Fort Frances
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Frances clear sky chart from 2005-11-06 to 2024-11-05.

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	13% 10% 4 9% 5% 5% 5% 4 6% 7% 33%	101837
	Night	13% 11% 4 10% 6% 5% 5% 4 5% 6% 31%	97358
Transparency	Day	48% 7% 14% 22% 8% 1	105321
	Night	52% 6% 13% 20% 8% 1	101963
Seeing	Day	18% 12% 31% 25% 12% 3	16203
	Night	18% 9% 32% 29% 11% 1	26091

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	7% 14% 7% 16% 8% 8% 5% 4 5% 6% 20%	2218
	11th to 20th	Day	6% 11% 5% 13% 11% 8% 10% 7% 7% 6% 17%	2220
	21st to end	Day	8% 17% 10% 16% 8% 6% 6% 4 5% 6% 13%	2893
February	1st to 10th	Day	8% 13% 5% 12% 7% 5% 10% 6% 6% 7% 21%	1710
	11th to 20th	Day	9% 11% 4 11% 7% 7% 5% 4 5% 6% 30%	1664
	21st to end	Day	8% 13% 4 12% 7% 5% 5% 3 4 7% 32%	1418
March	1st to 10th	Day	10% 11% 3 6% 4 4 4 3 5% 8% 41%	3302
	11th to 20th	Day	6% 10% 5% 14% 8% 5% 4 4 6% 6% 32%	3480
	21st to end	Day	15% 14% 5% 9% 5% 3 3 3 4 6% 32%	3877
April	1st to 10th	Day	15% 10% 3 9% 5% 5% 5% 4 5% 7% 33%	2280
	11th to 20th	Day	16% 11% 3 7% 5% 5% 5% 4 6% 7% 31%	2356
	21st to end	Day	17% 12% 3 6% 5% 5% 4 4 4 6% 33%	2489
May	1st to 10th	Day	18% 9% 3 7% 4 5% 4 4 6% 8% 34%	4428
	11th to 20th	Day	15% 8% 3 8% 5% 5% 5% 4 6% 7% 34%	4399
	21st to end	Day	20% 8% 3 7% 4 3 4 3 5% 6% 37%	4899
June	1st to 10th	Day	15% 6% 2 6% 5% 5% 4 5% 7% 8% 37%	2850
	11th to 20th	Day	16% 6% 3 6% 5% 5% 5% 4 5% 7% 37%	2850
	21st to end	Day	15% 7% 3 7% 5% 6% 6% 5% 7% 8% 33%	2850
July	1st to 10th	Day	8% 5% 2 5% 5% 6% 6% 5% 9% 10% 39%	4750
	11th to 20th	Day	10% 4 2 5% 4 4 4 3 6% 10% 47%	4750
	21st to end	Day	12% 6% 3 6% 4 4 5% 4 6% 9% 39%	4885
August	1st to 10th	Day	11% 6% 2 7% 5% 5% 6% 5% 7% 9% 38%	4306
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 5% 7% 11% 42%	4041
	21st to end	Day	14% 6% 2 6% 4 4 5% 3 6% 8% 40%	4441
September	1st to 10th	Day	12% 6% 2 6% 4 4 5% 3 5% 7% 44%	2280
	11th to 20th	Day	15% 7% 3 7% 4 4 4 4 5% 8% 38%	2256
	21st to end	Day	20% 7% 3 8% 3 3 4 4 5% 6% 37%	1998
October	1st to 10th	Day	19% 11% 3 8% 5% 4 3 3 5% 7% 31%	1900
	11th to 20th	Day	18% 14% 4 9% 5% 4 4 4 5% 5% 27%	1900
	21st to end	Day	19% 18% 4 10% 6% 4 4 2 4 5% 25%	1947
November	1st to 10th	Day	15% 17% 5% 11% 6% 4 5% 4 4 5% 23%	1519
	11th to 20th	Day	14% 19% 8% 15% 6% 5% 3 2 5% 4 19%	1520
	21st to end	Day	14% 16% 8% 17% 8% 5% 4 3 4 4 17%	1520
December	1st to 10th	Day	11% 15% 6% 16% 9% 6% 7% 5% 4 5% 14%	1520
	11th to 20th	Day	10% 18% 8% 15% 7% 6% 5% 4 4 4 20%	1679
	21st to end	Day	20% 20% 7% 13% 8% 4 4 2 4 4 15%	2442
January	1st to 10th	Night	6% 16% 7% 16% 9% 6% 5% 4 5% 5% 23%	4737
	11th to 20th	Night	7% 12% 6% 14% 12% 10% 9% 6% 5% 4 14%	4750
	21st to end	Night	9% 21% 13% 14% 6% 5% 5% 4 5% 5% 16%	4767
February	1st to 10th	Night	8% 11% 5% 12% 8% 7% 7% 5% 6% 6% 25%	2470
