The Salmonfly hatch lasts about two weeks, moves upriver a few miles a day, and turns on when the water hits a narrow temperature band. Miss the window and you wait a year. A hatch chart will tell you it usually happens in June; it will not tell you that the water crossed 52 degrees this morning and the bugs are coming off right now. That gap — between a calendar and what the river is actually doing today — is exactly what a hatch alert closes.
This guide walks through setting a hatch alert in FlyGuysNLies — the app appears as FlyGuys on your home screen — from favoriting a river to picking the bug and choosing when the app should ping you. We use the Colorado River at Pumphouse here because it has a water-temperature gage and a marquee Salmonfly hatch; any river with a temperature gage works the same way. By the end you will have an alert that watches the water temperature for you and sends a notification the moment your hatch is about to start.
What hatch alerts do, and why they matter
A hatch chart is a forecast for the season. A hatch alert is a tap on the shoulder for the day. Instead of you checking water temps every morning in June, FlyGuysNLies watches the river for you and notifies you when the temperature crosses into the emergence window for the specific hatch you care about — Salmonfly, Green Drake, Pale Morning Dun, Blue-Winged Olive, and the other insects on that river’s chart.
The trigger is water temperature, not a date. Each hatch has an emergence range built from the river’s hatch data, and the alert fires when the live water temperature enters — or, if you choose, approaches — that range. It is a one-shot-per-event signal: the alert fires once when conditions turn on, then goes quiet so your phone is not buzzing every hour, and it resets after the hatch window passes. That is the difference between a notification you trust and one you mute.
One requirement to know up front: because the trigger is live water temperature, hatch alerts only work on rivers that have a water-temperature gage. On a river without one, the Hatch option is greyed out in the alert builder with the note “This river doesn’t have a temperature sensor.” That reading comes from a live streamgage fitted with a temperature sensor. Many tailwaters and freestones across the West report it; the Colorado River at Pumphouse, used in this guide, is one of them. If your home water shows the Hatch option disabled, that gage simply doesn’t report temperature — pick a river that does, or set a flow or verdict alert instead.
It is also a feature you will not find anywhere else. Tying a push notification to live water temperature and a river-specific emergence window takes the temperature integration and the hatch taxonomy to already be in place — which is why hatch alerts are the kind of thing FlyGuysNLies can do and a map with pins cannot.
How to set a hatch alert, step by step
The alert builder lives one tap behind each river’s screen — the bell icon in the header — so the walkthrough starts by opening a river and ends with a finished alert in your list. Two things make a river ready: it must have a water-temperature gage (so the alert has something to watch), and on the free tier you set alerts on rivers you have favorited. Step 1 covers favoriting; the temperature gage is a property of the river itself.
Start on the Rivers tab, search for the river you want to watch, and tap it to open River Detail. For this guide, open the Colorado River at Pumphouse. Tap the favorite star so the river is saved to your favorites — on the free tier this is what lets you set an alert on it. (Premium members can skip this and alert any river.)
Expected result: The Colorado River at Pumphouse is in your favorites (the bookmark in the header is filled) and its live conditions are on screen — including the water temperature reading that powers the hatch alert. The bell icon in the header is outlined, meaning no alerts are set yet.
Tap the bell icon in the river’s header — outlined when you have no alerts yet — to open the Create Alert screen. Choose your activity if prompted (Wading or Floating), then in the Alert Type row tap Hatch. The screen fills in with the hatch controls: an info line spelling out the trigger — for example, “Get notified when water temp reaches 50°F – 56°F — Salmonfly emergence conditions” — and a Species picker. Under Species, tap the bug you want to watch. The chips list the hatches the app has data for on that river — on the Colorado at Pumphouse that includes Salmonfly, PMD, Caddis, Golden Stone, and more. (If Hatch is greyed out, the river has no temperature gage — see the note above; back out and choose a river that reports water temperature.)
Expected result: Hatch is selected, your species is highlighted, and the info line shows that insect’s emergence temperature range.
