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 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	17% 10% 4 8% 7% 4 5% 5% 5% 6% 30%	74623
	Night	18% 12% 5% 9% 7% 4 5% 5% 5% 5% 25%	75185
Transparency	Day	56% 9% 11% 16% 8% 1	74313
	Night	61% 7% 10% 14% 7% 1	75029
Seeing	Day	22% 14% 30% 24% 9% 1	14819
	Night	24% 14% 28% 25% 8% 1	22896

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% 20% 7% 13% 10% 6% 7% 5% 4 4 9%	1327
	11th to 20th	Day	15% 15% 7% 13% 12% 5% 7% 8% 4 5% 11%	1399
	21st to end	Day	9% 11% 5% 10% 9% 7% 10% 7% 5% 5% 21%	1584
February	1st to 10th	Day	9% 11% 5% 10% 10% 8% 10% 7% 5% 5% 20%	1534
	11th to 20th	Day	13% 14% 6% 13% 9% 5% 6% 6% 4 4 20%	1573
	21st to end	Day	10% 12% 4 9% 10% 5% 8% 5% 5% 7% 24%	1468
March	1st to 10th	Day	15% 13% 5% 8% 7% 4 6% 5% 5% 7% 24%	1808
	11th to 20th	Day	16% 14% 5% 9% 7% 4 5% 5% 4 5% 24%	1980
	21st to end	Day	15% 15% 6% 7% 6% 4 4 4 4 6% 30%	2178
April	1st to 10th	Day	20% 12% 5% 8% 6% 3 5% 4 5% 7% 25%	2194
	11th to 20th	Day	17% 10% 3 6% 6% 2 5% 5% 5% 6% 34%	2312
	21st to end	Day	21% 11% 3 7% 5% 2 4 4 4 5% 33%	2340
May	1st to 10th	Day	22% 10% 4 7% 4 3 4 3 4 6% 32%	2340
	11th to 20th	Day	20% 7% 3 5% 6% 3 5% 4 4 7% 36%	2584
	21st to end	Day	21% 7% 3 5% 4 3 4 4 5% 7% 36%	2919
June	1st to 10th	Day	20% 7% 4 6% 5% 3 5% 4 5% 7% 32%	2700
	11th to 20th	Day	18% 7% 2 5% 5% 3 4 5% 5% 8% 37%	2700
	21st to end	Day	20% 6% 3 6% 6% 4 5% 5% 7% 8% 30%	2700
July	1st to 10th	Day	15% 6% 3 7% 6% 4 5% 5% 6% 9% 34%	2700
	11th to 20th	Day	14% 6% 3 5% 5% 4 5% 6% 6% 9% 38%	2700
	21st to end	Day	13% 6% 3 6% 6% 3 5% 5% 7% 8% 38%	2792
August	1st to 10th	Day	14% 5% 3 6% 7% 4 5% 6% 8% 9% 34%	2409
	11th to 20th	Day	14% 5% 3 6% 6% 3 5% 5% 6% 8% 40%	2304
	21st to end	Day	15% 6% 2 6% 5% 4 5% 5% 6% 8% 37%	2574
September	1st to 10th	Day	18% 7% 3 4 4 3 4 4 5% 7% 42%	2176
	11th to 20th	Day	21% 7% 3 4 4 2 3 3 4 5% 45%	1980
	21st to end	Day	17% 6% 3 6% 6% 3 4 4 5% 6% 40%	1980
October	1st to 10th	Day	17% 8% 3 6% 5% 3 4 5% 5% 7% 37%	1879
	11th to 20th	Day	25% 10% 3 6% 5% 3 4 4 4 7% 29%	1742
	21st to end	Day	24% 12% 3 7% 4 3 5% 5% 5% 6% 25%	1782
November	1st to 10th	Day	19% 13% 5% 9% 7% 3 5% 5% 5% 6% 24%	1600
	11th to 20th	Day	20% 13% 7% 12% 6% 3 5% 4 4 6% 18%	1520
	21st to end	Day	21% 16% 6% 12% 9% 3 5% 4 3 5% 17%	1416
December	1st to 10th	Day	19% 15% 7% 13% 12% 6% 6% 3 3 5% 10%	1330
	11th to 20th	Day	17% 15% 7% 13% 11% 7% 5% 4 3 3 15%	1668
	21st to end	Day	17% 13% 6% 11% 13% 5% 5% 5% 4 4 17%	2431
January	1st to 10th	Night	14% 18% 8% 12% 12% 7% 7% 4 4 4 10%	2838
	11th to 20th	Night	15% 16% 7% 10% 11% 5% 8% 6% 5% 4 15%	2678
	21st to end	Night	8% 14% 6% 11% 10% 7% 11% 6% 5% 5% 19%	2772
February	1st to 10th	Night	9% 13% 6% 12% 10% 8% 7% 6% 5% 4 20%	2426
	11th to 20th	Night	13% 15% 7% 10% 9% 5% 6% 4 5% 5% 20%	2273