	11th to 20th	Night	8% 9% 4 11% 6% 5% 6% 5% 5% 6% 34%	2403
	21st to end	Night	8% 13% 5% 12% 7% 7% 5% 4 5% 6% 29%	2036
March	1st to 10th	Night	12% 9% 4 10% 5% 5% 4 4 4 7% 35%	3567
	11th to 20th	Night	7% 11% 4 11% 9% 7% 6% 4 6% 7% 29%	3479
	21st to end	Night	18% 15% 4 10% 5% 3 4 3 4 5% 29%	3754
April	1st to 10th	Night	16% 11% 3 10% 5% 3 5% 3 6% 6% 33%	1900
	11th to 20th	Night	16% 11% 4 8% 4 5% 4 3 5% 6% 34%	1772
	21st to end	Night	18% 12% 4 7% 5% 5% 5% 3 4 6% 32%	1691
May	1st to 10th	Night	19% 8% 2 5% 4 4 4 3 5% 7% 39%	2523
	11th to 20th	Night	14% 8% 3 6% 4 5% 5% 4 7% 8% 36%	2506
	21st to end	Night	22% 7% 2 6% 3 3 4 4 5% 6% 38%	2672
June	1st to 10th	Night	15% 7% 2 7% 5% 3 3 3 6% 7% 42%	1330
	11th to 20th	Night	12% 6% 2 6% 4 4 4 4 5% 7% 45%	1330
	21st to end	Night	15% 6% 2 5% 3 4 4 4 6% 9% 42%	1330
July	1st to 10th	Night	9% 3 1 4 5% 5% 4 5% 8% 11% 46%	2220
	11th to 20th	Night	6% 4 2 5% 3 3 5% 4 6% 10% 53%	2220
	21st to end	Night	9% 4 2 6% 4 3 3 4 5% 9% 50%	2679
August	1st to 10th	Night	11% 5% 2 6% 4 5% 5% 4 6% 8% 44%	2631
	11th to 20th	Night	12% 5% 2 5% 3 4 4 4 6% 9% 48%	2798
	21st to end	Night	14% 5% 2 6% 4 4 4 3 5% 7% 46%	3222
September	1st to 10th	Night	12% 6% 2 7% 4 4 3 3 5% 6% 48%	1900
	11th to 20th	Night	14% 6% 2 6% 4 3 4 3 4 8% 45%	1922
	21st to end	Night	18% 9% 3 6% 4 4 3 3 5% 6% 40%	2162
October	1st to 10th	Night	16% 12% 4 6% 3 4 5% 3 6% 6% 35%	2280
	11th to 20th	Night	18% 14% 4 7% 3 4 4 3 4 7% 31%	2280
	21st to end	Night	19% 14% 4 10% 5% 5% 4 4 5% 5% 25%	2649
November	1st to 10th	Night	15% 17% 5% 10% 6% 5% 4 3 4 5% 26%	2660
	11th to 20th	Night	15% 17% 6% 14% 7% 6% 4 4 4 6% 17%	2660
	21st to end	Night	14% 16% 5% 14% 8% 6% 6% 3 4 5% 19%	2660
December	1st to 10th	Night	8% 16% 6% 17% 10% 8% 6% 4 5% 6% 14%	2660
	11th to 20th	Night	11% 14% 6% 15% 9% 7% 6% 4 5% 6% 17%	3513
	21st to end	Night	20% 19% 7% 14% 7% 5% 5% 3 4 4 13%	5225

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	64% 7% 8% 15% 6%	2219
	11th to 20th	Day	65% 9% 8% 16% 3	2220
	21st to end	Day	70% 7% 9% 10% 4	2893
February	1st to 10th	Day	59% 7% 10% 15% 8% 1	1710
	11th to 20th	Day	54% 5% 11% 20% 9% 1	1673
	21st to end	Day	53% 6% 13% 17% 12%	1418
March	1st to 10th	Day	42% 5% 11% 25% 16% 1	3304
	11th to 20th	Day	50% 6% 14% 21% 9%	3480
	21st to end	Day	54% 4 10% 20% 9% 2	3877
April	1st to 10th	Day	51% 5% 9% 18% 15% 1	2280
	11th to 20th	Day	51% 7% 11% 19% 11% 1	2356
	21st to end	Day	52% 6% 8% 22% 11% 1	2489
May	1st to 10th	Day	47% 7% 13% 21% 11% 1	4440
	11th to 20th	Day	46% 9% 12% 21% 10% 2	4403
	21st to end	Day	46% 7% 11% 25% 10% 1	4899
June	1st to 10th	Day	43% 10% 14% 22% 10% 1	2850
	11th to 20th	Day	46% 7% 13% 21% 12%	2850
	21st to end	Day	46% 9% 15% 23% 7%	2850
July	1st to 10th	Day	37% 11% 19% 25% 8%	4676
	11th to 20th	Day	30% 8% 20% 34% 8%	4669
	21st to end	Day	39% 9% 15% 30% 6%	4730
August	1st to 10th	Day	41% 8% 16% 23% 11% 1	4291