Use the Trigger Mode control to set the timing. At Range fires the moment the water temperature reaches the emergence window — the hatch is on now. Early Warning fires a few degrees before the window, giving you a head start to plan the drive; when you pick it, a Warning Offset row appears so you can choose how early — 2°, 3°, or 5° below the range. An emergence card spells out the math, for example “Salmonfly emergence: 50°F – 56°F water temperature / Active on this river: Jun 1 – Jun 25 / Warning at 47°F (3° below emergence).”
Expected result: You have chosen At Range or Early Warning, and the emergence card shows the exact temperature the alert will trip at.
Scroll down to set your delivery channels if you like — Push is on by default and Email is available — then tap Create Alert. A confirmation appears — Alert Created — naming exactly what the app will watch for: “You’ll be notified when water temp indicates Salmonfly emergence (8h cooldown).” Tap OK.
Expected result: The alert is saved and the confirmation names your hatch and the 8-hour cooldown.
You land on the river’s alert list — titled with the river name — where your new alert is listed by hatch and mode, such as “Salmonfly emergence (Early warning)”, with the gage shown as Online. Toggle it off and on, edit it, or delete it from here, and tap the ＋ to add more. Every alert you set across all your rivers also lives together under My Alerts.
Expected result: The hatch alert is active on the river, ready to notify you when the water hits the window.
Turning alerts into a season plan
One alert is useful; a small set is a strategy. Pick two or three home waters that have temperature gages, favorite them, and set the hatch you most want to catch on each — a Salmonfly Early Warning on a freestone you would drive for, an At Range blue-winged olive on a tailwater you can reach in twenty minutes. The same alerts bell sits on every river card in your Favorites, so once your home waters are saved you can set or check each one’s hatch alert right from that list — no need to open every river first. The app then watches all of them and tells you which river turns on first, so your limited days off land on real emergences instead of guesses. When an alert fires, jump to that river’s page — for example the Colorado River at Pumphouse — to check flows and access, and open the full hatch chart and fly choices for the bug that is coming off so your fly box is ready before you leave.
If you are new to reading emergence windows, the species guides are the place to start: the pale morning dun and blue-winged olive pages explain the water temperatures and times of day each hatch favors, which is the same logic the alert is using under the hood. And because water temperature tracks the season’s warming, it is worth a glance at the National Weather Service forecast for the days around a predicted emergence so you can pair the hatch with fishable weather.
Frequently asked questions
What is a hatch alert?
A hatch alert is a notification that fires when a river’s live water temperature indicates a specific hatch is starting. You choose the insect — Salmonfly, Green Drake, Pale Morning Dun, Blue-Winged Olive, and others on the river’s chart — and FlyGuysNLies watches the water temperature and pings you when it crosses into that hatch’s emergence window. It is condition-triggered, not a calendar reminder.
Are hatch alerts free in FlyGuysNLies?
Yes. On the free tier you can set a hatch alert on any river you have favorited. Premium removes the favorites requirement, so you can set alerts on any river and keep as many as you want at once.
What is the difference between At Range and Early Warning?
At Range fires when the water temperature reaches the hatch’s emergence window — the hatch is on right then. Early Warning fires a few degrees before the window (you choose 2, 3, or 5 degrees), giving you lead time to plan the trip before the bugs are up.
Why is the Hatch alert option greyed out on my river?
Because hatch alerts are triggered by live water temperature, they only work on rivers with a water-temperature gage. If the river’s gage doesn’t report temperature, the Hatch option is disabled and the app shows “This river doesn’t have a temperature sensor.” Choose a nearby river that reports water temperature, or set a flow or verdict alert instead.
Which hatches can I set alerts for?
Whichever insects have data on that river’s hatch chart. A freestone like the Colorado at Pumphouse surfaces big-ticket hatches such as Salmonfly alongside Pale Morning Dun and Caddis; tailwaters lean toward mayflies and midges like Blue-Winged Olive and Pale Morning Dun.
Never miss the hatch again
Stop checking water temps by hand every morning in June. Download FlyGuysNLies, favorite your home water, and set a hatch alert so the FlyGuysNLies app pings you the moment the hatch turns on — water temperature, emergence window, and your bug, watched for you.
Tight lines!
— The FlyGuysNLies Team