	21st to end	Night	11% 13% 6% 10% 10% 6% 6% 4 4 5% 24%	1785
March	1st to 10th	Night	14% 14% 7% 10% 7% 4 7% 5% 4 4 26%	2138
	11th to 20th	Night	16% 17% 6% 10% 7% 5% 5% 4 3 4 25%	1979
	21st to end	Night	16% 15% 6% 7% 6% 3 5% 4 4 5% 29%	2178
April	1st to 10th	Night	23% 14% 5% 9% 7% 3 4 4 3 3 24%	1763
	11th to 20th	Night	21% 11% 4 6% 4 2 4 5% 4 5% 34%	1598
	21st to end	Night	25% 8% 4 6% 4 2 4 3 4 6% 34%	1620
May	1st to 10th	Night	26% 10% 5% 7% 5% 3 4 5% 4 4 27%	1620
	11th to 20th	Night	19% 8% 4 6% 6% 3 4 4 4 7% 34%	1324
	21st to end	Night	22% 8% 3 6% 5% 4 5% 5% 6% 7% 30%	1356
June	1st to 10th	Night	20% 9% 3 7% 6% 2 5% 5% 5% 7% 30%	1260
	11th to 20th	Night	20% 8% 3 5% 6% 3 3 6% 6% 7% 33%	1260
	21st to end	Night	20% 8% 4 7% 7% 3 5% 4 5% 7% 28%	1260
July	1st to 10th	Night	16% 8% 4 7% 8% 4 5% 5% 6% 8% 29%	1260
	11th to 20th	Night	12% 8% 3 5% 5% 4 7% 6% 8% 9% 32%	1260
	21st to end	Night	17% 8% 2 6% 5% 3 6% 8% 7% 9% 30%	1524
August	1st to 10th	Night	15% 6% 4 6% 6% 3 5% 6% 8% 9% 31%	1510
	11th to 20th	Night	16% 7% 3 5% 5% 4 6% 5% 6% 9% 33%	1596
	21st to end	Night	16% 7% 3 6% 6% 3 4 6% 6% 7% 36%	1782
September	1st to 10th	Night	18% 7% 2 5% 5% 3 4 5% 5% 7% 39%	1781
	11th to 20th	Night	22% 7% 3 6% 5% 3 4 3 4 6% 38%	1980
	21st to end	Night	20% 5% 3 5% 4 3 3 3 4 6% 44%	1980
October	1st to 10th	Night	20% 6% 3 5% 5% 3 5% 5% 5% 6% 38%	2080
	11th to 20th	Night	26% 10% 3 7% 5% 3 4 4 5% 6% 27%	2214
	21st to end	Night	23% 12% 4 7% 5% 3 5% 4 5% 6% 26%	2574
November	1st to 10th	Night	22% 12% 4 8% 7% 4 5% 4 4 6% 26%	2477
	11th to 20th	Night	20% 17% 7% 9% 6% 3 4 4 3 5% 22%	2660
	21st to end	Night	18% 18% 7% 13% 9% 4 4 4 4 5% 15%	2762
December	1st to 10th	Night	20% 16% 8% 14% 11% 5% 4 4 4 3 11%	2850
	11th to 20th	Night	17% 17% 6% 14% 13% 6% 6% 4 3 4 11%	3531
	21st to end	Night	16% 17% 6% 11% 9% 5% 6% 5% 5% 5% 17%	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	79% 8% 5% 6% 2	1328
	11th to 20th	Day	76% 6% 8% 6% 4	1399
	21st to end	Day	63% 9% 8% 11% 7%	1584
February	1st to 10th	Day	65% 7% 10% 10% 5% 1	1534
	11th to 20th	Day	68% 7% 9% 10% 5%	1581
	21st to end	Day	59% 9% 8% 16% 7% 1	1468
March	1st to 10th	Day	62% 9% 10% 12% 6% 1	1811
	11th to 20th	Day	63% 7% 8% 14% 7% 1	1980
	21st to end	Day	59% 6% 8% 17% 9% 1	2178
April	1st to 10th	Day	61% 7% 10% 12% 9% 1	2194
	11th to 20th	Day	51% 8% 10% 19% 10% 1	2312
	21st to end	Day	55% 6% 8% 18% 11% 2	2340
May	1st to 10th	Day	56% 6% 8% 17% 11% 2	2340
	11th to 20th	Day	51% 6% 9% 21% 12% 1	2588
	21st to end	Day	50% 8% 10% 21% 12% 1	2919
June	1st to 10th	Day	53% 9% 9% 16% 12% 2	2700
	11th to 20th	Day	47% 8% 12% 19% 13% 2	2700
	21st to end	Day	54% 10% 11% 15% 10% 1	2700
July	1st to 10th	Day	48% 10% 15% 19% 7%	2625
	11th to 20th	Day	43% 11% 15% 21% 9%	2619
	21st to end	Day	46% 13% 12% 20% 8%	2636
August	1st to 10th	Day	46% 13% 15% 21% 5%	2395