	11th to 20th	Day	35% 9% 24% 26% 6%	4080
	21st to end	Day	40% 7% 19% 27% 7%	4440
September	1st to 10th	Day	38% 8% 14% 30% 10%	2280
	11th to 20th	Day	43% 8% 21% 22% 5%	2256
	21st to end	Day	47% 7% 13% 27% 6%	1998
October	1st to 10th	Day	41% 5% 17% 27% 11%	3160
	11th to 20th	Day	48% 6% 13% 21% 12%	3140
	21st to end	Day	57% 6% 15% 19% 3	3189
November	1st to 10th	Day	62% 7% 12% 14% 5% 1	1519
	11th to 20th	Day	69% 6% 8% 12% 5%	1520
	21st to end	Day	70% 6% 11% 10% 3	1520
December	1st to 10th	Day	70% 7% 9% 11% 3	1520
	11th to 20th	Day	68% 6% 9% 14% 3	1680
	21st to end	Day	74% 4 6% 11% 5%	2442
January	1st to 10th	Night	63% 5% 12% 16% 4	4737
	11th to 20th	Night	70% 7% 9% 12% 3	4750
	21st to end	Night	70% 5% 10% 11% 3	4767
February	1st to 10th	Night	57% 5% 13% 15% 9% 1	2470
	11th to 20th	Night	50% 5% 15% 20% 9% 1	2404
	21st to end	Night	56% 5% 10% 19% 8% 1	2036
March	1st to 10th	Night	48% 6% 13% 18% 14% 1	3578
	11th to 20th	Night	53% 7% 13% 18% 7% 1	3480
	21st to end	Night	59% 5% 8% 16% 11% 1	3754
April	1st to 10th	Night	51% 6% 9% 17% 16% 1	1900
	11th to 20th	Night	50% 5% 9% 20% 13% 2	1772
	21st to end	Night	54% 5% 7% 20% 13% 1	1691
May	1st to 10th	Night	43% 7% 10% 24% 15%	2530
	11th to 20th	Night	41% 9% 13% 23% 11% 3	2507
	21st to end	Night	45% 8% 10% 25% 10% 1	2673
June	1st to 10th	Night	40% 8% 16% 22% 13% 1	1330
	11th to 20th	Night	37% 8% 13% 26% 16% 2	1330
	21st to end	Night	38% 7% 19% 26% 9% 1	1330
July	1st to 10th	Night	28% 10% 24% 29% 8%	2185
	11th to 20th	Night	24% 8% 17% 37% 13%	2178
	21st to end	Night	31% 7% 18% 35% 8% 1	2594
August	1st to 10th	Night	36% 8% 16% 29% 11% 1	2622
	11th to 20th	Night	32% 8% 21% 33% 6%	2825
	21st to end	Night	37% 7% 20% 27% 8%	3222
September	1st to 10th	Night	37% 6% 17% 29% 11%	1900
	11th to 20th	Night	37% 8% 19% 27% 8%	1922
	21st to end	Night	45% 6% 14% 28% 7%	2162
October	1st to 10th	Night	38% 6% 13% 34% 10% 1	3800
	11th to 20th	Night	48% 5% 14% 25% 8%	3779
	21st to end	Night	56% 6% 11% 23% 5%	4359
November	1st to 10th	Night	60% 5% 12% 17% 6% 1	2660
	11th to 20th	Night	69% 7% 10% 10% 4	2660
	21st to end	Night	66% 7% 13% 10% 4	2660
December	1st to 10th	Night	70% 8% 10% 10% 2	2660
	11th to 20th	Night	67% 6% 11% 12% 4	3511
	21st to end	Night	75% 6% 7% 10% 3	5225

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	14% 12% 38% 24% 11% 1	270
	11th to 20th	Day	17% 10% 33% 32% 7% 1	270
	21st to end	Day	17% 11% 34% 23% 14% 1	297
February	1st to 10th	Day	16% 11% 43% 24% 6%	270
	11th to 20th	Day	15% 18% 35% 19% 8% 5%	270
	21st to end	Day	20% 18% 39% 19% 4 1	225
March	1st to 10th	Day	16% 12% 37% 25% 9% 2	270
	11th to 20th	Day	14% 15% 35% 21% 11% 4	270
	21st to end	Day	18% 16% 32% 23% 10% 2	335
April	1st to 10th	Day	21% 12% 33% 22% 11%	460
	11th to 20th	Day	21% 16% 29% 24% 8% 1	554
	21st to end	Day	22% 11% 30% 23% 12% 1	650
