th to 20th	Day	27% 18% 28% 18% 7% 1	528
	21st to end	Day	26% 21% 28% 19% 5% 1	550
April	1st to 10th	Day	27% 20% 30% 17% 5% 1	500
	11th to 20th	Day	24% 15% 35% 20% 6% 1	492
	21st to end	Day	28% 17% 30% 19% 4 2	500
May	1st to 10th	Day	27% 16% 29% 20% 7% 1	503
	11th to 20th	Day	24% 11% 28% 26% 10% 1	694
	21st to end	Day	25% 15% 30% 21% 8% 1	790
June	1st to 10th	Day	25% 8% 32% 27% 8% 1	730
	11th to 20th	Day	23% 11% 28% 26% 12% 1	730
	21st to end	Day	21% 10% 26% 32% 9% 1	730
July	1st to 10th	Day	19% 6% 32% 32% 10% 1	720
	11th to 20th	Day	17% 8% 26% 36% 12% 1	718
	21st to end	Day	15% 7% 30% 35% 12% 1	628
August	1st to 10th	Day	15% 8% 27% 32% 15% 2	526
	11th to 20th	Day	17% 6% 26% 34% 15% 2	519
	21st to end	Day	19% 9% 27% 28% 14% 3	583
September	1st to 10th	Day	18% 12% 28% 28% 12% 2	530
	11th to 20th	Day	23% 10% 28% 25% 11% 3	530
	21st to end	Day	18% 15% 32% 22% 10% 3	530
October	1st to 10th	Day	19% 15% 31% 24% 10% 1	467
	11th to 20th	Day	34% 13% 25% 16% 10% 2	420
	21st to end	Day	33% 17% 26% 17% 7%	462
November	1st to 10th	Day	29% 24% 28% 14% 4	425
	11th to 20th	Day	30% 19% 29% 17% 5%	430
	21st to end	Day	31% 23% 29% 14% 3 1	314
December	1st to 10th	Day	26% 17% 35% 12% 8% 1	220
	11th to 20th	Day	26% 28% 31% 11% 4	220
	21st to end	Day	21% 24% 34% 17% 4	242
January	1st to 10th	Night	24% 19% 35% 19% 3	950
	11th to 20th	Night	23% 21% 30% 19% 6% 1	884
	21st to end	Night	15% 18% 33% 27% 7% 1	924
February	1st to 10th	Night	14% 19% 35% 23% 8% 1	840
	11th to 20th	Night	23% 15% 33% 22% 7% 1	823
	21st to end	Night	17% 15% 34% 25% 8% 1	692
March	1st to 10th	Night	22% 16% 31% 24% 6% 1	840
	11th to 20th	Night	26% 17% 30% 19% 7% 1	829
	21st to end	Night	25% 15% 27% 24% 7% 1	880
April	1st to 10th	Night	29% 16% 28% 20% 6%	747
	11th to 20th	Night	28% 12% 25% 24% 9% 1	594
	21st to end	Night	29% 13% 26% 24% 8% 1	600
May	1st to 10th	Night	28% 11% 24% 29% 7% 1	600
	11th to 20th	Night	23% 8% 26% 29% 14%	458
	21st to end	Night	25% 9% 29% 28% 9% 1	433
June	1st to 10th	Night	22% 4 27% 38% 8%	400
	11th to 20th	Night	22% 8% 21% 33% 15% 1	400
	21st to end	Night	21% 6% 31% 33% 9% 1	400
July	1st to 10th	Night	18% 6% 29% 36% 9% 2	390
	11th to 20th	Night	15% 6% 25% 41% 12% 1	388
	21st to end	Night	18% 4 24% 38% 16% 1	438
August	1st to 10th	Night	18% 6% 23% 31% 19% 2	486
	11th to 20th	Night	17% 4 21% 37% 19% 1	592
	21st to end	Night	17% 6% 23% 35% 16% 3	660
September	1st to 10th	Night	21% 8% 26% 33% 12%	695
	11th to 20th	Night	22% 9% 25% 30% 13% 2	800
	21st to end	Night	21% 10% 26% 31% 11% 1	800
October	1st to 10th	Night	25% 11% 27% 28% 8% 1	800
	11th to 20th	Night	32% 10% 23% 23% 11% 1	800
	21st to end	Night	30% 17% 25% 21% 6%	880
November	1st to 10th	Night	31% 19% 27% 18% 5%	861
	11th to 20th	Night	28% 21% 26% 18% 5% 1	950
	21st to end	Night	28% 18% 31% 17% 5% 1	950
December	1st to 10th	Night	27% 16% 32% 18% 5% 1	950
	11th to 20th	Night	27% 22% 29% 17% 4 1	950
	21st to end	Night	25% 21% 25% 22% 5% 1	1045

Page generated at 2026-03-15 02:23:54. Version ac07

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