	11th to 20th	Day	44% 11% 17% 22% 6%	2304
	21st to end	Day	45% 11% 15% 22% 7%	2574
September	1st to 10th	Day	44% 8% 14% 24% 10% 1	2176
	11th to 20th	Day	44% 7% 13% 25% 10%	1980
	21st to end	Day	46% 8% 12% 23% 10%	1980
October	1st to 10th	Day	48% 9% 14% 19% 9% 1	1879
	11th to 20th	Day	57% 8% 14% 16% 4	1742
	21st to end	Day	61% 9% 10% 14% 6% 1	1782
November	1st to 10th	Day	63% 8% 12% 12% 5%	1600
	11th to 20th	Day	68% 9% 9% 11% 3	1520
	21st to end	Day	71% 7% 11% 9% 3	1416
December	1st to 10th	Day	79% 8% 6% 5% 1	1330
	11th to 20th	Day	75% 8% 6% 8% 3	1668
	21st to end	Day	68% 9% 11% 7% 4	2431
January	1st to 10th	Night	79% 7% 6% 6% 1	2838
	11th to 20th	Night	72% 8% 8% 9% 3	2678
	21st to end	Night	67% 7% 8% 13% 5%	2772
February	1st to 10th	Night	65% 8% 8% 10% 7% 1	2426
	11th to 20th	Night	67% 6% 10% 11% 5%	2276
	21st to end	Night	61% 8% 7% 16% 7% 1	1785
March	1st to 10th	Night	63% 5% 7% 17% 8%	2147
	11th to 20th	Night	65% 4 9% 14% 8% 1	1980
	21st to end	Night	59% 4 8% 17% 11% 1	2178
April	1st to 10th	Night	66% 4 8% 9% 11% 1	1763
	11th to 20th	Night	52% 5% 8% 17% 16% 1	1598
	21st to end	Night	53% 6% 8% 18% 14% 2	1620
May	1st to 10th	Night	60% 5% 7% 15% 11% 2	1620
	11th to 20th	Night	51% 5% 9% 21% 12% 1	1325
	21st to end	Night	54% 6% 9% 17% 13% 2	1357
June	1st to 10th	Night	52% 7% 11% 18% 10% 2	1260
	11th to 20th	Night	48% 6% 11% 18% 13% 2	1260
	21st to end	Night	55% 8% 11% 16% 11%	1260
July	1st to 10th	Night	52% 9% 14% 19% 6%	1225
	11th to 20th	Night	46% 8% 15% 22% 8% 1	1218
	21st to end	Night	50% 10% 16% 19% 7%	1439
August	1st to 10th	Night	45% 11% 18% 21% 4	1500
	11th to 20th	Night	46% 10% 18% 19% 7%	1596
	21st to end	Night	45% 10% 13% 23% 8%	1782
September	1st to 10th	Night	44% 8% 14% 24% 10% 1	1781
	11th to 20th	Night	49% 6% 15% 21% 9% 1	1980
	21st to end	Night	43% 6% 12% 24% 14% 1	1980
October	1st to 10th	Night	48% 7% 12% 21% 11% 1	2080
	11th to 20th	Night	59% 7% 12% 16% 5%	2214
	21st to end	Night	60% 7% 13% 14% 5% 1	2574
November	1st to 10th	Night	61% 7% 14% 13% 5% 1	2477
	11th to 20th	Night	67% 7% 11% 12% 4	2660
	21st to end	Night	73% 8% 9% 6% 3 1	2762
December	1st to 10th	Night	78% 6% 7% 7% 2	2850
	11th to 20th	Night	79% 5% 6% 7% 3	3532
	21st to end	Night	65% 9% 13% 7% 5% 1	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	23% 21% 33% 19% 3 1	180
	11th to 20th	Day	24% 23% 30% 17% 5% 1	170
	21st to end	Day	14% 24% 33% 21% 7% 1	176
February	1st to 10th	Day	17% 19% 39% 20% 5%	254
	11th to 20th	Day	17% 23% 37% 18% 5%	336
	21st to end	Day	17% 20% 36% 18% 8% 1	342
March	1st to 10th	Day	22% 18% 34% 21% 5%	420
	11th to 20th	Day	24% 18% 30% 20% 8% 1	420
	21st to end	Day	24% 20% 28% 21% 6% 1	462
April	1st to 10th	Day	26% 19% 32% 16% 5% 1	420
	11th to 20th	Day	23% 14% 36% 19% 7% 1	412
	21st to end	Day	26% 16% 31% 20% 5% 2	420