May	1st to 10th	Day	23% 17% 32% 18% 9% 2	653
	11th to 20th	Day	22% 11% 29% 24% 11% 3	675
	21st to end	Day	23% 9% 25% 31% 9% 2	734
June	1st to 10th	Day	17% 11% 29% 27% 13% 3	680
	11th to 20th	Day	18% 14% 33% 23% 10% 2	680
	21st to end	Day	18% 8% 26% 28% 14% 5%	680
July	1st to 10th	Day	11% 7% 27% 30% 17% 7%	671
	11th to 20th	Day	15% 9% 27% 26% 17% 5%	668
	21st to end	Day	11% 9% 27% 29% 17% 7%	739
August	1st to 10th	Day	9% 10% 26% 34% 17% 4	676
	11th to 20th	Day	13% 7% 25% 29% 17% 8%	665
	21st to end	Day	16% 10% 28% 26% 17% 3	696
September	1st to 10th	Day	15% 11% 29% 28% 15% 2	490
	11th to 20th	Day	17% 10% 32% 28% 12% 2	466
	21st to end	Day	27% 11% 33% 21% 8% 1	300
October	1st to 10th	Day	24% 13% 28% 24% 8% 3	300
	11th to 20th	Day	21% 18% 33% 23% 4	300
	21st to end	Day	32% 17% 32% 15% 4 1	330
November	1st to 10th	Day	22% 15% 33% 21% 7% 1	282
	11th to 20th	Day	24% 17% 32% 19% 7%	270
	21st to end	Day	26% 16% 34% 20% 4 1	270
December	1st to 10th	Day	19% 13% 33% 27% 8%	270
	11th to 20th	Day	19% 14% 42% 20% 4	270
	21st to end	Day	20% 12% 36% 22% 7% 3	297
January	1st to 10th	Night	14% 12% 37% 25% 10% 2	950
	11th to 20th	Night	17% 9% 38% 26% 9% 1	950
	21st to end	Night	18% 9% 36% 28% 8%	1045
February	1st to 10th	Night	13% 10% 35% 31% 11% 1	950
	11th to 20th	Night	13% 9% 36% 28% 10% 3	929
	21st to end	Night	14% 9% 36% 28% 11% 3	780
March	1st to 10th	Night	16% 10% 34% 29% 10% 1	670
	11th to 20th	Night	15% 12% 35% 31% 6% 1	570
	21st to end	Night	21% 11% 30% 24% 11% 3	627
April	1st to 10th	Night	19% 11% 33% 28% 9% 1	570
	11th to 20th	Night	21% 10% 33% 26% 10% 1	563
	21st to end	Night	23% 9% 25% 33% 10%	570
May	1st to 10th	Night	21% 8% 31% 31% 8% 1	570
	11th to 20th	Night	20% 8% 30% 32% 8% 2	561
	21st to end	Night	19% 7% 27% 37% 9%	617
June	1st to 10th	Night	17% 9% 27% 33% 13% 1	570
	11th to 20th	Night	14% 8% 31% 33% 14%	570
	21st to end	Night	15% 5% 27% 34% 18% 1	570
July	1st to 10th	Night	8% 3 26% 39% 23% 1	555
	11th to 20th	Night	11% 3 27% 39% 19% 1	552
	21st to end	Night	8% 4 26% 36% 23% 3	624
August	1st to 10th	Night	8% 2 28% 41% 19% 2	567
	11th to 20th	Night	13% 6% 21% 34% 23% 3	564
	21st to end	Night	14% 7% 26% 34% 19% 1	627
September	1st to 10th	Night	16% 6% 25% 35% 15% 2	570
	11th to 20th	Night	17% 6% 32% 29% 15% 1	570
	21st to end	Night	21% 11% 31% 26% 11% 1	642
October	1st to 10th	Night	24% 11% 31% 26% 8%	760
	11th to 20th	Night	24% 13% 31% 26% 6% 1	760
	21st to end	Night	26% 10% 36% 22% 5% 1	873
November	1st to 10th	Night	23% 9% 33% 27% 6% 1	950
	11th to 20th	Night	24% 12% 32% 26% 5% 1	950
	21st to end	Night	22% 15% 37% 21% 4	950
December	1st to 10th	Night	17% 11% 36% 27% 8% 1	950
	11th to 20th	Night	19% 11% 36% 24% 8% 1	950
	21st to end	Night	24% 10% 31% 26% 9% 2	1045

Page generated at 2024-11-03 01:11:27. Version ac07

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