May	1st to 10th	Day	28% 14% 30% 21% 6% 1	423
	11th to 20th	Day	24% 11% 27% 27% 10% 1	596
	21st to end	Day	26% 15% 29% 20% 8% 1	680
June	1st to 10th	Day	26% 8% 33% 26% 7% 1	630
	11th to 20th	Day	23% 10% 26% 28% 12%	630
	21st to end	Day	21% 8% 26% 34% 10% 1	630
July	1st to 10th	Day	18% 6% 33% 31% 11% 1	620
	11th to 20th	Day	17% 7% 24% 38% 13% 1	618
	21st to end	Day	15% 6% 27% 37% 14% 1	536
August	1st to 10th	Day	16% 9% 26% 33% 15% 2	446
	11th to 20th	Day	18% 6% 26% 34% 15% 1	439
	21st to end	Day	20% 8% 25% 30% 14% 3	495
September	1st to 10th	Day	20% 11% 26% 28% 13% 2	450
	11th to 20th	Day	25% 11% 28% 25% 9% 2	450
	21st to end	Day	17% 16% 33% 21% 11% 2	450
October	1st to 10th	Day	19% 15% 29% 25% 10% 2	399
	11th to 20th	Day	33% 13% 26% 16% 11% 1	360
	21st to end	Day	34% 17% 26% 15% 8% 1	396
November	1st to 10th	Day	27% 23% 30% 15% 5%	365
	11th to 20th	Day	28% 18% 30% 17% 6% 1	370
	21st to end	Day	27% 24% 29% 16% 3 1	266
December	1st to 10th	Day	26% 16% 36% 12% 9% 1	180
	11th to 20th	Day	26% 28% 32% 10% 4	180
	21st to end	Day	22% 25% 35% 14% 3	198
January	1st to 10th	Night	23% 19% 35% 19% 3	850
	11th to 20th	Night	25% 19% 31% 20% 4	780
	21st to end	Night	15% 18% 33% 27% 7%	792
February	1st to 10th	Night	15% 20% 36% 22% 6% 1	720
	11th to 20th	Night	24% 15% 33% 21% 7% 1	703
	21st to end	Night	17% 16% 33% 26% 8% 1	592
March	1st to 10th	Night	21% 14% 32% 25% 7% 1	720
	11th to 20th	Night	24% 17% 31% 19% 8% 1	720
	21st to end	Night	23% 15% 28% 25% 7% 1	792
April	1st to 10th	Night	29% 16% 28% 19% 7%	673
	11th to 20th	Night	28% 11% 26% 24% 10% 1	534
	21st to end	Night	29% 12% 26% 24% 8% 1	540
May	1st to 10th	Night	30% 9% 24% 30% 7% 1	540
	11th to 20th	Night	23% 8% 26% 29% 13%	412
	21st to end	Night	26% 9% 28% 26% 9% 1	389
June	1st to 10th	Night	23% 4 26% 39% 8%	360
	11th to 20th	Night	23% 6% 21% 34% 15% 1	360
	21st to end	Night	21% 5% 29% 34% 10% 1	360
July	1st to 10th	Night	18% 6% 29% 35% 10% 2	350
	11th to 20th	Night	16% 5% 24% 41% 12% 1	348
	21st to end	Night	19% 4 20% 39% 17% 2	394
August	1st to 10th	Night	19% 6% 22% 31% 19% 2	436
	11th to 20th	Night	18% 4 22% 36% 20% 2	532
	21st to end	Night	18% 6% 23% 35% 16% 3	594
September	1st to 10th	Night	22% 6% 26% 33% 12%	625
	11th to 20th	Night	24% 8% 26% 28% 11% 3	720
	21st to end	Night	22% 10% 27% 31% 10% 1	720
October	1st to 10th	Night	26% 11% 26% 27% 8% 1	720
	11th to 20th	Night	32% 10% 24% 22% 11% 1	720
	21st to end	Night	31% 17% 24% 21% 7% 1	792
November	1st to 10th	Night	29% 19% 27% 19% 5% 1	773
	11th to 20th	Night	27% 21% 27% 18% 5% 1	850
	21st to end	Night	26% 18% 32% 18% 5% 1	850
December	1st to 10th	Night	29% 17% 30% 18% 6% 1	850
	11th to 20th	Night	26% 22% 29% 18% 4 1	850
	21st to end	Night	26% 21% 24% 22% 5% 2	935

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